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Stevens, Kim. "Multiplicity of viral infection in brown algae." Thesis, University of Plymouth, 2014. http://hdl.handle.net/10026.1/3156.
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Brown algae are important primary producers and habitat formers in coastal environments and are believed to have evolved multicellularity independently of the other eukaryotes. The phaeoviruses that infect them form a stable lysogenic relationship with their host via genome integration, but have only been extensively studied in two genera: Ectocarpus and Feldmannia. In this study I aim to improve our understanding of the genetic diversity, host range and distribution of phaeoviruses. Sequencing and phylogenetic analysis of amplified fragments of three core phaeoviral genes (encoding major capsid protein (MCP), DNA polymerase and superfamily III helicase) of phaeovirus infected algae confirmed the suspected phaeoviral identity of viruses infecting E. fasciculatus, F. simplex, Pilayella littoralis, Myriotrichia clavaeformis and Hincksia hincksiae. Furthermore, this approach revealed multiple virus sequence variants within individual strains, and moreover that the variants formed two distinct subgroups. Subgroup A was highly conserved and observed in multiple algal genera, whereas subgroup B was much more diverse, but only found in Feldmannia species. Transcriptome sequencing of an actively infected F. irregularis strain revealed polymorphisms within key viral genes, suggesting that multiple variants were indeed active within this strain. High resolution melt curve (HRM) technology was used to develop a high throughput screening method for detecting phaeoviral MCP as a proxy for detection of phaeoviruses. This technique was also able to assign 88% of those detected to one of the subgroups, based on their differing melting temperature distributions. This was then applied to 1034 Ectocarpus isolates collected from around Europe and South America, and in accordance with previous studies of phaeoviral infection, 43-79% of strains contain virus sequence (depending on species). 17% of the isolates tested even contained sequence from both subgroups. 82 Laminariales strains, close relatives of the Ectocarpales, were also screened because they comprise commercially important kelp species but are not known to be infected by viruses. 10-17% of these tested positive for phaeoviral MCP, which when sequenced formed a separate group within the phaeoviruses. This finding could have a major impact on the kelp farming industry if the viruses are found to affect reproduction as happens in the Ectocarpales. The discovery of two subgroups is contrary to current beliefs that the phaeoviruses are a single monophyletic group, and that each species of alga has its own phaeovirus, casting doubt on the usefulness of the current convention of naming each phaeovirus after its host. It appears that the subgroup B viruses have begun to evolve away from the stable, K-selected subgroup A viruses towards a more r- type strategy with higher mutation and diversification. This study has identified potential mechanisms that may influence this shift, including mutations in a region of the DNA polymerase known to negatively affect DNA replication fidelity, combined with an active integrase and lack of a proofreading exonuclease, along with the observed infection of individuals with both phaeovirusal subgroups. The resulting mutations and recombinations could lead to the diversity observed here, and may provide a suitable model for the study of other emergent virus infections.
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Murúa, Pedro. "Molecular and cell biology of novel brown algal pathosystems." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238693.
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Algae are increasingly being used in human affairs. Alongside with higher volumes, threats for seaweed natural reservoirs and seaweed farming are starting to appear. Epidemics seems a key complication, similar to agriculture and animal aquaculture. However, phycopathologies are much more under documented, and future diseases are currently difficult to foresee. Thus, efforts should be stressed on biodiversity of algal pathogens and algal defense strategies against diseases. This thesis is divided in two parts: the first section comprises Chapters Two and Three, which describe novel algal pathosystems from cell biology and molecular phylogeny perspectives. Chapter Two characterizes the obligate parasite Maullinia braseltonii sp. nov., a phytomyxid infecting Durvillaea (bull kelp) in the Southern hemisphere. Chapter Three reports new records, cell plasticity and epidemiology of the endophyte Laminariocolax aecidioides infecting Lessonia berteroana (huiro negro) in northern Chile. The two hosts aforementioned have commercial importance, and remarkable roles in coastal ecology in temperate marine habitats in the Southern hemisphere. Chapters Four, Five and Six correspond to a second section and describe cellular processes in novel brown algal pathosystems, related with infection and immunity responses. In Chapter Four, using the Macrocystis/Anisolpidium as a model, microscopy evidence indicate that autophagy is a key cellular process used either to help starving pathogen syncytia to survive (controlled) or to kill themselves (abortive), probably induced by the host. Likewise, host autophagy was also widely observed and may be involved in the neutralization of early-stage oomycetes or nutrient recycling to mount defences. Chapter Five shows the results on a screening of ca. 40 strains from different brown algal orders, to phenotype cellular defense markers against two phylogenetic distant pathogens (Anisolpidium ectocarpii and Maullinia ectocarpii). Overall, responses such as cell wall re-arrangements, programmed cell death, autophagy and ROS accumulation were confirmed to be at least partially conserved across different Phaeophycean lineages. Chapter 6 reports a boost on the phlorotannin metabolism in the model brown alga Ectocarpus (e.g. physode formation and polyketide synthase gene expression) after pathogen challenging, suggesting a similar protective role of this molecule as against grazers and deleterious light regimes. Phlorotannins role however needs to be elucidated.
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Hotchkiss, Sarah L. "Life history strategies of three species of Cystophora (Phaeophyta, Fucales) from a shallow subtidal community in South Australia /." Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phh832.pdf.
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Torode, Thomas Adrian. "Molecular probes for the cell walls of brown algae." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/12218/.
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The brown algae are an abundant source of renewable biomass that do not require arable land or fresh water for cultivation. Cell walls of the brown algae contain a range of unique polysaccharides with useful bioactivities; namely the sulphated fucans and alginate. The generation and characterisation of ten new monoclonal antibodies (MAbs) towards components of brown algal cell walls are described. Four MAbs, BAM1 to BAM4, recognise un-sulphated (BAM1) and sulphated (BAM2/3/4) structures of the sulphated fucans. Six MAbs, GIN1 to GIN6, recognise different structures of the alginate, ranging from high mannuronate content (GIN4) to high guluronate content (GIN6). The combination of these new MAbs, pre-existing knowledge of the brown algal cell walls and, techniques commonly used in land plant cell walls have allowed an extensive study of cell wall architecture in the brown algae. The extraction and fractionation of the cell wall has revealed that the sulphated fucans and alginate are distributed throughout the cell wall architecture and that there are differences in cell wall architecture between orders of the brown algae. Investigation into the abundance of sulphated fucans in the intertidal zone showed trends for increased sulphated fucan content higher up the intertidal zone (as determined by BAM3 and BAM4), but also revealed a ubiquitously distributed set of sulphated fucans (as determined by BAM1 and BAM2). Within tissues of the algae; sulphate fucans and alginate are spatially distributed both in terms of abundance and incorporation into the cell wall architecture – and these traits are shared between species of Fucus. Use of indirect immunohistochemistry allowed dissection of the sulphated fucan and alginate distribution in muro (in wall); revealing cell type specificity and patterning of the polysaccharides.
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Jorge, Ricardo Ferreira. "Isolation and structural characterization of fucoidans from the brown algae Fucus vesiculosus." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15669.
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Mestrado em Biotecnologia - Biotecnologia Molecularagricultural, pharmaceutical, cosmetic or bioenergy applications. They contain bioactive compounds, namely, polysaccharides Fucoidan. These polysaccharides are mainly constituted by fucose residues and sulfate esters, and have been reported to possess a broad variety of bioactivities, such as anticoagulant, anti-thrombotic, anti-inflammatory, anti-tumor, antiviral and antioxidant. In this work, the fucoidans from brown seaweed Fucus vesiculosus from “Ria de Aveiro” were isolated and characterized in order to add value to this natural resource of the region. The polysaccharides from the algae were extracted with hot water and fractioned by ethanol precipitation and calcium chloride salts. They were further purified by using anion-exchange chromatography, allowing to separate the neutral polysaccharides (laminaranas) from those negatively charged (sulfated fucoidans and alginate). The purified polysaccharides showed high content of fucose (41 mol%) and sulfates (50 mol%), having also galactose residues (6 mol%), which confirm the presence of only sulfated fucoidans. Glycosidic linkages analysis show the presence of high amounts of terminal fucose (25%) and (1→3,4)-Fuc (26%), allowing to infer that the fucoidans were highly branched. These fucoidans are composed also by (1→2)-Fuc (14%) and (1→3)-Fuc linkages (10-16%). In this work it was also tested an alternative extraction technology, the microwave hydrodiffusion and gravity system, where it was possible to extract sugars, although in low yields. However, this methodology allowed to extract polysaccharides, constituted mainly by fucose and uronic acids, as well as mannitol, without the need to add any solvent, obtaining at the end the dry alga. The current work allowed to characterize the structure of the fucoidans isolated from “Ria de Aveiro” F. vesiculosus. The presence of high content of sulfate residues and the high branch degree of the purified fucoidans allow to infer that these polysaccharides could have potential to be studied for biomedical applications, according to their biological activities.
As algas castanhas fazem parte de um grupo de organismos cuja utilização tem vindo a crescer nas áreas da alimentação, agricultura, farmacêutica, cosmética e bioenergia. Estas algas são constituídas por diversos compostos com atividades biológicas destacando-se as fucoidanas. Estas são polissacarídeos compostos maioritariamente por fucose e ésteres de sulfato, apresentando várias atividades biológicas, tais como anticoagulante, anti trombótica, anti-inflamatória, anti-tumoral, antivírica e antioxidante. Neste trabalho foram isoladas e caracterizadas as fucoidanas da alga castanha, Fucus vesiculosus, da Ria de Aveiro de forma a potenciar este recurso natural da região. Os polissacarídeos constituintes da alga foram extraídos com água quente e fracionados por precipitação em etanol e sais de cloreto de cálcio. Os polissacarídeos foram purificados utilizando uma cromatografia de troca aniónica, permitindo separar os polímeros neutros (laminaranas) dos carregados negativamente (fucoidanas sulfatadas e alginatos). Os polissacarídeos purificados eram constituídos por fucose (41 mol%) e sulfatos (50 mol%), contendo também galactose (6% mol), comprovando a presença de apenas fucoidanas sulfatadas. A análise das ligações glicosídicas, mostrou a presença de fucose terminal (25%) e (1→3,4)-Fuc (26%), demonstrando que as fucoidanas eram muito ramificadas. Outras ligações presentes são (1→2-)-Fuc (15%) e (1→3)-Fuc. Neste trabalho foi também testada uma tecnologia de extração alternativa, o sistema de micro-ondas de hidro-difusão e gravidade, onde foi possível extrair alguns açúcares, embora com rendimentos reduzidos. Esta metodologia permitiu extrair os polissacarídeos, constituídos por fucose e ácidos urónicos, e também manitol sem necessidade de adicionar qualquer solvente e permitindo obter a alga seca no final da extração. Este trabalho permitiu caracterizar estruturalmente as fucoidanas isoladas do F. vesiculosus da Ria de Aveiro. A elevada quantidade de ésteres de sulfato e o elevado grau de ramificação sugere que estes polissacarídeos têm potencial para serem estudados em relação às suas atividades biológicas para serem usados em aplicações biomédicas.
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Pelletreau, Karen Nicole. "The application of molecular tools towards the study of brown algal chemical ecology and the production of phlorotannins." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 230 p, 2008. http://proquest.umi.com/pqdweb?did=1601234901&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Bown, Polly Louise. "Endophytic green and brown algae associated with a population of Chondrus crispus Stackhouse." Thesis, University of Bristol, 2001. http://hdl.handle.net/1983/ec8625fb-5396-4366-9a6c-93dadc2ff699.
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Ruchonnet, Diane Astrid. "The chemical ecology and antibacterial activity of the brown alga Halidrys siliquosa and other Scottish seaweeds." Thesis, University of Aberdeen, 2007. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=186834.
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In regard to the more and more restrictive legislations on the use of organotins in antifouling coatings the need for the development of 'environmentally friendly' antifouling formulations becomes urgent. This study was initiated by the screening of the antifouling activity of Scottish algae against marine fouling bacteria aI;ld was followed by an examination ofthe chemical ecology ofthe brown alga Halidrys siliquosa. Of eleven algal species tested, eight exhibited good antifouling activity, confirming marine algae as a potential source for the development ofnovel antifouling formulations. H. siliquosa crude extracts tested at concentrations equivalent to whole algal tissue inhibited bacterial growth, with bacteria isolated from the surface orH. siliquosa being less sensitive to the extracts compared to bacteria isolated from stones and open seawater. This suggested for the first time that bacteria associated with the surface of the seaweed had evolved some kind of resistance to the plant antimicrobial activity. Characterisation of the active components using NMR spectroscopy showed the activity to be largely associated with the presence of polyunsaturated fatty acids (PUFAs). Examination of purified fractions using GCIMS allowed identification and quantification of PUFAs 18:2, 18:4, 20:4 and 20:5. A separate study, determining minimum inhibitory concentrations of 18:2 and 20:4 against marine fouling bacteria indicated that both acids were present in sufficient concentrations in the plant to inhibit bacterial growth. The presence of PUPAs on the surface of the seaweed could not be demonstrated using a surface dip technique; however, this technique was originally developed for the extraction of non-polar metabolites only. This study suggests that PUFAs produced by H. siliquosa are potentially able to regulate biofouling by means of disrupting the early stage of biofilm development, i.e. bacterial colonisation. However, to confirm this hypothesis, the presence of PUFAs on the surface of the plant' still needs to be demonstrated.
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Linardic, Marina. "The role of brown algal cell walls in morphogenesis and development." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274933.
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Morphogenesis in walled organisms represents a highly controlled process by which the variability of shapes arises through changes in the structure and mechanics of the cell wall. Despite taking different evolutionary paths, land plants and some brown algae exhibit great developmental and morphological similarities. In two brown algal model systems: the Sargassum muticum apex and the Fucus serratus embryo, I have used a combination of imaging techniques, growth analyses, surgical and pharmacological treatments, as well as molecular, biochemical and mechanical approaches to characterise the growth patterns and the cell wall contribution to shape change. To understand how the adult algal body is formed, I examined the branching strategy (phyllotaxis) in S. muticum. My results suggest that in S. muticum the spiral phyllotactic pattern and the apical cell division pattern are not linked. The phytohormone auxin and the biochemical changes of the cell wall do not seem to be correlated with the bud outgrowth, contrary to observations in plants. In summary, these results suggest Sargassum convergently developed a distinct growth mechanism with similar shape outcome as observed in plants. This dissertation is one of the first attempts to explore cell wall mechanics in brown algal development and its correlation with underlying cell wall biochemistry utilising the Fucus embryo as a known system. The results suggest a correlation between the wall mechanics and alginate biochemistry with the growing and non-growing regions of the embryo. In addition, altering cell wall deposition or composition has a strong effect on embryo rhizoid elongation and is, in certain cases, accompanied by significant increase in cell wall stiffness and reduction of alginate epitopes. Furthermore, preliminary results exploring transcriptomic changes during development indicate differential expression of particular alginate biosynthesis enzymes (mannuronan C5 epimerases) during development, suggesting alginate conformational modifications might be stage specific. These results contribute to the current knowledge addressing the importance of cell walls in brown algal development using novel tools and approaches. Understanding developmental processes in brown algae will provide a better insight how similar morphogenetic traits are established using different body-building mechanisms.
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Creis, Emeline. "Etude de la voie de biosynthèse des phlorotannins chez les algues brunes, de la caractérisation biochimique d'enzymes recombinantes à l'étude des réponses écophysiologiques." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066095/document.
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Les phlorotannins, polymères du phloroglucinol, sont des composés phénoliques (CP) uniquement retrouvés chez les algues brunes (Phéophycées). Ces métabolites présentant des activités anti-oxydantes, interviendraient dans la formation de la paroi, mais à ce jour leur voie de biosynthèse reste non élucidée. L'annotation du génome de l'algue brune Ectocarpus, a permis d'identifier des gènes homologues codant pour des enzymes de la biosynthèse des CP chez les plantes terrestres. Une polyketide synthase de type III (PKSIII), a été caractérisée: elle synthétise le phloroglucinol. La recherche d'autres cibles a été poursuivie sur des gènes codant pour des chalcone-isomérases-like (CHIL), ainsi que pour des phénol-sulfotransférases homologues d'enzymes de sulfatation des flavonoïdes. Les CHIL se sont révélées être des fatty acid binding protein (FAP) impliquées dans le métabolisme des acides gras. L'intérêt pour cette nouvelle famille a justifié leur caractérisation biochimique puis fonctionnelle par complémentation de mutants FAP d'Arabidopsis thaliana. L'élucidation progressive des voies de biosynthèse des phlorotannins a servi de base pour étudier les mécanismes de régulation de ce métabolisme chez les Phaeophycées. En combinant des approches intégrées d'expression de gènes cibles, de dosages et de profilages de phlorotannins solubles, nous avons pu montrer que ces composés assurent une protection constitutive chez Fucus vesiculosus en réponse aux UV-B, et que leur métabolisme serait induit très précocement au cours de l'herbivorie. Le développement d'outils moléculaires spécifiques de ces voies métaboliques, ouvre de nouvelles perspectives en écophysiologie et en écologiePhlorotannins are polymers of phloroglucinol that are specific phenolic compounds of brown algae (Phaeophyceae). These metabolites present antioxidant activities and are potentially involved in the formation of cell-walls but their biosynthetic pathway is currently uncharacterized. The genome annotation of the brown algae Ectocarpus provided some information about conserved genes which are implicated in the synthesis of phenolics in terrestrial plants. One polyketide synthase of type III (PKSIII) has been successfully characterized: it produces phloroglucinol. The search for other targets has been pursued in brown algae focusing mainly on chalcone isomerase-like (CHI-like) genes, as well as on phenol-sulfotransferases, which are implicated in the sulfation of flavonoids. The characterization of CHIL has revealed their implication in fatty acid binding (FAP). However, the level of interest for this new family has led to their biochemical characterization and to functional studies by complementation of gene in the Arabidopsis thaliana FAP mutant. The progressive elucidation of the phlorotannin biosynthesis pathway has been used in order to discover mechanisms which regulate this metabolism in brown algae. By combining integrated approaches of gene expression profiling with the quantification and profiling of soluble phlorotannins, we have shown that these metabolites ensure the constitutive protection in Fucus vesiculosus against UV-B radiation and could also be induced as a very early response to grazing. The development of specific molecular tools for this metabolic pathway opens some news perspectives in ecophysiological and ecological studies
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Mubaiwa, Byron Tawanda. "The quantification of fucoxanthin from selected South African marine brown algae (Phaeophyta) using HPLC-UV/Vis." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1017879.
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Marine brown algae (seaweeds) are a rich source of fucoxanthin, a xanthophyll carotenoid that is naturally, an accessory pigment in the process of photosynthesis of sea vegetation such as Sargassum incisifolium. Fucoxanthin has been exploited by nutraceutical companies for its anti-obesity effects that has resulted in an increase of seaweed slimming preparations such as FucoThin™. The field is getting widespread consumer attention as interest in fucoxanthin has also transcended to its widespread biological potential which include cytotoxicity, anti-diabetic, anti-oxidant, anti-inflammatory and anti-plasmodium effects. We therefore wanted to identify a reliable source(s) of fucoxanthin from diverse samples of South African marine brown algae in order to explore our medicinal chemistry interests around the cytotoxicity and anti-malarial potential of fucoxanthin. A known source, Sargassum incisifolium, was used to isolate (maceration in CH₂Cl₂/MeOH at 35 °C followed by a hexane/EtOAc step gradient silica column of the crude extract and reversed phase semi-prep HPLC) and characterize (1D and 2D NMR) fucoxanthin (reference standard) in order to develop an analytical method for its determination in selected diverse brown algae commonly found in South Africa. The HPLC [Column: Phenomenex® Synergi™ (250 x 3.0 mm i.d); Mobile phase: ACN/H2O (95:5)] method developed for this analysis was validated according the guidelines set by the International Conference on Harmonization (ICH). Fifteen species were then assessed for fucoxanthin content (μg/g of dried weight) using the developed method. Stability studies on fucoxanthin were also carried out to assess photo- and pH degradation of fucoxanthin. Zonaria subarticulata (KOS130226-18) from Kenton-On-Sea beach and Sargassum incisifolium (PA130427-1) from Port Alfred beach were found to be the highest producers of fucoxanthin with 0.50 mg/g and 0.45 mg/g dried weight respectively. Fucoxanthin was found to be both photo-labile and sensitive to both acidic and basic pH environments. However, the pigment was more photostable in pure as opposed to extract form and also showed to be more stable at pH 10.0. Our findings show that Z. subarticulata and S. incisifolium could be reliable sources of fucoxanthin and can be considered as the algae to use in optimized extraction procedures in further studies. Also, when working with fucoxanthin, it is important to protect it from light. Any consideration of taking fucoxanthin preparation orally (as a nutraceutical) should consider protecting the active from the harsh conditions of the gastrointestinal tract. Any upscale production of fucoxanthin from seaweed should consider variations such as geographical, seasonal, lifecycle stage, etc. of identified algae as these may be important factors in obtaining effective concentrations of fucoxanthin.
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Lawson, Jessica Clair. "Analysis of the anti-cancer activity of novel indigenous algal compounds in breast cancer: towards the development of a model for screening anti-cancer stem cell activity." Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1003984.
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Breast cancer, the most common malignancy diagnosed in women, is one of the leading causes of death in women worldwide. In South Africa only 32% of women diagnosed with advanced breast cancer survive more than five years. The search for new chemotherapeutic agents capable of effectively treating breast cancer is therefore essential. Recent evidence supporting the cancer stem cell theory of cancer development for breast cancer challenges the current theories of cancer development and hence treatment. Cancer stem cells are a small subpopulation of tumour cells that possess properties of both cancer cells and stem cells and are believed to be the tumour-initiating population of many cancers. Cancer stem cells are inherently resistant to many chemotherapeutic agents and in this way have been associated with repopulation of tumours after chemotherapy. This phenomenon is proposed as a possible mechanism for cancer relapse after treatment. Cancer stem cells have also been implicated in metastasis, the major cause of mortality in cancer patients. Therefore, any treatment that is capable of targeting and removing breast cancer stem cells may have the theoretical potential to effectively treat breast cancer. However, there are currently no such treatments available for clinical use. We were provided access to a library of novel indigenous small molecules isolated from red and brown algae found off the Eastern Cape of South Africa. The aim of this project was to analyse the anti-cancer and anti-cancer stem cell properties of the compounds in this library and to identify „hit‟ compounds which could form the basis for future development into new anti-cancer drugs. Ten novel compounds of algal origin were tested for cytotoxicity, by determining their ability to inhibit the growth of MCF12A breast epithelial cells and MCF7 breast cancer cells using the colorimetric MTT [(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] cell proliferation assay. All but one of the compounds tested exhibited cytotoxicity towards the MCF7 cancer cell line, with IC50 values (the concentration of the compound that leads to a 50% inhibition in cell growth) of between 3 μM and 90 μM. The chemotherapeutic drug paclitaxel was used as a positive control. Four of the compounds (RUMB-001, RUMB-002, RUMB-007 and RUMB-010/saragaquinoic acid) were significantly more toxic to the MCF7 cancer cell line, than the „normal‟ MCF12A breast cells and were selected as priority compounds for further analyses. In addition, two other compounds were selected as priority compounds, one highly cytotoxic towards both MCF12A and MCF7 cell lines (RUMB-015) and one which was non toxic to either cell line (RUMB-017/018). Preliminary studies into the mechanism of cytotoxicity using Western blot analysis for poly (ADP-ribose) polymerase (PARP) cleavage and Hoechst 33342 immunostaining in MCF-7 cells were largely unsuccessful. The Hoechst 33342 immunostaining assay did provide tentative evidence that selected priority compounds were capable of inducing apoptosis, although these assays will need to be repeated using a less subjective assay to confirm the results. The priority compounds were subsequently investigated for their cytotoxic effect on the cancer stem cell-enriched side population in MCF7 cells. The ability of the priority compounds to selectively target the cancer stem cell containing side population was assessed using two complementary flow cytometry-based techniques – namely the Hoechst 33342-exclusion assay, and fluorescent immunostaining for the expression of the putative cancer stem cell marker, ABCG2+. The ABCG2+ staining assay was a novel technique developed during the course of this study. It remains to be fully validated, but it may provide a new and reliable way to identify and analyse cancer stem cell containing side population cells. The MCF7 cells were treated with the compounds and the proportion of putative cancer stem cells compared with the size of the population in untreated cells was assessed. Three compounds (RUMB-010, RUMB-015 and RUMB-017/018) capable of reducing the proportion of side population cells within the MCF7 cell line were identified. Taking these data together, we identified two potential „hit‟ compounds which should be prioritised for future research. These are compounds RUMB-010/sargaquinoic acid and RUMB-017/018. RUMB-010 is of interest as it was shown to target the putative cancer stem cell population, in addition to the bulk MCF7 tumour line, but was relatively less toxic to the „normal‟ MCF12A cell line. RUMB-017/018 is of interest due to the ability to selectively target the cancer stem cell enriched side population, while having little effect on the normal (MCF12A) or bulk tumour (MCF7) cell lines tested. These compounds will be important as „hit‟ compounds for drug development and as tool compounds to study cancer and cancer stem cell biology.
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Maina, Mwangi Henry. "Structural investigation of the natural products composition of selected South African seaweeds." University of the Western Cape, 2014. http://hdl.handle.net/11394/4339.
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Philosophiae Doctor - PhDRecently, a great deal of interest has developed towards the isolation of bioactive compounds from marine sources due to their numerous health benefits. Furthermore, marine algae are valuable sources of structurally diverse metabolites with scientifically proven therapeutic claims. The cell walls are rich in sulfated polysaccharides such as fucoidans in brown algae, carrageenans in red algae and ulvans in green algae. These sulfated polysaccharides exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, anticancer and immunomodulating activities. They have great potential for further development as products in cosmeceutical, pharmaceutical and nutraceutical areas. Although the mechanism of action is still not clear, their biological activities could be mainly attributed to their major secondary metabolites namely; phlorotannins, terpenoids and fucoidans. There was use of comprehensive chromatographic separations and a full analysis of isolates using one or other of the spectroscopic techniques. Antioxidant and cytotoxicity tests were perfomed in details for Ecklonia maxima. Furthermore, structural and electronic features of the phlorotannins were compared in an attempt to provide an explanation for the differences in their radical scavenging properties. In this regard, two main radical scavenging mechanisms, hydrogen atom transfer (HAT) and electron transfer (ET), were assessed in order to determine the preferred mode of radical scavenging. Fully relaxed geometry optimizations of the neutral and the radical species were performed utilizing DFT/B3LYP and DFT/UB3LYP methods respectively. In further studies, the structural and functional properties of sulfated polysaccharides from the three brown and one red seaweeds were investigated. This was through detailed analysis of chemical composition of crude and purified polysaccharides using PMP - derivatization of hydrolysed sugars, anion exchange, molecular weight determination, ion chromatography , FT-IR, NMR to methylation analysis. The work reports isolation and characterization of compounds from four algae: Ecklonia maxima, phlorotannin derivatives, namely phloroglucinol (22), eckol (23), 7-phloroeckol (24), 2-phloroeckol (25) and a sterol, 24-ethylidine cholesterol (26); Splachinidium rugosum, 24-ethylidine cholesterol ( 26), 1, 3-Dicapryloyl-2-oleoylglycerol (27), E-3,7,11,15-tetramethylhexa dec-2-en-1-ol (phytol) (2 8); Macrocystis angustifolia, 24-ethylidine cholesterol (26); a red seaweed Aeodes orbitosa, and E -3, 7, 11, 15-tetramethylhexad ec-2-en-1-ol (28) and 17-(5-Ethyl-6-methylheptan-2-yl)-10,13-dimethyl-2,3,4,7, 8,9,11,12,14,15,16,17-dodecahydro-1 H-cyclopenta[a]phenanthren-3-ol (β-sitosterol) (29). Experimental findings and theoretical predictions of phlorotannins indicated that the radical scavenging activities followed the order 22< 23 < 25 < 24. Theoretical studies further indicated the ET mechanism is more significant than the HAT mechanism due to the high BDE values. Their polysaccharide structures were tentatively shown to have a backbone of (1-3) and (1-4) linkages with sulfate groups at O-2 and O-2, 3 positions. The only red algae studied contained, 2-O-methyl-D-galactose with (1-3) and (1-4)-glycosidic linkages possessing sulfate groups at positions 2 and 6.
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Manuel, Theodore Llewellyn. "The biology and ecology of Bifurcaria brassiceaformis (Kütz) Barton (Phaeophyta, Fucales)." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/22478.
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Summary in English.Bibliography: pages 146-169.
The biology, population dynamics, and the environmental tolerances (temperature and light) in laboratory culture, of the endemic intertidal South African fucoid Bifurcaria brassicaeformis (Kütz) Barton have been investigated. A general description is included of the morphology and anatomy, and comparisons made with that of other species in the genus. Studies on plants collected from contrasting habitats on the lowshore and from mid-shore pools revealed that while cortical thickness of vegetative uprights were similar for both habitats, medullary diameters were generally higher, corresponding to generally thicker uprights in the low-shore. Observations on the method of zygote attachment revealed that attachment of the species resembles that of the European Bifurcaria and Halidrys siliguosa which both also display delayed rhizoidal development and initially attach by means of a mucilage secretion of the zygote wall. Observations on receptacle anatomy revealed that size of conceptacles increase from the apex to the base of a receptacle.
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Tourneroche, Anne. "Bacterial-fungal interactions within the endomicrobiota of brown algae : implication of quorum sensing in the metabolic crosstalk." Thesis, Paris, Muséum national d'histoire naturelle, 2018. http://www.theses.fr/2018MNHN0013.
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Les macroalgues hébergent de nombreux micro-organismes, collectivement désignés sous le terme de microbiote algal, qui ont un rôle essentiel dans le développement et l’état de santé de leur hôte. Dans ce travail, nous avons exploré le microbiote fongique et bactérien d’algues brunes, ainsi que l’impact des interactions bactérie-champignon sur la médiation chimique et, en particulier, sur le quorum sensing bactérien. Par des approches de metabarcoding ciblant l’ADNr 16S et l’ITS2, nous avons montré que les communautés fongiques et bactériennes associées à la macroalgue brune Saccharina latissima étaient très riches, principalement composées de quelques OTUs dominants, et d’une grande abondance d’OTUs « rares ». De manière intéressante, les communautés fongiques comme bactériennes différaient de celles de l’eau de mer environnante et paraissaient spécifiques des tissus algaux. Cependant, de grandes variations intra et interindividuelles de composition ont été observées au sein des échantillons de tissus d’algue. Ainsi, ce qui définit la spécificité des communautés microbiennes reste à préciser. En parallèle, nous avons exploré la médiation chimique au sein de l’endomicrobiote de quatre algues brunes : Saccharina latissima, Laminaria digitata, Pelvetia canaliculata et Ascophylum nodosum, et révélé que de nombreux endophytes fongiques et bactériens isolés synthétisaient des métabolites interférant avec les systèmes de quorum sensing bactériens, en les induisant ou les inhibant. De plus, les bioessais basés sur les biosenseurs, couplés à une approche métabolomique, effectués sur les co-cultures, ont mis en évidence en quoi les interactions bactéries-champignons au sein de l’endomicrobiote d’algues brunes pouvaient affecter la production de médiateurs chimiques, et notamment de molécules interférant avec le quorum sensing bactérien. Ensemble, ces résultats suggèrent que le quorum sensing pourrait jouer un rôle clé dans le réseau complexe d’interactions au sein du microbiote algal, et ainsi dans l’équilibre hôte-microbioteMacroalgae host various microorganisms, collectively referred as the algal microbiota, which play an essential role in the development and health status of their host. In this work, we explored the bacterial and fungal microbiota of brown algae, as well as the impact of bacterial fungal interactions on the chemical mediation and, in particular, on the bacterial quorum sensing. Using 16S rDNA-based and ITS2-based metabarcoding approaches we showed that the fungal and bacterial communities associated with the brown macroalgae Saccharina latissima were very rich, mainly composed of few dominant OTUs, and a large abundance of “rare” OTUs. Interestingly, both fungal and bacterial communities differed from the ones of the surrounding seawater and appeared specific to the algal tissues. However, high intra and interindividual variations of composition were observed among the algal tissue samples. Thus what define the specificity of the microbial communities remains to be clarified. In parallel, we explored the chemical mediation within the cultivable endomicrobiota of four brown algae: Saccharina latissima, Laminaria digitata, Pelvetia canaliculata and Ascophylum nodosum, and pointed out that many of the isolated bacterial and fungal endophytes could synthetize metabolites interfering with bacterial quorum sensing systems, either inducing or inhibiting them. Additionally, biosensor-based bioassays coupled with metabolomics approaches performed on co-culture experiments, highlighted how bacterial-fungal interactions within the endomicrobiota of brown algae could affect the production of chemical mediators, including those interfering with bacterial quorum sensing. Altogether, the results suggest that the quorum sensing could play a key role in the complex network of interactions within the algal microbiota, and thus in the host-microbiota equilibrium
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Turner, David John. "Effects of sedimentation on the structure of a phaeophycean dominated macroalgal community." Connect to this title online, 2004. http://hdl.handle.net/2440/37702.
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Macroalgae are abundant on shallow temperate reef environments, often forming complex communities that comprise several strata. In southern Australia, these assemblages are dominated by large canopy forming taxa from the Orders Laminariales and Fucales. The presence of subtidal fucoid macroalgae differentiates these communities from that elsewhere, and emphasises the need for local studies rather than relying on generalisations made elsewhere. Like most natural systems, temperate reefs are often threatened by human activity with degradation reported from many locations in close proximity to urban settlements. The work presented in this thesis involves an examination of the temporal and spatial variability in the structure of macroalgal communities from reefs along the Adelaide (South Australia) metropolitan coast. The work looked specifically at the effects of a dispersed sediment plume, resulting from the 1997 beach sand-replenishment dredging program, on shallow sub-tidal reef systems. An examination of the structure of canopy forming phaeophycean macroalgae in Gulf St Vincent (South Australia), noted large amounts of both spatial and temporal heterogeneity. Notwithstanding, this variation was not random, but demonstrated considerable structure that could be linked to a number of important underlying processes. In particular, macroalgal assemblages appeared as a mosaic of patches, each of which comprised a high-density state clearly dominated by a single genus (Cystophora, Sargassum, or Ecklonia), or alternatively a lower density mixed assemblage (Variable Low Abundance, VLA). Macroalgal community structure appeared to be driven by biotic interactions at small scales (metres), such that patches comprised of different species of algae in high density states rarely abutted one another. Instead, VLA assemblages frequently formed a buffer being situated between these mono generic patches. In terms of successional processes, the high-density states appeared to be relatively stable whereas the VLA state, at least in some systems, was transitory. This finding was supported by the absence of intermediary high- density states (e.g. a mix of Cystophora and Ecklonia) implying that state changes must occur via the VLA state following some form of disturbance. Larger scale patterns appeared to be driven by environmental variation, with factors such as wave exposure influencing habitat suitability for individual species and thereby affecting community composition. These phenomena were examined in terms of life history strategies that tend to promote stability, and which are common in late successional taxa. The importance of properties enhancing stability and the role of disturbance was investigated experimentally using a dispersed sediment plume, which entirely engulfed two reefs, as a pulse impact. This disturbance was of particular relevance given that degradation of macroalgal communities in close proximity to the City of Adelaide has been, at least in part, attributed to the effects of elevated levels of sediment. Follow up surveys revealed that the sedimentation from the plume had primarily affected newly recruiting individuals, with few juveniles surviving to one year of age. Over the following few years, the effect of this recruitment failure cascaded into the adult stand. In broader terms, unfavourable climatic conditions prior to the start of the study, including a particularly severe El Nino event, had a widespread effect on local assemblages, causing high levels of both adult and juvenile mortality. As such, at the commencement of the study, macroalgal communities across the study area were in the process of recovery. This was observed at control sites over the duration of the study. In contrast, recruitment failure at the sediment-affected sites retarded the recovery process, exacerbating the problems associated with prior unfavourable climatic events and leaving them in a degraded state. This study demonstrated that macroalgal assemblages are equipped (under natural conditions) to handle 'normal' environmental fluctuations (such as inter-annual variability). However, the additional stress associated with certain anthropogenic impacts has the potential to push them over the limit, causing degradation. The loss of canopy macroalgae reduces the structural complexity of the system, leading to a concomitant reduction in their ability to recover. As such, these findings are of particular relevance to those charged with the responsibility for managing near-shore marine environments. The plume was created accidentally during a dredging operation for beach sand replenishment of Adelaide's eroding shoreline.Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2004.
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Fraser, Ceridwen, and n/a. "Phylogeography of the kelp genus Durvillaea (Phaeophyceae: Fucales)." University of Otago. Department of Zoology, 2009. http://adt.otago.ac.nz./public/adt-NZDU20091002.131226.
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Durvillaea, a kelp genus occurring only in the Southern Hemisphere, presents an ideal system for studies of marine connectivity and postglacial recolonisation. Durvillaea contains five currently-recognised species, four of which are non-buoyant. Whereas all non-buoyant species are restricted to the south-western Pacific, the sole buoyant species (D. antarctica) has a far wider, circumpolar distribution, strongly suggesting that long-distance dispersal in D. antarctica is achieved by rafting. This contrast in predicted dispersal ability among Durvillaea species provides an opportunity for natural phylogeographic comparisons, thereby assessing the effectiveness of rafting as a long-distance dispersal mechanism. Additionally, the inability of D. antarctica to survive in ice-affected areas, combined with its broad distribution, make it an ideal candidate for studies of postglacial recolonisation.
Phylogenetic and biogeographic relationships within Durvillaea were here assessed using sequence data from mitochondrial (COI), chloroplast (rbcL) and nuclear (18S) DNA. Genetic data were obtained from more than 500 specimens, including representatives from across the geographic range of each recognised species of Durvillaea. Mitochondrial data for Durvillaea were found to be highly phylogenetically informative, with 117 variable sites observed over a 629 bp fragment of COI. Chloroplast and nuclear markers, on the other hand, showed less variation than COI, but nonetheless contributed useful phylogenetic information. Phylogenetic analyses were performed using both Maximum Likelihood and Bayesian approaches.
Contrasting patterns of genetic diversity were observed across the range of D. potatorum in Australia, with genetic homogeneity throughout western sites versus relatively high levels of diversity in eastern populations. Based on these results, I hypothesise that D. potatorum recolonised much of the western part of its range postglacially, perhaps being entirely eliminated from western Tasmania during the last glacial period by altered oceanographic systems. Additionally, 'western' and 'eastern' D. potatorum haplotypes formed deeply-divergent clades, likely reflecting geographic isolation on either side of the Bassian Isthmus during Pleistocene marine regressions.
Substantial genetic diversity was observed across the range of the circumpolar species D. antarctica. Within New Zealand, phylogenetic and morphological analyses of D. antarctica indicate that two morphotypes ('cape' and 'thonged' forms) likely represent reproductively isolated species, with the 'cape' lineage apparently restricted to southern New Zealand. Whereas the 'cape' lineage showed little genetic variation throughout its range, the 'thonged' lineage exhibited marked phylogeographic structure, with high genetic diversity and a clear north - south genetic disjunction delineated by the Canterbury Bight.
On a broader, circumpolar scale, D. antarctica showed contrasting patterns of genetic diversity, with high levels of variation in low-latitude regions (e.g., continental coasts of New Zealand and Chile), versus near-homogeneity at high, subantarctic latitudes. These phylogeographic contrasts strongly suggest that D. antarctica recolonised much of the subantarctic region only recently, most plausibly following extirpation by ice scour at the Last Glacial Maximum (LGM). Locations of putative recolonised islands relative to 'refugial' areas indicate that Antarctic sea ice was likely more extensive at the LGM than previous studies have suggested.
Latitudinal contrasts in genetic diversity were also observed among Chilean populations of D. antarctica, with a single mitochondrial haplotype detected throughout Chilean Patagonia versus high diversity in central Chile (32�-42�S). The Patagonian populations appear to have recolonised the region postglacially, following recession of the Patagonian Ice Sheet after the LGM. These populations show transoceanic ancestry, with a closer relationship to populations in the subantarctic and southern New Zealand regions than to those in central Chile. Substantial phylogeographic structure was evident across small spatial scales in central Chile, and the correspondence of major genetic disjunctions among central Chilean sites with the presence of long stretches of unsuitable substrate (beaches) strongly suggests that habitat discontinuity drives genetic isolation in this dispersive species.
Broad-scale molecular phylogenetic analyses indicate that the current taxonomy of Durvillaea species requires substantial revision. Previously-recognised 'morphotypes' of Durvillaea (of D. potatorum in Australia, and D. antarctica in New Zealand), for example, were here found to be genetically distinct, likely representing reproductively-isolated species.
This phylogeographic research on Durvillaea kelp sheds new light on the historical impacts of climate change on Southern Hemisphere marine environments, and on the processes driving evolution in a marine macroalga.
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Silva, Daniel Lira da. "Aplicação de cromatografia gasosa acoplada à espectrometria de massas na identificação de substâncias obtidas de algas marinhas de dois estados do Nordeste brasileiro." Universidade Federal de Alagoas, 2014. http://www.repositorio.ufal.br/handle/riufal/2149.
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Seaweeds are organisms which live in oceans and seas. They have ability to perform photosynthesis and feed many species of aquatic organisms. Macroalgae, which can be divided by characteristic colors in: Red algae (Phylum Rhodopyta), Green algae (Phylum Chlorophyta) and Brown algae (Class Phaeophyceae). Seaweeds are used for centuries by Asians as an important part of their diet, and also as source of compounds to Pharmaceutical and Cosmetic industries. The Brazilian Northeastern has a large coastal area; it possesses several forms of marine organisms especially for being in a Tropical hot water zone. Based on the importance of macroalgae, a chemical study was conducted using five species of algae (Bryothamnion seaforthii; Colpomenia sinuosa; Dictyosphaeria versluysii, Digenea simplex and Galaxaura rugosa) to prepare methanolic extracts and sequential fractions. 72 substances
were identified using the GC-MS technique under the following operation conditions: helium as the carrier gas; 1.52 mL/min flow rate; oven temperature 60 º (25 ºC/min 300 ºC, heating rate); Splitless; injected volume 1 μL; solvent cutting 3 minutes. The mass spectra were obtained in the same equipment by electron impact ionization (EI) at 70 eV; and the ion source was maintained at 300 ° C. Hexadecanoic acid, in all fractions; 1-isopropyl-1,3,4-trimethyl-cyclohexane, 1,4-diisopropyl-cyclohexane and isopentyl decanoate, first identified in seaweeds; several esters, hydrocarbons and fatty acids can be mentioned as identified substances.Conselho Nacional de Desenvolvimento Científico e Tecnológico
Alga é uma forma de vida que vive em oceanos e mares e possui a capacidade de realizar fotossíntese e servir de alimento e/ou abrigo para muitas espécies de organismos aquáticos. As macroalgas, que podem ser divididas pela cor característica que possuem, em algas vermelhas (Filo Rhodophyta), verdes (Filo Chlorophyta) e pardas (Classe Phaeophyceae), são utilizadas pelos orientais como parte importante de sua alimentação há vários séculos, além de utilizá-las como fonte de produtos farmacêuticos e da indústria de cosméticos. O nordeste brasileiro possui uma vasta área litorânea e costeira sendo rico em diversas formas de vida marinha, principalmente por estar em uma zona tropical de águas quentes. Com base na importância destas macroalgas, foi realizado um estudo químico de cinco espécies de algas, Bryothamnion seaforthii, Colpomenia sinuosa, Dictyospharia versluysii, Digenea simplex e Galaxaura rugosa, através de extratos metanólicos e frações. A técnica de cromatografia gasosa acoplada à espectroscopia de massas foi utilizada com as seguintes condições de operação: hélio como gás de arraste; velocidade do fluxo, 1,52 mL/min; a temperatura inicial do forno foi 60 ºC, com uma taxa de aquecimento de 25 ºC/min até 300 ºC; “Splitless”, como modo de injeção; 1 μL de volume injetado; e corte do solvente em 3 minutos. O tempo total de corrida foi 25 minutos. Os espectros de massas foram obtidos no mesmo equipamento, através de ionização por impacto de elétrons (EI) de 70 eV; e a fonte de íons foi mantida a 300 ºC. Desse modo foram identificadas 72 substâncias, dentre as quais podem ser citadas: ácido hexadecanoico, presente em todas as frações; os hidrocarbonetos 1-isopropil-1,3,4-trimetilcicloexano, 1,4-di-isopropilcicloexano e decanoato de isopentila, identificados pela primeira vez em algas; além de diversos ésteres, hidrocarbonetos e ácidos graxos.
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Kim, Kyung-Tae. "Seasonal variation of seaweed components and novel biological function of fucoidan extracted from brown algae in Quebec." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28833/28833.pdf.
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Fucus vesiculosus et Ascophyllum nodosum sont des algues brunes comestibles et abondantes au Québec. Cependant, elles ont été négligées en raison de leur valeur potentielle inconnue et de la période de récolte limitée. Afin de valider leur utilité, la composition chimique de ces algues et l’activité inhibitrice des enzymes digestives de l'amidon par les fucoïdanes extraits de ces deux espèces d'algues ont été étudiés en fonction de la saison. Les composants principaux des algues sont dans l’ordre: les polysaccharides> minéraux> protéines> fucoïdane> lipides>> composés phénoliques, et leur quantité est très variable selon la période de récolte. F. vesiculosus contenait une plus grande quantité de protéines et de minéraux, alors que A. nodosum avait relativement plus de polysaccharides. Par conséquent, F. vesiculosus serait plus avantageux comme source d’éléments nutritifs. L’algue A. nodosum récoltée en Juillet a permis d’obtenir le fucoïdane ayant la pureté la plus élevée et le meilleur rendement. Les fucoïdanes extraits des deux espèces d’algues ont inhibé l’activité de l’α-glucosidase alors que seul celui extrait d’A. nodosum a pu, de plus, inhiber l’α-amylase. Le fucoïdane d’A. nodosum était un inhibiteur plus puissant que le fucoïdane de F. vesiculosus pour l’α-glucosidase avec des IC50 variant de 0,013 ~ 0,047 mg/ml, tout comme pour l’α-amylase avec des IC50 de 0,12 ~ 4,62 mg/mL selon le mois. Pour comprendre les facteurs clés expliquant les différences d’inhibition d’α-amylase entre les fucoïdane d’A. nodosum et F. vesiculosus, certaines caractéristiques structurales ont été analysées et comparées à du galactofucoidane qui a servi de contrôle. A partir des résultats obtenus, il est confirmé que la masse moléculaire plus faible (637 kDa) du fucoïdane d’A. nodosum et la présence de sulfates sont liées à son activité inhibitrice. Nous avons émis l’hypothèse que les faibles masses moléculaires permettent d’exposer facilement les groupements sulfate qui peuvent agir sur l’α-amylase par interaction électrostatique, et donc d'inhiber son activité. En conclusion, les algues brunes du Québec présentent un potentiel d’utilisation important pour leur valeur nutritionnelle et leurs composés bioactifs. Le fucoïdane a montré une activité d'inhibition des enzymes digestives de l'amidon (α-amylase et α-glucosidase) et cette activité est différente selon les espèces d'algues et la période de récolte. Une meilleure compréhension du mécanisme inhibiteur par le fucoïdane peut être utile afin de développer un ingrédient fonctionnel permettant de prévenir le diabète de Type-2.Fucus vesiculosus and Ascophyllum nodosum are edible brown seaweed and abundantly available in Quebec. However, they have been neglected because of their unknown value and technical limitation in harvest. In order to validate their usefulness, chemical composition in seaweeds and starch digestive enzyme inhibition activity by fucoidan extracted from two seaweed species were investigated with different seasons. The major components in both seaweeds were in order: polysaccharide > minerals > protein > fucoidan > lipid > phenol, and their quantity was quite variable depending on harvesting timing. F. vesiculosus contained larger amount of proteins and minerals, while A. nodosum had relatively more polysaccharides. Therefore, F. vesiculosus are advantageous as a nutritional source. Especially, from A. nodosum harvested in July, a fucoidan having higher purity and better yield was obtained. Fucoidans from two seaweeds species inhibited α-glucosidase activity while, only fucoidan from A. nodosum could inhibit α-amylase activity. A. nodosum fucoidan was a more potent inhibitor than F. vesiculosus fucoidan for α-glucosidase with IC50 of 0.013 ~ 0.047 mg/mL, and for α-amylase with IC50 of 0.12 ~ 4.62 mg/mL depending on harvest month. To understand the key factors explaining the difference in α-amylase inhibition between A. nodosum fucoidan and F. vesiculosus fucoidan, structural characteristic was analyzed and compared with galactofucoidan as a control. From the obtained results, it is confirmed that smaller molecular weight (637 kDa) of A. nodosum fucoidan and the presence of sulfates are related to its inhibitory activity. It is proposed that small molecular weight permits to expose easily sulfate groups for interaction with α-amylase throughout electrostatic interactions, and therefore inhibiting its activity. In conclusion, brown seaweeds in Quebec have a considerable importance for nutrition and bioactive products. Fucoidan shows the inhibition activity for starch digestive enzymes (α-amylase and α-glucosidase) and its activity is different depending on seaweed species and harvesting period. Further understanding of the inhibitory mechanism by fucoidan can be useful to develop a functional ingredient to help preventing for Type-2 diabetes.
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Haddad, Abdul-Majeid Ghalib. "On the growth and productivity of the brown alga Fucus serratus L. on the Yorkshire coast, with special reference to inorganic nutrients." Thesis, University of York, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241088.
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Heesch, Svenja, and n/a. "Endophytic phaeophyceae from New Zealand." University of Otago. Department of Botany, 2005. http://adt.otago.ac.nz./public/adt-NZDU20060901.141241.
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The aims of this study were to find endophytic brown algae in marine macroalgae from New Zealand, isolate them into culture and identify them using morphological as well as molecular markers, to study the prevalence of pigmented endophytes in a representative host-endophyte relationship, and to reveal the ultrastructure of the interface between the obligate parasite Herpodiscus durvillaeae (LINDAUER) SOUTH and its host Durvillaea antarctica (CHAMISSO) HARRIOT.
Three species of pigmented endophytic Phaeophyceae were isolated from New Zealand macrophytes. They were distinguished based on morphological characters in culture, in combination with their distribution among different host species and symptoms associated with the infection of hosts. ITS1 nrDNA sequences confirmed the identity of two of the species as Laminariocolax macrocystis (PETERS) PETERS in BURKHARDT & PETERS and Microspongium tenuissimum (HAUCK) PETERS. A new genus and species, Xiphophorocolax aotearoae gen. et sp. ined., is suggested for the third group of endophytic Phaeophyceae. Three genetic varieties of L. macrocystis as well as two varieties each of M. tenuissimum and X. aotearoae were present among the isolates. L. macrocystis and X. aotearoae constitute new records for the marine flora of the New Zealand archipelago, on genus and species level. The red algal endophyte Mikrosyphar pachymeniae LINDAUER previously described from New Zealand is possibly synonymous with Microspongium tenuissimum.
The prevalence of infection by Laminariocolax macrocystis was investigated in three populations of Macrocystis pyrifera along the Otago coast. Two of the populations situated inside and at the entrance of Otago Harbour showed high infection rates (average between 95 and 100%), while an offshore population was less infected (average of 35%).
The phylogenetic affinities of the parasitic brown alga Herpodiscus durvillaeae, an obligate endophyte of Durvillaea antarctica (Fucales, Phaeophyceae) in New Zealand, were investigated. Analyses combined nuclear encoded ribosomal and plastid encoded RuBisCO genes. Results from parsimony, distance and likelihood methods suggest a placement of this species within the order Sphacelariales. Even though H. durvillaeae shows a reduced morphology, molecular data were supported by two morphological features characteristic for the Sphacelariales: the putative presence of apical cells and the transistory blackening of the cell wall with 'Eau de Javelle'.
Ultrastructural sections showed evidence for a symplastic contact between the cells of the parasite H. durvillaeae and its host D. antarctica. Within the host cortex, parasite cells attack the fields of plasmodesmata connecting host cells. In these areas, parasite cells squeeze between the host cells and form secondary plasmodesmata connecting the primary plasmodesmata of the host cells with the cytoplasma of the parasite cell.
Moreover, despite being described as lacking pigments, H. durvillaeae possesses a rbcL gene, and its plastids show red autofluorescence in UV light, suggesting the presence of a possibly reduced, but functional photosynthetic apparatus. Vestigial walls between developing spores in the 'secondary unilocular sporangia' of H. durvillaeae confirm the identity of these sporangia as plurilocular gametangia, derived from reduced gametophytes which were entirely transformed into gametangia.
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Creis, Emeline. "Etude de la voie de biosynthèse des phlorotannins chez les algues brunes, de la caractérisation biochimique d'enzymes recombinantes à l'étude des réponses écophysiologiques." Electronic Thesis or Diss., Paris 6, 2015. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2015PA066095.pdf.
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Les phlorotannins, polymères du phloroglucinol, sont des composés phénoliques (CP) uniquement retrouvés chez les algues brunes (Phéophycées). Ces métabolites présentant des activités anti-oxydantes, interviendraient dans la formation de la paroi, mais à ce jour leur voie de biosynthèse reste non élucidée. L'annotation du génome de l'algue brune Ectocarpus, a permis d'identifier des gènes homologues codant pour des enzymes de la biosynthèse des CP chez les plantes terrestres. Une polyketide synthase de type III (PKSIII), a été caractérisée: elle synthétise le phloroglucinol. La recherche d'autres cibles a été poursuivie sur des gènes codant pour des chalcone-isomérases-like (CHIL), ainsi que pour des phénol-sulfotransférases homologues d'enzymes de sulfatation des flavonoïdes. Les CHIL se sont révélées être des fatty acid binding protein (FAP) impliquées dans le métabolisme des acides gras. L'intérêt pour cette nouvelle famille a justifié leur caractérisation biochimique puis fonctionnelle par complémentation de mutants FAP d'Arabidopsis thaliana. L'élucidation progressive des voies de biosynthèse des phlorotannins a servi de base pour étudier les mécanismes de régulation de ce métabolisme chez les Phaeophycées. En combinant des approches intégrées d'expression de gènes cibles, de dosages et de profilages de phlorotannins solubles, nous avons pu montrer que ces composés assurent une protection constitutive chez Fucus vesiculosus en réponse aux UV-B, et que leur métabolisme serait induit très précocement au cours de l'herbivorie. Le développement d'outils moléculaires spécifiques de ces voies métaboliques, ouvre de nouvelles perspectives en écophysiologie et en écologiePhlorotannins are polymers of phloroglucinol that are specific phenolic compounds of brown algae (Phaeophyceae). These metabolites present antioxidant activities and are potentially involved in the formation of cell-walls but their biosynthetic pathway is currently uncharacterized. The genome annotation of the brown algae Ectocarpus provided some information about conserved genes which are implicated in the synthesis of phenolics in terrestrial plants. One polyketide synthase of type III (PKSIII) has been successfully characterized: it produces phloroglucinol. The search for other targets has been pursued in brown algae focusing mainly on chalcone isomerase-like (CHI-like) genes, as well as on phenol-sulfotransferases, which are implicated in the sulfation of flavonoids. The characterization of CHIL has revealed their implication in fatty acid binding (FAP). However, the level of interest for this new family has led to their biochemical characterization and to functional studies by complementation of gene in the Arabidopsis thaliana FAP mutant. The progressive elucidation of the phlorotannin biosynthesis pathway has been used in order to discover mechanisms which regulate this metabolism in brown algae. By combining integrated approaches of gene expression profiling with the quantification and profiling of soluble phlorotannins, we have shown that these metabolites ensure the constitutive protection in Fucus vesiculosus against UV-B radiation and could also be induced as a very early response to grazing. The development of specific molecular tools for this metabolic pathway opens some news perspectives in ecophysiological and ecological studies
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Parys, Sabine. "Quantitative and qualitative analysis of phlorotannins of the brown algae Ascophyllum nodosum L. Le Jol. and Fucus vesiculosus L." München Verl. Dr. Hut, 2008. http://d-nb.info/990811204/04.
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Boscq, Samuel. "Establishment of the apico-basal and medio-lateral axes during the embryogenesis of the brown alga Saccharina latissima." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS673.pdf.
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Chez tous les organismes développant une architecture 3-D, des axes de croissance sont mis en place généralement au début du développement (par exemple, les axes apico-basal et dorso/ventral). Les algues brunes appartiennent au groupe phylogénétique des Stramenopiles qui est phylogénétiquement indépendant des plantes, des animaux et des champignons. Elles sont apparues il y a “seulement” 250 millions d’années, c’est-à-dire relativement récemment par rapport à l’émergence des plantes et des animaux (~ 600-700 Mya). Malgré un niveau de complexité morphologique bien inférieur à celui des plantes et des animaux, les algues brunes, et notamment les laminaires (famille des Laminariales) développent des corps de très grande taille (jusqu’à 30 mètres de long), dont l’organisation repose sur la mise en place d’axes spatiaux structurants. Pourtant, on ne sait rien de l’embryogenèse des laminaires. Ce projet a donc pour but d’étudier la mise en place des axes longitudinaux et latéraux dans les premiers stades du développement de l’embryon de l’algue Saccharina, en identifiant son déterminisme et les facteurs cellulaires impliqués dans sa mise en place. Les étapes initiales du développement de Saccharina sont les suivantes (Figure 1) : i) l’œuf (brun) de Saccharina reste attaché au tissu maternel (filaments du gamétophyte, cellule transparente). Après la fécondation, il s’allonge verticalement, et forme un empilement de cellules larges par des divisions cellulaires transversales parallèles. Il établit ainsi l’axe apico-basal. ii) dans un second temps, l’axe latéral est formé par division cellulaire orientée à 90° par rapport aux précédentes. Ceci établit l’axe latéral. Les deux axes sont maintenus pendant toute la vie de l’algue (organisme adulte). Projet : Le projet concerne 4 événements développementaux identifiés comme des étapes clés de l’embryogenèse précoce de Saccharina. a) établissement d’un axe longitudinal dans le zygote, b) polarisation du zygote, c) maintien de l’axe longitudinal dans l’embryon, d) établissement d’un axe latéral dans l’embryon Pour chacune de ces étapes clés, les questions sont les suivantes : 1) quels sont les facteurs qui déclenchent et contrôlent ces étapes (“signal” ou “déterminisme”) ? Pour les étapes précoces (zygote et embryon très précoce), nous avons abordé le rôle de l’environnement maternel, qui dans le cas présent se limite à une cellule morte maintenant l’embryon attaché au gamétophyte femelle. Pour les étapes ultérieures (embryon de 2 à 8 cellules), nous avons étudié le rôle de chaque cellule de l’embryon proprement dit dans le devenir cellulaire de leurs voisines. 2) quels sont les repères de ces étapes ? Il s’agit à la fois de facteurs de mise en œuvre (“constructeur”, “organisateur”) comme le cytosquelette, la paroi cellulaire, et de facteurs annonçant l’établissement du futur destin cellulaire et la voie de signalisation potentielle, comme le reflète le transcriptome (“code-barres”). Techniquement, le projet s’appuie principalement sur l’ablation au laser et l’excision manuelle, l’immunolocalisation (organisation de la paroi cellulaire et du cytosquelette) et la microdissection par capture laser suivie de NGS (barcode). En conclusion, le projet a fourni les premières données moléculaires et cellulaires sur les mécanismes d’établissement et de polarisation des axes au cours de l’embryogenèse d’une algue brune de la famille des Laminaires à des stades précoce post-zygotiquesIn all organisms developing a 3-D architecture, growth axes are generally established early in development (e.g. apico-basal and dorso/ventral axes). Brown algae belong to the Stramenopiles phylogenetic group, which is phylogenetically independent of plants, animals and fungi. They appeared "only" 250 million years ago, i.e. relatively recently compared with the emergence of plants and animals (~ 600-700 Mya). Despite a level of morphological complexity well below that of plants and animals, brown algae, and in particular kelps (family Laminariales), develop very large bodies (up to 30 meters long), whose organization is based on the establishment of structuring spatial axes. However, nothing is known about kelp embryogenesis. The aim of this project is therefore to study the establishment of longitudinal and lateral axes in the early stages of Saccharina algal embryo development, identifying their determinism and the cellular factors involved. The initial stages of Saccharina development are as follows (Figure 1): i) the Saccharina egg (brown) remains attached to the maternal tissue (gametophyte filaments, transparent cell). After fertilization, it elongates vertically, forming a stack of wide cells through parallel transverse cell divisions. This establishes the apico-basal axis. ii) In a second phase, the lateral axis is formed by cell divisions oriented at 90° to the preceding ones. This establishes the lateral axis. Both axes are maintained throughout the alga's life (adult organism). Project : he project concerns 4 developmental events identified as key stages in the early embryogenesis of Saccharina. a) establishment of a longitudinal axis in the zygote, b) polarization of the zygote, c) maintenance of the longitudinal axis in the embryo, d) establishment of a lateral axis in the embryo For each of these key stages, the questions are as follows: 1) what are the factors that trigger and control these stages ("signal" or "determinism")? For the early stages (zygote and very early embryo), we have discussed the role of the maternal environment, which in this case is limited to a dead cell holding the embryo attached to the female gametophyte. For later stages (embryos of 2 to 8 cells), we studied the role of each cell of the embryo itself in the cell fate of its neighbors.2) what are the milestones of these stages? These are both implementing ("constructor", "organizer") factors such as the cytoskeleton and the cell wall, and factors that herald the establishment of future cell fate and potential signaling pathways, as reflected in the transcriptome ("barcode"). Technically, the project relies mainly on laser ablation and manual excision, immunolocalization (cell wall and cytoskeleton organization) and laser capture microdissection followed by NGS (barcode). In conclusion, the project has provided the first molecular and cellular data on the mechanisms of axis establishment and polarization during embryogenesis of a brown alga of the Laminaria family at early post-zygotic stages
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Sáez, Avaria Claudio. "Physiological, biochemical, and molecular responses to copper stress in different strains of the model brown alga Ectocarpus siliculosus." Thesis, University of Plymouth, 2014. http://hdl.handle.net/10026.1/3008.
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Brown algae have been the focus of metal ecotoxicology research for over 60 years, mainly because of their high metal accumulation capacity and reputed resistance. Now that Ectocarpus siliculosus has been positioned as a model for the study of brown algae, and that the genome has been recently sequenced and annotated, new lines of research have been made possible on these ecologically and economically important organisms, including the field of ecotoxicology. Several strains of E. siliculosus have been collected and isolated from locations around the world, thus providing the opportunity to study inter-population differences in their responses to environmental stress. This investigation can be split into three main sections. In the first part Cu exposure experiments were carried out under laboratory conditions using three strains of E. siliculosus: Es524 from a Cu polluted location in Chile, REP10-11 from a metal polluted (including Cu) location in England and LIA4A from a pristine site in Scotland. Strains were exposed for 10 d to concentrations ranging between 0 and 2.4 μM Cu. We measured different parameters: relative growth rates; metal accumulation (extracellular and intracellular); phytochelatins and the expression of related enzymes; oxidative stress responses as manifested in lipid peroxidation and levels of H2O2, and levels of pigments; levels of antioxidants glutathione and ascorbate (in reduced and oxidised forms), and phenolic compounds; and the activity of the antioxidant enzymes superoxide dismutase, catalase, and ascorbate peroxidise. Strain Es524 was the most efficient in counteracting the effects of Cu stress as manifested by a combination of Cu exclusion production of metal chelators, upregulation of oxidative enzymes, and strong antioxidant metabolism. REP10-11 also showed effective Cu defences, especially related to glutathione-ascorbate interactions. LIA4A was the least tolerant strain, with metabolic defences significantly less effective against Cu exposure. In part two a novel transplantation experiment was developed to compare responses in the field with those obtained in the laboratory. The study was carried out at a metal polluted and a low-impacted site in central Chile using strain Es524 (as in the laboratory experiments) and Es147, isolated from a low metal-polluted site in Chile. From the biomass, we conducted similar measurements of Reactive Oxygen Metabolism (ROM) as for the laboratory experiments described in the first part. In agreement with the laboratory experiments, strain Es524 displayed a higher resistance to metal stress. Because they behaved similarly between strains, the best suggested biomarker candidates for future assessments are metal accumulation, glutathione and ascorbate in reduced and oxidised forms, phenolic compounds, and the activity of superoxide dismutase. The method is simple, widely applicable in temperate environments, cost-effective, and provides a reliable representation of metal bioavailability in the environment. In the final part of the study a novel technique for the co-extraction of RNA and DNA, using a high pH Tris-HCl buffer, from small amounts of biomass of different strains of E. siliculosus was successfully developed. The extraction of nucleic acids from brown algae is considered to be difficult and the product is of poor quality due to the high concentrations of interfering secondary metabolites such as phenolics and polysaccharides. The protocol devised here provided high yields of pure RNA and DNA that are suitable for molecular analyses. This investigation provides new insights on metal stress metabolism in brown algae, and demonstrates that metal resistance is dependent on inherited defences developed over a long history of exposure. Furthermore, the good agreement between the results obtained in the laboratory with those from the field study confirms that the responses expressed under controlled laboratory conditions are representative of stress metabolism of E. siliculosus under natural conditions.
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Rabillé, Hervé. "Biophysical and cellular mechanisms of tip-growth in the brown alga Ectocarpus sp." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS597.pdf.
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La croissance apicale (CA) est un mode d’élongation cellulaire extrêmement polarisée, au cours duquel la croissance en surface n’a lieu qu’à un site réduit de la cellule. Elle a lieu dans de nombreux groupes taxonomiques, et représente donc un système idéal pour des études « évo-devo » des mécanismes fondamentaux de morphogenèse cellulaire sur tout l’arbre du vivant. Néanmoins, l’étude de la CA chez les eucaryotes s’est principalement concentrée sur les plantes terrestres et les champignons, laissant de côté les autres groupes. Pour combler ce déficit de connaissances, les macroalgues brunes sont particulièrement intéressantes du fait de leur histoire évolutive unique, des spécificités de leurs structures cellulaires et des conditions physiques de leur milieu, qui ont probablement résulté en l’acquisition de mécanismes de morphogenèse originaux. Au cours de ma thèse, j’ai entrepris de caractériser les mécanismes de la CA chez Ectocarpus sp., une espèce modèle pour les algues brunes. Pour cela, j’ai mesuré le patron du taux d’expansion de la paroi à l’apex des cellules apicales, ainsi que la pression de turgescence, la courbure de surface et l’épaisseur de paroi, afin d’alimenter un modèle viscoplastique de CA. Ce modèle a permis de prédire que le patron d’extension de la paroi dans la cellule apicale n’est pas contrôlé par un gradient de propriétés mécaniques de la paroi, mais par un gradient d’épaisseur de paroi. En outre, la mesure expérimentale de la déformabilité pariétale immédiate (principalement de nature élastique) a mis en évidence un gradient inverse de déformabilité mécanique, opposé à celui qui serait attendu si cette propriété contrôlait l’aptitude de la paroi à croître. Par ailleurs, si l’abondance globale en alginates, un composant majeur de la paroi des algues brunes, semble contrôler la rigidité de la paroi où le stress de tension est élevé, les blocs mannuronates semblent aussi importants que les blocs guluronates dans cette fonction. Enfin, nous avons montré que chez Ectocarpus, les filaments d’actine (FAs) sont indispensables pour restreindre la croissance pariétale dans le dôme apical, et donc dans la mise en place de la forme tubulaire dans la région subapicale. Le marquage fluorescent des FAs a montré l’existence d’une « coiffe apicale » sous le dôme, une structure commune à plusieurs autres groupes, qui apparait nécessaire pour le renforcement mécanique de la fine paroi à l’apex. Ces données suggèrent donc que les FAs pourraient contrôler le patron d’expansion de la paroi le long de la cellule en exerçant une influence directement mécanique sur la paroi cellulaire. Dans leur ensemble, les résultats obtenus au cours de cette thèse démontrent que les mécanismes biophysiques de la CA chez Ectocarpus sont radicalement différents de ceux rencontrés chez les plantes terrestres et les champignons. À l’avenir, ils permettront la caractérisation des mécanismes moléculaires contrôlant la CA chez les algues brunes, et ouvrent ainsi la voie à de futures études évo-devo de ce mode particulier de morphogenèse cellulaireTip-growth (TG) is a universal mode of polarized cell elongation, during which the growth activity is restricted to the pole of the cell. Its wide taxonomic occurrence makes it an ideal model system for evo-devo studies of basic mechanisms of cell morphogenesis across the tree of life. Nevertheless, in eukaryotes, TG studies have mainly focused on land plants and True Fungi, leaving the over taxa largely underexplored. To fill in this knowledge gap, brown macroalgae are particularly appealing because of their unique evolutionary history, their particular cellular structures and their physical environment that have likely resulted in the acquisition of original morphogenetic mechanisms. During this thesis, I aimed to characterise the biophysical mechanisms of TG in Ectocarpus sp., a model species for brown algae. To do so, I measured the pattern of wall strain rate at the apex as well as the turgor pressure, the cell surface curvature and the wall thickness, in order to supply a viscoplastic model of TG with biological parameters. The model predicted that the wall expansion pattern in the apical cell is not determined by a gradient of wall intrinsic mechanical properties, but instead by a gradient of wall thickness. Moreover, experimental measurements of immediate wall deformability (mainly elastic) evidenced an inverted gradient of wall deformability, opposite to that expected if this property was to control the ability of the wall to expand. While the global abundance in alginates, a major component of the wall, seems to impact the wall stiffness where the stress is high, both mannuronate and guluronate blocks appeared necessary for this function. Finally, we have demonstrated that in Ectocarpus, the actin filaments (AFs) are also indispensable to restrict growth at the apical tip and so in the establishment of the tubular shape in the subapical region. Fluorescent staining of AFs showed an “apical cap” under the dome, a structure common to several other groups, that seems involved in mechanically reinforcing the thin wall at the tip. These data suggest that AFs could control the wall strain pattern along the apical cell by exerting a direct mechanical influence on the wall. Overall, the results obtained during my PhD demonstrate that the biophysical mechanism of TG in Ectocarpus is radically different from that found in land plants and fungi. They pave the way for uncovering the molecular pathways that regulate TG in this group, and thus for future promising evo-devo studies of this particular mode of cellular morphogenesis
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Damon, Eldon Pierre. "Green synthesis: the use of brown algae in the synthesis of palladium nanoparticles and applications in carbon – carbon bond formation reactions." University of the Western Cape, 2020. http://hdl.handle.net/11394/7721.
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>Magister Scientiae - MScDue to the negative impact on the environment and the associated biological risks on human and animal life, the need for eco-friendly synthetic protocols is critical. With the rapid advancement in nanotechnology, this extends to the synthesis of nanomaterials. Eco-friendly nanoparticle synthesis protocols have led to the use of fungi, plants and other biological substances, due to their remarkable ability in reducing metal ions. This led to the formation of very efficient hybrid catalysts, which are partially organic/inorganic composites. Palladium nanoparticles have drawn much interest due to its potential in catalytic applications and in photovoltaic cell development. In this study, the brown marine algae, Ecklonia radiata, was employed as a putative palladium nanoparticle bioreactor. Aqueous extracts of the algae were used as a supporting matrix for the synthesis of palladium nanoparticle (AE-PdNPs) catalysts according to the principles of green chemistry. The catalysts were then assessed for their capability in various carbon-carbon coupling reactions such as Suzuki-Miyaura, Sonogashira, and Heck coupling reactions. Selectivity studies were also performed. The PdNPs were compared to “model” polyvinylpyrrolidone palladium nanoparticles (PVP-PdNPs), synthesized according to literature methods. A variety of spectroscopic techniques were used to characterize the nanoparticles and the organic reaction products, including HRTEM, EDX, NMR, FTIR, DLS, TGA, UV-Vis, ICP-AES, GC-MS and XRD spectroscopy. qNMR was used to determine the product % yields. The aqueous extracts were characterised using NMR and a variety of assays, including total antioxidant potential, total reducing power and radical scavenging ability) to assess its ability to reduce the Pd metal salt. 2D NMR revealed polysaccharides and polyphenols to be the major and minor components, respectively, present in the extract. HRTEM images revealed the average size of the AE-PdNPs and PVP-PdNPs to be 12 nm and 8 nm, respectively. The images also showed the shapes of the NPs to be cubic for the AE-PdNPs and cubic or triangular for the PVP-PdNPs. SAED and XRD spectroscopy revealed the face-centred cubic phase and polycrystalline nature of the AE-PdNPs. No reliable data, other than the HRTEM images was obtained for the PVP-PdNPs. Zeta potential and DLS measurements confirmed the negative charge present on the surface of the nanoparticles, while the hydrodynamic radii were found to be 65 nm and 99 nm for the AE- and PVP-PdNPs, respectively, substantiating the presence of the capping agents. ICP-AES analysis revealed the Pd content of the NPs to be 48.8 and 28.9 ppm for the AE- and PVP-PdNPs. Following characterization, the PdNPs were assessed as potential catalysts in the Suzuki-Miyaura, Heck and Sonogashira carbon-carbon coupling reactions. Bromo and iodo substrates were employed, together with sterically hindered substrates, with a nitro moiety in the ortho or para positions. For the Suzuki-Miyaura reactions, both sets of PdNPs revealed slightly higher yields for the products synthesized using the bromo substrate (>90%), while low yields (40 – 55% yields) were obtained for the ortho substituted substrate in comparison to the para substrate (>90% yields). The Heck coupling reactions with butyl acrylate and 4-iodoacetphenone were successful (~70% yields), while reactions with 4-bromoacetophenone failed. However, the Sonogashira couplings did not proceed at all. With the series of reactions NPs showed some selectivity, with the AE-PdNPs consistently producing higher yields for the products obtained. This may be due to overall nature of the NPs, or due to the higher platinum loading content for the AE-PdNPs.
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Marques, Cybelle Teixeira. "?Atividade antiinflamat?ria de uma heterofucana da alga marrom Padina gymnospora." Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18531.
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?Fucans, sulfated polysaccharides extracted from brown algae and some echinoderms, have been extensively studied for its diverse biological activities and because of its interference with molecular mechanisms of cell to cell recognition, including leukocyte trafficking from blood vessels into sites of inflammation mediated by selectin, a family of adhesion molecules. In the present study, we examined structural features of a heterofucan extracted from brown algae Padina gymnospora and its effect on the leukocyte migration to the peritoneum. The sulfated polysaccharides were extracted from the brown seaweed by proteolysis with the proteolytic enzyme maxatase. The presence of protein and uronic acid contamination was detected in the crude polysaccharide extract. Fractionation of the crude extract with growing concentrations of acetone produced five fractions with different concentrations of fucose, xylose, uronic acid, galactose, glucose and sulfate. The fraction precipitated with 1.5 volumes of acetone was characterized by infrared and nuclear magnetic resonance, through which can be observed the presence of sulfate groups in the C4 of -L-fucose. The anti-inflammatory action of this composite was assessed by a sodium thioglycollate-induced peritonitis assay and through nitric oxide production by the peritoneal macrophages using Griess reagent. Fraction F1.5 was efficient in reducing leukocyte influx into the peritoneal cavity when 10 mg/kg and 25mg/kg were used, resulting in a decrease of 56 and 39%, respectively. A decrease of nitric oxide production occurred when high concentrations of fucana were used. The cytotoxicity of the composite was also assessed using the reduction of 3-(4,5 dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT). Fraction F1.5 had no cytotoxicity when 500 ?g/mL of the fraction was used. This study suggests the use of fraction F1.5 (heterofucan) as an anti-inflammatory
Fucanas, polissacar?deos sulfatados extra?dos de alga marrom e alguns equinodermos, t?m sido extensivamente estudadas devido as suas diversas atividades biol?gicas e pela sua interfer?ncia com mecanismos moleculares de reconhecimento celular, incluindo o tr?fego de leuc?citos dos vasos sangu?neos para o interior de s?tios inflamat?rios mediado pela fam?lia das mol?culas de ades?o denominada selectinas. Neste presente estudo, n?s examinamos a estrutura de uma heterofucana extra?da da alga marrom Padina gymnospora e seu efeito sobre a migra??o de leuc?citos para o perit?nio. Os polissacar?deos sulfatados foram extra?dos da alga marrom por prote?lise com a enzima proteol?tica maxatase. A presen?a de contamina??o por prote?nas e ?cido ur?nico foi detectada no extrato bruto dos polissacar?deos. Fracionamento do extrato bruto com concentra??es crescentes de acetona produziu cinco fra??es com diferentes concentra??es de fucose, xilose, ?cido ur?nico, galactose, glicose e sulfato. A fra??o precipitada com 1,5 volume de acetona foi caracterizada por infravermelho e resson?ncia magn?tica nuclear, atrav?s das quais se p?de constatar a presen?a de grupos sulfato no C4 da -L-fucose. A a??o antiinflamat?ria deste composto foi avaliada atrav?s do ensaio de peritonite induzida por tioglicolato de s?dio e atrav?s da produ??o de ?xido n?trico por macr?fagos peritoneais utilizando-se o reagente de Griess. A fra??o F1,5 mostrou-se eficiente na redu??o do influxo leucocit?rio para a cavidade peritoneal quando utilizados 10 mg/Kg e 25 mg/Kg resultando em uma diminui??o na ordem de 56 e 39 %, respectivamente. Uma diminui??o na produ??o de ?xido n?trico ocorreu quando altas concentra??es de fucana foram usadas. A citotoxicidade do composto tamb?m foi avaliada utilizando-se como par?metro a redu??o do 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). A fra??o F1,5 n?o apresentou citotoxicidade quando utilizados 500 ?g/ml da fra??o. Este estudo sugere o uso da fra??o F1,5 (heterofucana) como um antiinflamat?rio
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Saderne, Vincent [Verfasser]. "The ecological effect of CO2 on the brown algae Fucus serratus and its epibionts : from the habitat to the organismic scale / Vincent Saderne." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/1028798970/34.
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Xing, Qikun. "Deciphering the oxylipin signaling pathways during defense responses in brown macroalgae." Thesis, Sorbonne université, 2021. http://www.theses.fr/2021SORUS536.
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Les oxylipines sont des composés oxygénés dérivés d'acides gras polyinsaturés (AGPI), présents chez de nombreux organismes. Chez les plantes et les animaux, ils ont des rôles signaux dans la croissance et en réponse à divers stress. Les algues brunes ont développé des voies de biosynthèse des oxylipines uniques, à partir des AGPI en C18 et C20. Cependant, le rôle et la régulation de ces voies y sont encore peu connus. Au cours de ma thèse, j'ai mené des analyses transcriptomiques à large échelle chez deux espèces d’algues brunes, Saccharina latissima et Laminaria digitata, lors d'interactions biotiques, en relation avec l'induction des voies des oxylipines. Ces analyses ont été conduites sur des algues cocultivées avec des endophytes et en réponse à l’élicitation par les oligoguluronates. Plusieurs gènes liés à la biosynthèse des oxylipines montrent des régulations différentes. Après l’élicitation, un gène codant potentiellement pour un cytochrome P450 (CYP) est surexprimé à 1 h et 12 h, suggérant une induction séquentielle des voies des oxylipines chez S. latissima. Des profilages métaboliques montrent l’accumulation précoces d’oxylipines issues de la voie des AGPI en C18 et suggèrent le rôle alternatif de composés dérivés des AGPI en C20. Enfin, le rôle biologique de plusieurs oxylipines et aldéhydes a été étudié sur la régulation de certains gènes cibles ou l'accumulation de composés putatifs de défense chez S. latissima et L. digitata. Les résultats de ces travaux ont permis de reconstruire partiellement les voies des oxylipines et de mieux comprendre leur régulation lors des réponses de défense chez les algues brunesOxylipins are oxygenated compounds derived from polyunsaturated fatty acids (PUFAs), found in many organisms. In land plants and animals, they are known to have regulating roles in growth and in response to various stresses. Brown algae have developed unique oxylipin pathways, using both C18- and C20- type PUFAs. However, the role and regulation of oxylipin pathways during defense responses are largely unclear in brown algae. In my PhD thesis, I conducted large transcriptomic analyses in order to decipher the molecular responses of two kelps species, Saccharina latissima and Laminaria digitata during biotic interactions, in relationships with the induction of oxylipin pathways. The transcriptomic analysis was performed on a kelp-endophyte co-cultivation bioassay and oligoguluronate elicitation. Among differentially expressed genes, several genes putatively involved in oxylipin pathways were identified with diverse expression patterns. During the elicitation, one putative cytochrome P450 (CYP)-encoding gene was induced at 1 h and 12 h, suggesting that oxylipin pathways in S. latissima might be induced at least two times. The result of metabolite profiling showed an early production of putative C18 oxylipins and the putative alternative role of C20 oxylipin pathways during the elicitation. Finally, the biological function of several oxylipins and aldehydes were tested on targeted gene or metabolite inductions in S. latissima and L. digitata. Altogether, these results led to the partial reconstruction of oxylipin pathways and provide a better understanding of their regulation during defense responses in kelps
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Bonin, Patricia. "Etude du métabolisme du mannitol chez l'algue brune modèle Ectocarpus siliculosus : caractérisation de l'enzyme clé mannitol-1-phosphate déshydrogénase." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066618/document.
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Les algues brunes sont des organismes photosynthétiques multicellulaires, appartenant à la lignée des straménopiles, et dont l'habitat principal est la zone intertidale. Une de leurs caractéristiques métaboliques est d'utiliser le mannitol (polyalcool à six atomes de carbone) comme forme de stockage du carbone issu de la photosynthèse. Le métabolisme du mannitol chez ces organismes fait intervenir quatre enzymes, deux pour la synthèse et deux pour le recyclage, regroupées dans le cycle du mannitol. Parmi les algues brunes, Ectocarpus siliculosus est l'organisme modèle pour étudier différents aspects de leur biologie. Au cours de la thèse, trois gènes de cette algue codant pour les enzymes responsables de la première étape du cycle du mannitol, la mannitol-1-phosphate déshydrogénase (M1PDH), ont été étudiés (EsM1PDH1, EsM1PDH2, et EsM1PDH3). Les M1PDHs catalysent une réaction réversible entre le fructose-6-phosphate et le mannitol-1-phosphate. Une version du gène EsM1PDH, codant pour une protéine tronquée en N-terminal afin d'éliminer un domaine de fonction inconnue, a été surexprimée chez la bactérie Escherichia coli. La protéine recombinante tronquée a été purifiée et caractérisée au niveau biochimique, notamment pour déterminer ses paramètres cinétiques dans les deux sens de la réaction catalysée par les M1PDHs. Ces résultats ont été complétés par l'analyse de l'expression des gènes codant pour les enzymes du cycle du mannitol chez E. siliculosus au cours du cycle diurnal. L'ensemble de ces observations contribue à mieux comprendre une voie métabolique clé dans la physiologie des algues brunesBrown algae are multicellular photosynthetic organisms belonging to the stramenopile lineage and which are mainly found in the intertidal zone. One of their metabolic characteristics is to store carbon fixed by photosynthesis through the production of mannitol, a 6-carbon non-cyclic polyol. Synthesis and recycling of mannitol in these organisms occur through the mannitol cycle, which includes two steps for synthesis and two for recycling. Among brown algae, Ectocarpus siliculosus represents the model organisms to study different aspects of their biology. During the PhD thesis, three genes coding for the enzymes involved in the first step of the mannitol cycle, the mannitol-1-phosphate dehydrogenase (M1PDH), were studied (EsM1PDH1, EsM1PDH2, and EsM1PDH3). M1PDHs catalyze a reversible reaction between fructose-6-phosphate and mannitol-1-phosphate. One modified version of the EsM1PDH1 gene, coding for a N-terminal truncated protein in order to deleted a domain of unknown function, was overexpressed in the bacteria Escherichia coli. The truncated recombinant protein was purified and biochemically characterized, notably to determine kinetic parameters in both directions of the reversible reaction catalyzed by M1PDH. These results were completed by analysis of changes in expression of genes encoding enzymes involved in the mannitol cycle during the diurnal cycle. These observations contribute to increasing the understanding of a key metabolic pathway in brown algal physiology
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Theodorou, Ioannis. "Cell fate and blade patterning during the early growth of Saccharina latissima sporophytes." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS013.pdf.
Full textAbstract:
Saccharina latissima est un organisme photosynthétique multicellulaire parenchymateux du groupe des algues brunes (Phaeophyceae). Cette algue appartient au groupe des “kelps” (Laminariales), un groupe qui a récemment acquis une grande importance économique et écologique. En particulier, nos connaissances sur Saccharina et les autres laminaires sont limitées à leurs caractéristiques physiologiques et écologiques, tandis que notre compréhension de leur développement est pour la plupart dépassée ou incomplète. En ce qui concerne leur cycle de vie, il est diplobiontique avec des générations hétéromorphes. Plus précisément, la phase du cycle de vie prédominante à la fois dans le temps et l’espace, est le sporophyte. Le stade microscopique est quant à lui représenté par deux gamétophytes dioïques. Le zygote se transforme en sporophyte en quelques mois, mais ce processus est largement inconnu. Le but de ce projet est d'élucider la morphogenèse des embryons de Saccharina latissima. Tout d'abord, nous avons identifié trois phases principales basées sur les axes de croissance de l'embryon. La phase I démarre par la polarisation du zygote et se poursuit par une séquence de divisions transversales anticlinales perpendiculaires à l'axe de croissance principal. Ensuite, des divisions longitudinales anticlinales ont lieu pendant la phase II, conduisant à la formation d'une grille monostromatique faite de cellules en forme de cuboïdes alignés en croix. Le troisième axe de croissance est introduit pendant la phase III, en même temps que l'émergence de différents types de tissus, un processus défini comme la polystromatisation. Après l'identification des différentes phases de développement embryonnaire, une étude morphométrique a été réalisée en phase II. Des paramètres quantitatifs morphométriques tels que la vitesse et l'orientation de la division cellulaire ainsi que la forme et la direction de l'expansion des cellules ont été recueillis. Ces données sont enrichies par la caractérisation du cytosquelette et de la paroi cellulaire. Pour ce faire, différentes approches de microscopie ont été utilisées. D’abord, les modèles de division et d'expansion cellulaires pendant l'embryogenèse de Saccharina ont été extraits de suivis de croissance des embryons par microscopie “time-lapse”. De plus, les techniques de marquage fluorescent ont été utilisées pour mesurer la rigidité de la paroi cellulaire pendant un choc hyperosmotique ainsi que pour explorer la structure du cytosquelette. En outre, une approche transcriptomique sur les embryons de Saccharina a eu lieu pour identifier les gènes régulateurs clés. Un modèle mécanistique a été construit pour rendre compte du patron de développement, impliquant une anisotropie mécanique de la paroi cellulaire. La structure du cytosquelette est également unique et joue potentiellement un rôle important pendant la phase II. Au cours de la phase III, la différenciation cellulaire se déplace de façon centripète tandis que la polystromatisation se déplace de façon acropète à partir de la base de l'embryon. La lame et le stipe formés sont constitués des mêmes types de cellules, mais leur distribution est différente. Par exemple, les parties polystromatiques plus anciennes présentent une grande abondance de cellules médullaires qui sont totalement absentes des parties polystromatiques plus jeunes. En revanche, ces dernières régions sont riches en cellules corticales. Enfin, notre analyse transcriptomique indique une forte répression génique entre la phase II et la phase III, en particulier des gènes impliqués dans la signalisation cellulaire liés au développement parenchymatique. Les embryons de Saccharina sont un système morphogénétique unique avec une géométrie et un alignement cellulaire particuliers. En comparaison avec la structure et la mécanique des tissus des plantes terrestres, les “kelp” ont exploité un ensemble de principes différentsSaccharina latissima is amulticellular parenchymatic photosynthetic organism in the group of brown algae (Phaeophyceae). It belongs specifically to the group of kelps (Laminariales), a group that has recently ac-quired great economic and ecological importance.Notably, our knowledge for Saccharina and the other kelps is restricted to their physiological and ecological traits while our understanding on their development is mostly outdated or incomplete. Their life cycle is diplobiotic with heteromorphous generations. Specifi-cally, the large and conspicuous plant is the sporophyte, and the microscopic stage is represented by two dioecious gametophytes.The early development of the sporophyte is a largely unknown process.The aim of this project was to elucidate the morphogenesis of Saccharina latissima’s embryos from de-scriptive and mechanistic point of view. First, we identified three main phases based on the body axes of the embryo. Phase I follows the formation of the polarised zygote, characterised by a sequence of anticli-nal transverse divisions perpendicular to the main growth axis.Then, longitudinal anticlinal divisions take place during Phase II, leading to the formation of a monostromatic grid mad of cross-aligned cuboid cells. The third growth axis is introduced during Phase III, together with the emergence of different types of tis-sue, a process defined as polystromatisation. Then (Paper I), a morphometric study was performed in Phase II. Morphometric quantitative parameters like cell division rate and orientation as well as cell shape and direction of expansion were collected and combined with hyperosmotic treatments to test simulations derived from vertex modelling. Simulations suggest that anisotropic patterns on cell wall (CW) stiffness explain the 2D morphogenesis of the embryo. Next (Paper II), we postulated that these patterns could be underlied by a specific organisation of the cytoskeleton. Observations on actin labelling show an aniso-tropic actin filaments (AFs) organisation at the cortex below the anticlinal CWs. Specifically, the cortical AFs are parallel to the future third growth axis. In contrast, the AFs below the walls of the front and rear surfaces seem isotropic. Drug treatments did not assist to establish a functional link between the CW stiff-ness and AF patterns. However, AFs potentially restrict cell growth along a 2D plane. We postulate that this pattern of AFs organisation needs to be rearranged for allowing cell growth and division along the three spatial axes, and therefore, to allow thickening of the so far monolayer lamina. Furthermore, we focused on the cellular and molecular events leading lamina thickening (Phase II to – Phase III transition). At the molecular level (Paper IV), transcriptomic analysis during the initiation of Phase III detected a downregula-tion of most of the differentially expressed genes. In addition, GO analysis indicates a switch of gene ex-pression towards signaling and post-translational modifications. However, a direct relation between the patterns of gene expression and the addition of a third growth axis has not been established.At the cellular level (Paper III),semithin sections elucidated the patterns of 3D growth and cell differentiation. Specifical-ly, polystromatisation (thickening) and cell differentiation occurs centripetally from an external epidermal meristem and propagates acropetally from the base of the embryo. Different regions of the developing thallus present different morphometries and abundance of the different cell types. For example, the older polystroma is rich in medullary elements and poor in cortical cells, and the inverse is observed in younger polystroma.My project formulates a morphogenetic model for Saccharina’s embryos, based on simple cellular me-chanics. Anisotropic patterns explain how the embryos acquire their initial shape which is the scaffold for the late 3Dgrowth accompanied by tissue emergence and a superficial meristem
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Pessia, Eugénie. "Comment le X vient-il à la rescousse du Y ? : évolution de la compensation de dosage des XY humains et autres questions sur l'évolution des chromosomes sexuels eucaryotes." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10261/document.
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Un premier pan de ma thèse concerne deux différents mécanismes de sauvetage du Y par le X. Premièrement, j'ai participé à une controverse sur la compensation de dosage chez les mammifères. Une hypothèse avait été proposée dans les années 60 par Susumo Ohno, proposant un mécanisme de compensation en deux temps. Chez les mâles, la perte de nombreux gènes sur le Y entraîne un déséquilibre de dosage car ces gènes qui étaient précédemment présents en deux copies sont devenus unicopie, soit une division d'expression par deux. Selon l'hypothèse d'Ohno, chez les mammifères en réponse à cela le X aurait doublé son expression, mais dans les deux sexes menant ainsi à une expression trop élevée chez les femelles. Ce deuxième problème de dosage aurait alors été résolu par la mise en place d'une inactivation aléatoire de l'un des deux X chez les femelles. Tandis que la deuxième partie de l'hypothèse d'Ohno, l'inactivation du X, a été très étudiée, la première partie est restée spéculative jusqu'aux années 2000. En étudiant des données d'expression du X humain j'ai pu montrer, de manière concomitante avec d'autres auteurs, que la première partie de l'hypothèse d'Ohno n'est pas totalement vraie car seule une partie des gènes sont sur-exprimés. J'ai ensuite participé à l'écriture d'une revue visant à donner une explication alternative à la compensation de dosage pour l'évolution de l'inactivation du X chez les femelles mammifères. Deuxièmement, j'ai étudié la présence de conversion génique X-Y dans plusieurs gènes, au sein de nombreuses espèces de primates. Mes travaux me mènent à discuter le fait que ce type d'évènement soit effectivement favorisé par la sélection. Je pose l'hypothèse que ces conversions géniques ont été maintenues de manière neutre. Ces deux travaux ne vont pas dans le sens d'un chromosome X sauvant le Y avec beaucoup de zèle. Dans un dernier temps, m'éloignant des espèces modèles, j'ai étudié les chromosomes sexuels particuliers d'une algue brune : Ectocarpus siliculosus. Cela m'a permis de vérifier si le scénario évolutif actuel des chromosomes sexuels est toujours valide dans un groupe d'eucaryotes séparé des animaux depuis plus d'un milliard d'annéesThe first part of my thesis concerns two different mechanisms of the Y being rescued by the X. Firstly, I contributed to a controversy on mammalian dosage compensation. During the 60s Susumo Ohno hypothesized a two-step dosage compensation mechanism. In males, the high loss of Y-linked genes led to a dosage imbalance: these genes were previously present in two allelic copies and became unicopy, meaning that their expression has been halved. According to Ohno’s hypothesis, in response to this imbalance the mammalian X would have doubled its expression in the two sexes, resulting in a to high expression in females. This second dosage imbalance would have been resolved by the random inactivation of one of the two Xs in females. Whereas the second part of Ohno’s hypothesis, the X-chromosome inactivation, has been well studied, the first part remained speculative until the 2000s. I studied human X-linked expression data and was able to show, concomitantly with other authors, that the first part of Ohno’s hypothesis is not totally true as only some of the X-linked genes are hyperexpressed. I later participated in the writing of a review aiming to give an alternative hypothesis for the evolution of X-chromosome inactivation in mammalian females than dosage compensation. Secondly, I studied signatures of X-Y gene conversion in several genes within numerous primate species. Myresults led me to discuss if these events were indeed selected for. I hypothesize that these gene conversion events occurred in a neutral manner. These two different studies suggest that the X chromosome may not be as much a help for the Y as has been suggested. Lastly, moving away from model species, I studied the peculiar sex chromosomes of a brown alga: Ectocarpus siliculosus. This work allowed me to test if the current hypotheses on sex chromosome evolution still hold in a eukaryotic group that diverged from animals more than one billion years ago
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Piarulli, Stefania. "Divergence patterns in Fucus seaweeds (Phaeophyceae) in the northern Baltic Sea and in the Tjongspollen area." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9544/.
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To be able to interpret patterns of biodiversity it is important to understand the processes by which new species evolve and how closely related species remain reproductively isolated and ecologically differentiated. Divergence and differentiation can vary during speciation and it can be seen in different stages. Groups of closely related taxa constitute important case studies to understand species and new biodiversity formation. However, it is important to assess the divergence among them at different organismal levels and from an integrative perspective. For this purpose, this study used the brown seaweeds genus Fucus as a model to study speciation, as they constitute a good opportunity to study divergence at different stages. We investigated the divergence patterns in Fucus species from two marginal areas (northern Baltic Sea and the Tjongspollen area), based on phenetic, phylogenetic and biological taxonomical criteria that are respectively characterised by algal morphology, allele frequencies of five microsatellite loci and levels of secondary polyphenolic compounds called phlorotannins. The results from this study showed divergence at morphological and genetic levels to certain extent but complete lack of divergence at biochemical level (i.e. constitutive phlorotannin production) in the Baltic Sea or Norway. Morphological divergence was clearly evident in Tjongspollen (Norway) among putative taxa as they were identified in the field and this divergence corresponds with their neutral genetic divergence. In the Baltic, there are some distinguishable patterns in the morphology of the swedish and finnish individuals according to locality to certain extent but not among putative taxa within localities. Likewise, these morphological patterns have genetic correspondence among localities but not within each locality. At the biochemical level, measured by the phlorotannin contents there were neither evidence of divergence in Norway or the Baltic Sea nor any discernable aggregation pattern among or within localities. Our study have contributed with further understanding of the Baltic Sea Fucus system and its intriguingly rapid and recent divergence as well as of the Tjongspollen area systems where formally undescribed individuals have been observed for the first time; in fact they appear largely differentiated and they may well warrant a new species status. In current times, climate change threatens, peripheral ecosystems, biodiversity, and increased knowledge of processes generating and maintaining biodiversity in those ecosystems seem particularly important and needed.
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Guéno, Josselin. "Détermination et différenciation sexuelle chez les algues brunes." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS629.
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Chez de nombreux eucaryotes, le sexe est déterminé génétiquement par des chromosomes sexuels tels que XY, ZW et UN. Chez de nombreuses algues brunes, le sexe est déterminé génétiquement par les chromosomes IJ et V, plus précisément par la présence de régions spécifiques U (femelles) ou V (mâles) sur ces chromosomes. Un gène candidat pour la détermination du sexe mâle a été découvert dans la région spécifique du chromosome V. Ce gène appartient à la famille des gènes codant pour les protéines à domaine HMG, qui intervient notamment dans la détermination du sexe chez les mammifères et les champignons. Bien que la détermination du sexe soit déclenchée par un gène présent sur les chromosomes sexuels, la différenciation sexuelle est principalement déterminée par l'expression de gènes sexuellement biaisés au niveau des autosomes, qui sont donc présents chez les mâles et les femelles, mais dont le niveau d'expression diffère entre les deux sexes. Le but de ma thèse était d'améliorer notre compréhension des mécanismes qui sous-tendent la détermination et la différenciation du sexe chez les algues brunes. J'ai étudié la protéine HMG liée à la région spécifique mâles chez Ectocarpus, par des techniques de double hybride en levures et de DAP-seq. Par ailleurs, afin de comprendre comment les programmes de développement sexuel sont établis et régulés chez les algues brunes, j'ai examiné les paysages chromatiniens entre les deux sexes à différentes échelles que ce soit au niveau du génome, au niveau chromosomique et au niveau des gènes sexuellement biaisés par une méthode ChlP-seq contre des modifications post-traductionnelles d'histoneIn many eukaryotes, sex is genetically determined by sex chromosomes such as XY, ZW and IJIV. In many brown algae, sex is genetically determined by the U and V chromosomes, more precisely by the presence of U (female) or V (male)-specific regions on these chromosomes. A candidate gene for male sex deterrnination has been discovered at the V (male)-specific region. This gene belongs to the HMG-domain protein coding gene family, that is involved in gender determination in mammals and fungi. Although sex determination is triggered by a gene present on the sex chromosomes, sexual differentiation is mainly driven by autosomal sex-biased gene expression, which are therefore present in both males and females. My thesis's goal was to increase our understanding of the mechanisms underlying sex determination and differentiation in brown algae. I studied the HMG protein linked to the (male)-specific regions in Ectocarpus, by a yeast two hybrid method and DAP-seq. In order to understand how sex-specific developmental programs are established and regulated in the brown algae, I examined the sex- and chromosome-specific chromatin landscapes by a ChlP-seq method, and explored variant lines that are impaired in the expression of their sex-specific developmental programs
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Álvarez, García Daniel, Salazar Enrique Alberto Cebreros, Ludeña Yenifer Carolina Herrera, Vásquez María Angélica Herrera, and Monrroy Mariafe Jazmín Sayas. "Proyecto Aurora." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/655422.
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En el presente trabajo de investigación se analizan todos los aspectos necesarios para iniciar un proyecto de negocio basado en la elaboración y comercialización de productos de cuidado personal hechos a base de algas pardas, mayormente conocido como sargazo. Este insumo brinda colágeno, hidrata y contiene vitaminas beneficiosas para la piel, por lo que es adecuado recibir sus nutrientes a través de productos de uso rutinario.
Actualmente, el mercado de productos de higiene y cuidado personal se encuentra en crecimiento por la situación actual de la pandemia del COVID-19, por lo que la población ha priorizado el consumo de productos que le aseguren limpieza y cuidado. Adicionalmente, ya existía una tendencia a utilizar productos que contengan insumos naturales para el cuidado de la piel, por lo que un negocio con estas características tiene valor agregado frente a las otras empresas del mercado actual en Perú.
A partir de las situaciones planteadas nace Aurora, negocio de productos de cuidado personal hechos a base de algas pardas en presentación de jabón y crema hidratante. Aurora cubre las necesidades de este tipo de productos de los usuarios de nivel socioeconómico A/B y C de las zonas 6 y 7 de Lima Metropolitana. Se estima que su tamaño de mercado inicialmente es de 432 649 personas, con un crecimiento anual del 6%. Para el inicio de sus operaciones se necesita una inversión inicial de S/ 14 869,26, la cual le permitirá adquirir los recursos necesarios para la producción y comercialización del producto.This research work analyzes all the necessary aspects to start a business project based on the development and commercialization of personal care products made from brown algae, mostly known as sargassum. This input provides collagen, hydrates and contains beneficial vitamins for the skin, so it is appropriate to receive its nutrients through products for routine use. Currently, the market for hygiene and personal care products is growing due to the current situation of the COVID-19 pandemic, so the population has prioritized the consumption of products that ensure cleanliness and care. Additionally, there was already a tendency to use products that contain natural ingredients for skin care, so a business with these characteristics has added value compared to other companies in the current market in Peru. From the situations raised, Aurora was born, a business of personal care products made from brown algae in a presentation of soap and moisturizer. Aurora covers the needs of this type of product for users of socioeconomic levels A / B and C in zones 6 and 7 of Metropolitan Lima. It is estimated that its market size initially is 432 649 people, with an annual growth of 6%. An initial investment of S / 14,869.26 is required to start its operations, which will allow it to acquire the necessary resources for the production and commercialization of the product.
Trabajo de investigación
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Mazéas, Lisa. "Métabolisme des polysaccharides de la matrice extracellulaire chez les algues brunes : histoires évolutives et approches protéomiques." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS597.
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Les algues brunes appartiennent à la lignée des Straménopiles, qui regroupe également divers protistes, diatomées et oomycètes. Elles sont les seules à avoir développées une multicellularité complexe dans cette lignée, et ceci indépendamment d'autres lignées, comme celles comprenant les plantes et les animaux. L’acquisition convergente de la multicellularité s’est accompagnée du développement d’une matrice extracellulaire (MEC), qui grâce à ses propriétés adhésives, a joué un rôle dans cette transition. La MEC est impliquée dans de nombreux rôles biologiques, tels que le maintien de l’intégrité cellulaire, le développement ou les réponses de défenses. Ces fonctions sont intimement liées à la composition chimique de la MEC, essentiellement constituée de polysaccharides chez les algues brunes. Les principaux polysaccharides sont les alginates et les polysaccharides sulfatés contenant du fucose (FCSP), ces derniers regroupant fucanes et fucoïdanes. La biosynthèse de ces composés doit être finement orchestrée pour permettre l’agencement de la MEC, mais à ce jour il existe très peu de données sur leur métabolisme chez les algues brunes. L’analyse du 1er génome d’algue brune en 2010 avait permis de retracer les voies de synthèses des alginates et des fucanes, néanmoins une vue plus exhaustive à l’échelle des différents groupes d’algues brunes manquait pour affiner les prédictions. De même, la localisation subcellulaire des lieux de synthèse restait peu explorée. Dans le cadre de cette thèse, j’ai abordé plusieurs approches pour étudier les enzymes impliquées dans le métabolisme des alginates et des FCSP chez les algues brunes. Tout d’abord, j’ai pu bénéficier de l’accès à un grand nombre de génomes d’algues brunes (40) récemment séquencés et accessibles au laboratoire. Par des approches in silico, j’ai pu annoter les enzymes impliquées dans le métabolisme des polysaccharides de la MEC, dont les Carbohydrate Actives enZymes (CAZymes). Ceci m’a permis de mettre en lumière l’originalité du contenu en CAZymes chez les algues brunes, d’affiner les prédictions de gènes candidats dans la synthèse des fucanes (fucosyltransférases, sulfotransférases), tout en retraçant l’histoire évolutive de l’alginate au sein des Straménopiles. Dans une seconde approche, j’ai travaillé à la mise en place d’un protocole pour l’isolement de l’appareil de Golgi chez les algues brunes, afin d’identifier des enzymes potentiellement impliquées dans la synthèse des FCSP. Cette tâche s’est révélée particulièrement difficile, mais un fractionnement partiel a pu être validé. Les analyses protéomiques de ces fractions, confrontées aux analyses moléculaires, m’ont permis d’affiner nos candidats cibles dans la synthèse des fucanes, pour lesquels j’ai initié un travail d’expression hétérologue. Ces recherches nous ont permis de progresser dans la connaissance des voies métaboliques des polysaccharides de la MEC chez les algues brunes, et constituent une assise solide pour les futures recherches de validations fonctionnelles dans ce domaineBrown algae belong to the Stramenopiles lineage, which also includes various protists, diatoms and oomycetes. They are the only organisms in this lineage to have developed complex multicellularity, independently of other lineages, such as those containing plants and animals. The convergent acquisition of multicellularity was accompanied by the development of an extracellular matrix (ECM), whose adhesive properties played a role in this transition. The ECM is involved in many biological functions, such as the maintenance of cellular integrity, development and defense responses. These functions are closely linked to the chemical composition of the ECM, which in brown algae is mainly composed of polysaccharides. The main polysaccharides are alginates and fucose-containing sulfated polysaccharides (FCSPs), the latter including fucans and fucoidans. The biosynthesis of these compounds must be finely orchestrated to enable the assembly of the ECM, but to date there is very little data on their metabolisms in brown algae. The analysis of the first brown algal genome in 2010 allowed to trace the biosynthetic pathways of alginates and fucans, but we still lack a more exhaustive overview of different groups of brown algae to refine these predictions. Similarly, the subcellular location of the synthesis sites has not been fully explored. During my PhD, I used several approaches to study the enzymes involved in the metabolism of alginate and FCSPs in brown algae. First, I had the chance to have access to a large number of recently sequenced brown algal genomes (40) available in the laboratory. Using in silico approaches, I was able to annotate the enzymes involved in the metabolism of ECM polysaccharides, including the Carbohydrate Active enZymes (CAZymes). This allowed me to highlight the originality of the CAZyme content in brown algae, to refine the predictions of candidate genes involved in fucan synthesis (fucosyltransferases, sulfotransferases), and to trace the evolutionary history of alginate in Stramenopiles. In a second approach, I worked on establishing a protocol to isolate the Golgi apparatus in brown algae, in order to identify enzymes potentially involved in the synthesis of FCSPs. This was a particularly difficult task, but validation of partially enriched fractions was possible. Proteomic analyses of these fractions, combined with molecular analyses, allowed me to refine our candidate genes for fucan synthesis, for which I have initiated heterologous expression. This research has advanced our understanding of the metabolic pathways of ECM polysaccharides in brown algae, and provides a solid foundation for future functional validations
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Morrell, S. L. "Biological investigations into the brown alga Sargassum muticum." Thesis, University of Portsmouth, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374873.
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Cabioch, Léa. "Chemical signaling and defense in brown algal kelps during interactions with herbivores." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066708/document.
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Les kelps sont des espèces clés dans les écosystèmes marins tempérés, elles vivent en milieu intertidal le long des côtes où elles sont souvent exposées à des herbivores. Comme la plupart des organismes sessiles, les kelps ont développé des stratégies de défense contre l’herbivorie. Chez la laminaire Laminaria digitata, l’élicitation par les oligoguluronates induit des régulations transcriptomiques et l’activation de voies métaboliques, menant à la production et la libération de métabolites dans l’environnement, tels que des aldéhydes. De plus, cette espèce d’algue brune a montré des réponses systémiques suite à une élicitation. Des composés solubles dans l’eau de mer environnant les forêts de laminaires peuvent aussi modifier leur physiologie en réponse à l’élicitation. Une telle signalisation chimique à distance lors des réponses de défense rappelle les phénomènes de protection systémique et de potentialisation chez les plantes. Dans les forêts de laminaires, celle-ci pourrait jouer un rôle écologique majeur dans la structuration des algues marines et des communautés d’herbivores. Dans le contexte des interactions kelp/herbivores, nous avons étudié les réponses de défense et les processus de signalisation chez deux espèces emblématiques de laminaires originaires des côtes atlantiques et du Pacifique Sud, impliquées dans des interactions spécialisées avec leurs herbivores, L. digitata en interaction avec Patella pellucida (Bretagne, France) et Lessonia spicata avec Scurria scurra (Chili). Des approches combinées de métabolomique et de bio-essais ont été réalisées pour élucider la nature de potentiels signaux chimiques et leurs rôles biologiques et écologiques dans la défense des algues face aux herbivores. Les résultats ont montré que, en réponse à un broutage, les kelps présentent des modifications métaboliques telles que l’induction de voies de biosynthèse des acides gras, des oxylipines et d’acides aminés, ainsi que des modifications transcriptomiques. De plus, nous avons constaté que les laminaires co-incubées avec des algues broutées présentaient des changements de leur endo-métabolome en comparaison à des algues broutées, et semblaient moins consommées lors d’un broutage ultérieur, suggérant une perception et une intégration des composés algaux induits par l’herbivorie par les algues voisines. Des études de terrain et en laboratoire ayant précédemment mis en évidence une libération massive d’aldéhydes dans l’air et l’eau de mer après des stress biotiques et abiotiques, nous avons exploré les rôles biologiques d’une signalisation de type aldéhyde dans les interactions kelp/herbivores. Nous avons montré que les aldéhydes pouvaient modifier le métabolisme d’une algue par l’activation du métabolisme des acides gras, et que l’application de 4-HHE sur L. digitata pouvait réduire significativement une consommation algale ultérieure par les herbivores. Ainsi, ces résultats participent à une meilleure compréhension des réponses de défense suite à un broutage chez les laminaires, et confortent l’existence d’une signalisation à distance dans les interactions avec les herbivores, qui impliquerait des composés de défense émis par les algues, dont les aldéhydesKelps are founding species of temperate marine ecosystems, they evolve in the intertidal coastal areas where they are often challenged by herbivores. As most of sessile organisms, kelps develop defensive strategies against herbivory. In the kelp Laminaria digitata, elicitation by oligoguluronates induced regulations of transcription and metabolic pathways, leading to production and release of metabolites, such as aldehydes, in the environment. Moreover, this kelp species feature systemic responses upon defense elicitation and waterborne compounds surrounding a kelp bed have shown to modify its defense physiology. Such distant chemical signaling during defense responses are reminiscent of systemy and priming mechanisms in plants. In marine kelp beds, it should have a major ecological role in structuring marine algal and herbivore communities. In the context of kelp/herbivore interactions, we investigated the defense responses and signaling processes in two emblematic kelp species from north Atlantic and South Pacific coasts, involved in specialized interactions with their herbivores, L. digitata in interaction with Patella pellucida (Brittany, France) and Lessonia spicata with Scurria scurra (Chile). Combined approaches of metabolomics and bio-assays were carried out to decipher the nature of the putative chemical cues, and their biological and ecological roles in algal defense against herbivores. Results showed that, in response to grazing, kelps featured metabolic modifications such as induction of fatty acids, oxylipins and amino acids biosynthetic pathways, as well as transcriptomic modifications. Moreover, we observed that kelps co-incubated with grazed algae exhibited endo-metabolome changes compared to grazed one, and seemed to be less consumed during a subsequent grazing, suggesting the perception and integration of herbivory-induced algal compounds in neighboring algae. As field and lab studies previously highlighted a strong release of aldehydes into the air and the seawater following biotic and abiotic stresses, we further explored the biological roles of aldehyde-based signaling in kelp/herbivore interactions. We found that aldehydes could modify algal metabolism, including the activation of fatty acid metabolism, and that the application of 4-HHE on L. digitata could significantly reduce later algal consumption by herbivores. Thus, these results contribute to a better understanding of defense responses following grazing in kelps, and revealed the occurrence of distance signaling during interaction with herbivores, which could involve algal emitted compounds, such as aldehydes
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Jones, A. D. G. "The biodegradation of pollutants by the chrysophyte alga Ochromonas danica, and aspects of its nutritional ecology." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285359.
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Serebryakova, Alexandra. "Acclimation and adaptation of invasive seaweeds - a case study with the brown alga sargassum muticum." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066475.
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Les algues non-indigènes ont des impacts sur les communautés naturelles à une échelle mondiale: elles affectent la biodiversité et le fonctionnement des écosystèmes ainsi que les services écosystémiques, avec des conséquences économiques et sociales. Parmi les conséquences de ces introductions sont le déplacement d'espèces indigènes, des compétitions avec des espèces en danger et des effets sur les trajectoires éco-évolutives des espèces des communautés envahies. Bien que crucial pour anticiper le devenir des espèces non-indigènes, comprendre les mécanismes d'acclimatation et d'adaptation agissant post-introduction reste un challenge chez les algues. Au cours de cette thèse, nous avons étudié certains processus d'acclimatation, en particulier le rôle des bactéries associées, et leurs effets, en utilisant comme modèle d'étude Sargassum muticum. Cette algue brune originaire d'Asie, est une espèce emblématique parmi les algues introduites avec une présence du Mexique à l'Alaska en Amérique et du Maroc à la Norvège en Europe. Nous avons effectué une analyse bibliographique des traits et caractéristiques écologiques qui pourraient expliquer son succès. Nous avons ensuite montré que l'acidification n'a pas d'effets significatifs sur les bacteries associées, bien que des changements saisonniers du microbiome aient été observés. Enfin, nous avons utilisé un modèle de niche écologique, intégrant la phénologie, pour prédire la distribution de S. muticum sous deux scénarios de changement climatique. Selon nos résultats, d'ici 2100, la distribution de S. muticum devrait se déplacer vers le nord dans l'hémisphère nord avec des régressions dans certaines zones actuellement occupéesNon-indigenous seaweeds impact natural communities worldwide, affecting biodiversity, ecosystem functioning, and ecosystem services, resulting in significant economic and social consequences. Among major impacts are the displacement of native species, a threat to endangered species, and effects on ecological and evolutionary processes within the invaded communities. While critical to predict the fate of introduced species, understanding the mechanisms of acclimation and adaptation following introduction represents a great challenge in seaweeds. In this thesis, we investigated some acclimation processes, with an emphasis on the role of associated microbiota, and examined their effects with Sargassum muticum as a model species. This brown seaweed native to Asia, is an emblematic invader among seaweeds, with a distribution now ranging from Mexico to Alaska in America and from Morocco to Norway in Europe. We first reviewed the competitive advantages and traits that may contribute to its invasiveness. We then showed that acidification has no significant effects on associated bacteria, although seasonal changes in the microbiome have been observed. Finally, we applied ecological niche modelling, but innovatively accounting for phenology, to project the distribution of S. muticum under two future climate change scenarios. According to our projections, by 2100 the distribution of S. muticum is expected to shift northwards along its European, North American and Asian distributions with partial retreat from the currently occupied areas
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Hales, J. M. "Studies on the introduced brown alga Sargassum muticum (Yendo) Fensholt with particular reference to reproduction." Thesis, University of Portsmouth, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372820.
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Serebryakova, Alexandra. "Acclimation and adaptation of invasive seaweeds - a case study with the brown alga Sargassum muticum." Doctoral thesis, Paris 6, 2017. http://hdl.handle.net/10400.1/10824.
Full textAbstract:
Non-indigenous seaweeds impact natural communities worldwide, affecting biodiversity, ecosystem functioning, and ecosystem services, resulting in significant economic and social consequences. Among major impacts are the displacement of native species, a threat to endangered species, and effects on ecological and evolutionary processes within the invaded communities. While critical to predict the fate of introduced species, understanding the mechanisms of acclimation and adaptation following introduction represents a great challenge in seaweeds. In this thesis, we investigated some acclimation processes, with an emphasis on the role of associated microbiota, and examined their effects with Sargassum muticum as a model species. This brown seaweed native to Asia, is an emblematic invader among seaweeds, with a distribution now ranging from Mexico to Alaska in America and from Morocco to Norway in Europe. We first reviewed the competitive advantages and traits that may contribute to its invasiveness. In addition, we provided an overview of putative underlying mechanisms of acclimation and adaptation and highlighted their role in seaweed invasions. We then examined the effects of ocean acidification on the microbiome of S. muticum and revealed that it does not have significant effects on the seaweed-associated microbiota despite certain changes in the microbial community. We further investigated the seasonal changes in the seaweed-associated microbiota and revealed significant differences between seasons and geographic locations. Finally, we applied ecological niche modelling, but innovatively accounting for phenology, to project the distribution of S. muticum under two future climate change scenarios. According to our projections, by 2100 the distribution of S. muticum is expected to shift northwards along its European, North American and Asian distributions with a partial retreat from the currently occupied areas.As algas não indígenas afetam comunidades naturais em todo o mundo, afetando a biodiversidade, o funcionamento dos ecossistemas e os seus serviços, com consequências económicas e sociais significativas. Entre os principais impactos estão deslocamento de espécies nativas e espécies ameaçadas e efeitos sobre processos ecológicos e evolutivos nas comunidades invadidas. A compreensão dos mecanismos de aclimatação e adaptação após a introdução representa um grande desafio nas algas marinhas. Nesta tese investigamos alguns processos de aclimatação, com ênfase no papel dos microorganismos associados e examinamos os seus efeitos usando Sargassum muticum como espécie modelo. Esta alga marinha nativa da Ásia é uma importante invasora, com uma distribuição atual do México ao Alasca na América e de Marrocos à Noruega na Europa. Primeiro analisamos as vantagens e características competitivas que podem contribuir para sua invasibilidade. Além disso, fornecemos uma visão geral dos mecanismos de aclimatação e adaptação subjacentes e destacamos seu papel nas invasões de algas marinhas. Em seguida, examinamos os efeitos da acidificação dos oceanos no microbioma de S. muticum e revelamos que não tem efeitos significativos sobre a comunidade microbiana das algas marinhas apesar de causar algumas mudanças na comunidade. No estudo das mudanças sazonais na microbiota associada às algas marinhas revelamos diferenças significativas entre as estações e os locais geográficos. Finalmente, realizamos modelação de nicho ecológico de forma inovadora para a fenologia, para projetar a distribuição de S. muticum em dois cenários futuros de mudança climática. De acordo com nossas projeções, até 2100, a distribuição de S. muticum deverá expandir-se para norte ao longo das suas distribuições européia, norte-americana e asiática, com retração parcial das áreas atualmente ocupadas.
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Gylle, A. Maria. "Physiological adaptations in two ecotypes of Fucus vesiculosus and in Fucus radicans with focus on salinity." Doctoral thesis, Mittuniversitetet, Institutionen för naturvetenskap, teknik och matematik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-13308.
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The in origin intertidal marine brown alga Fucus vesiculosus L. grow permanently sublittoral in the brackish Bothnian Sea, side by side with the recently discovered F. radicans L. Bergström et L. Kautsky. Environmental conditions like salinity, light and temperature are clearly different between F. vesiculosus growth sites in the Bothnian Sea (4-5 practical salinity units, psu; part of the Baltic Sea) and the tidal Norwegian Sea (34-35 psu; part of the Atlantic Ocean). The general aims of this thesis were to compare physiological aspects between the marine ecotype and the brackish ecotype of F. vesiculosus as well as between the two Bothnian Sea species F. vesiculosus and F. radicans. The result in the study indicates a higher number of water soluble organic compounds in the marine ecotype of F. vesiculosus compared to the brackish ecotype. These compounds are suggested to be compatible solutes and be due to an intertidal and sublittoral adaptation, respectively; where the intertidal ecotype needs the compounds as a protection from oxygen radicals produced during high irradiation at low tide. The sublittoral ecotype might have lost the ability to synthesize these compound/compounds due to its habitat adaptation. The mannitol content is also higher in the marine ecotype compared to the brackish ecotype of F. vesiculosus and this is suggested to be due to both higher level of irradiance and higher salinity at the growth site. 77 K fluorescence emission spectra and immunoblotting of D1 and PsaA proteins indicate that both ecotypes of F. vesiculosus as well as F. radicans have an uneven ratio of photosystem II/photosystem I (PSII/PSI) with an overweight of PSI. The fluorescence emission spectrum of the Bothnian Sea ecotype of F. vesiculosus however, indicates a larger light-harvesting antenna of PSII compared to the marine ecotype of F. vesiculosus and F. radicans. Distinct differences in 77 K fluorescence emission spectra between the Bothnian Sea ecotype of F. vesiculosus and F. radicans confirm that this is a reliable method to use to separate these species. The marine ecotype of F. vesiculosus has a higher photosynthetic maximum (Pmax) compared to the brackish ecotype of F. vesiculosus and F. radicans whereas both the brackish species have similar Pmax. A reason for higher Pmax in the marine ecotype of F. vesiculosus compared to F. radicans is the greater relative amount of ribulose-1.5-bisphosphate carboxylase/oxygenase (Rubisco). The reason for higher Pmax in marine ecotype of F. vesiculosus compare to the brackish ecotype however is not due to the relative amount of Rubisco and further studies of the rate of CO2 fixation by Rubisco is recommended. Treatments of the brackish ecotype of F. vesiculosus in higher salinity than the Bothnian Sea natural water indicate that the most favourable salinity for high Pmax is 10 psu, followed by 20 psu. One part of the explanation to a high Pmax in 10 psu is a greater relative amount of PsaA protein in algae treated in 10 psu. The reason for greater amount of PsaA might be that the algae need to produce more ATP, and are able to have a higher flow of cyclic electron transport around PSI to serve a higher rate of CO2 fixation by Rubisco. However, studies of the rate of CO2 fixation by Rubisco in algae treated in similar salinities as in present study are recommended to confirm this theory.Fucus vesiculosus L. (Blåstång) är en brunalg som i huvudsak växer i tidvattenzonen i marint vatten men arten klarar också att växa konstant under ytan i det bräckta Bottenhavet. Norska havet och den del av Bottenhavet, där algerna är insamlade i denna studie, har salthalterna 34-35 psu (praktisk salthaltsenhet) respektive 4-5 psu. F. radicans L. Bergström et L. Kautsky (Smaltång) är en nyligen upptäckt art (2005) som har utvecklats i Bottenhavet. F. radicans och Bottenhavets ekotyp av F. vesiculosus växer sida vid sida och har tidigare ansetts vara samma art. Sett till hela Östersjön, så ändras ytans salthalt från 25 till 1-2 psu mellan Östersjöns gräns mot Kattegatt och norra Bottenviken. Den låga salthalten i Östersjön beror på det höga flödet av sötvatten från älvarna och på ett litet inflödet av saltvatten i inloppet vid Kattegatt. Salthaltsgradienten är korrelerad med antalet arter som minskar med minskad salthalt. Östersjön är ett artfattigt hav och de arter som finns är till stor del en blandning av söt- och saltvattenarter. Det finns bara ett fåtal arter som är helt anpassade till bräckt vatten och F. radicans är en av dem. Exempel på miljöskillnader för F. vesiculosus i Norska havet och i Bottenhavet är salthalten, tidvattnet, ljuset och temperaturen. Tidvattnet i Norska havet gör att algerna växlar mellan att vara i vattnet och på land, vilket utsätter algerna för stora ljusskillnader, snabba och stora temperaturväxlingar samt även torka. De alger som växer i Bottenhavet har däremot en jämnare och lägre temperatur, istäcke på vintern och mindre tillgång på ljus eftersom de alltid lever under vattenytan. Skillnaderna i miljön mellan växtplatserna leder till skillnader i fysiologiska anpassningar. Anledningen till att F. vesiculosus och F. radicans valdes som studieobjekt i denna avhandling är att de är viktiga nyckelarter i Bottenhavet. F. vesiculosus och F. radicans är de enda större bältesbildande alger som finns i det artfattiga ekosystemet och de används därför flitigt som mat, gömställe, parningsplats och barnkammare för t.ex. fisk. Att de är nyckelarter gör det angeläget att försöka förstå hur algerna är anpassade och hur de reagerar på miljöförändringar för att få veta hur de kan skyddas och bevaras. F. radicans inkluderades även för att se hur en naturlig art i Bottenhavet är anpassad i jämförelse med den invandrade F. vesiculosus. Marin F. vesiculosus inkluderades för att vara en artreferens från artens naturliga växtplats. Studien visar att det finns fler vattenlösliga organiska substanser (finns vissa organiska substanser som har en proteinskyddande funktion) i den marina ekotypen av of F. vesiculosus än i Bottenhavets ekotyp. Anledningen till detta föreslås vara en anpassning till att växa i tidvattenzonen. Vid lågvatten utsätts F. vesiculosus från Norska havet för starkt ljus, uttorkning, och snabba temperatur- växlingar vilket gör att den kan behöva dessa organiska substanser som skydd mot fria syreradikaler som bildas under lågvattenexponeringarna. F. vesiculosus från Bottenhavet har troligen mist förmågan att syntetisera dessa substanser på grund av anpassning till att hela tiden växa under ytan. Mängden mannitol (socker) är högre i den marina ekotypen av of F. vesiculosus än i Bottenhavets ekotyp. Detta föreslås bero på högre fotosyntetiskt maximum i F. vesiculosus från Norska havet jämfört med ekotypen från Bottenhavet. Skillnaden i fotssyntetiskt maximum är bland annat kopplat till ljus- och salthaltskillnaden på algernas växtplatser. Denna teori styrks av att både fotosyntesen och halten av mannitol ökar i Bottenhavets ekotyp när den behandlas i högre salthalt. Studien visar även att båda ekotyperna av F. vesiculosus samt F. radicans har ett ojämnt förhållande mellan fotosystem II och I (PSII och PSI) med en dominans av PSI. Denna slutsats är baserad på fluorescens emissions mätningar vid 77 K (-196 °C) och mätning av den relativa mängden D1 protein (motsvarar PSII) och PsaA protein (motsvarar PSI). F. vesiculosus från Bottenhavet visar ett emission spektrum som pekar mot en jämnare fördelning av PSII och PSI jämfört med den marina ekotypen och F. radicans. Detta stämmer dock inte med förhållandet mellan D1/PsaA som indikerar att alla tre har mer PSI än PSII. Förklaringen till avvikelsen mellan metoderna antas vara att F. vesiculosus från Bottenhavet har större ljus-infångande antennpigment än marin F. vesiculosus och F. radicans. De tydliga skillnaderna i 77 K fluorescens emission spektra mellan Bottenhavets F. vesiculosus och F. radicans visar att denna metod kan användas som säker artidentifiering. Den marina ekotypen av F. vesiculosus har högre fotosyntetiskt maximum än de båda arterna från Bottenhavet. Mätningar av den relativa mängden av enzymet Rubisco, viktigt för upptaget av koldioxid hos växter och alger, visar att mängden enzym är en sannolik förklaring till skillnaden i fotosyntetiskt maximum mellan den marina ekotypen av F. vesiculosus och F. radicans och detta är troligen en normal artskillnad. Mängden Rubisco kan dock inte förklara skillnaden i fotosyntetiskt maximum mellan de båda ekotyperna av F. vesiculosus. För att undersöka vad skillnaden mellan dessa två beror på så föreslås istället mätningar av Rubisco’s koldioxidfixeringshastighet. Det är en ökning av fotosyntetiskt maximum i Bottenhavets ekotyp av F. vesiculosus när den behandlas i högre salthalt (10, 20 och 35 psu) och det högsta fotosyntetiska maximumet uppmättes i alger som behandlats i 10 psu. Denna ökning beror inte på ökning i den relativa mängden av Rubisco. Ökningen i fotosyntesen speglas dock av en ökning av den relativa mängden PsaA. Detta antas bero på att det behövs mer energi i form av ATP och att en ökning av detta kan ske på grund av att mer PsaA kan driva den cykliska elektrontransporten i fotosyntesreaktionen. Ökat behov av ATP antas bero på en ökning av Rubisco aktiviteten men mätning av aktiviteten krävs för att bekräfta detta.
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Rui, Fabio [Verfasser], Wilhelm [Gutachter] Boland, and Rainer [Gutachter] Beckert. "Biosynthesis of C11 hydrocarbons in the brown alga : Ectocarpus siliculosus / Fabio Rui ; Gutachter: Wilhelm Boland, Rainer Beckert." Jena : Friedrich-Schiller-Universität Jena, 2009. http://d-nb.info/1178249182/34.
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Cormier, Alexandre. "Le modèle algue brune pour l'analyse fonctionnelle et évolutive du déterminisme sexuel." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066646/document.
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Les mécanismes de détermination génétique du sexe, qui requièrent la présence de régions chromosomiques non recombinantes ou bien de chromosomes sexuels, ont émergé de manière indépendante et répétée au sein de plusieurs lignées d'eucaryotes. La plupart des connaissances acquises dans ce domaine portent sur un nombre limité de groupes d'eucaryotes. La disponibilité d'une espèce modèle pour le groupe des algues brunes, Ectocarpus siliculosus, dont le génome a été séquencé, permet de disposer des outils nécessaires pour étudier ces mécanismes au sein d'une lignée phylogénétiquement éloignée des modèles classiquement étudiés. L'un des premiers défis a été d'identifier les chromosomes sexuels dans le génome d'E. siliculosus et de réaliser l'analyse comparative de ces structures. Par la suite, l'analyse de l'expression des gènes entre individus mâles et femelles à différents stades du cycle de vie a permis d'identifier les gènes différentiellement exprimés, de caractériser leurs fonctions et d'analyser leur évolution moléculaire. Les nombreuses données générées afin de réaliser ces différentes analyses ont permis de proposer une nouvelle version de l'assemblage du génome et de l'annotation structurale et fonctionnelle de l'ensemble des gènes codants et non-codants d'E. siliculosus. Ces différents travaux ont permis d'apporter une importante contribution sur les connaissances dans le domaine de l'analyse fonctionnelle et évolutive du déterminisme sexuel chez les algues brunes ainsi qu'une importante actualisation des ressources génomiques du modèle EctocarpusGenetically determined sex determination mechanisms, which are controlled by non-recombinant chromosome regions or sex chromosomes, have emerged independently and repeatedly across several eukaryotic lineages. Most of the knowledge acquired in this area has been obtained for a limited number of eukaryotic groups. The availability of a model organism for the brown algae, Ectocarpus, whose genome has been sequenced, allows the development of tools to study these mechanisms in a lineage that is phylogenetically distant from classically studied models. One of the first challenges was to identify the sex chromosomes in Ectocarpus and to carry out a comparative analysis of these genomic structures. Analysis of gene expression in males and females at different stages of the life cycle then allowed the identification of differentially expressed genes. The functions and molecular evolution of these sex-biased genes was then studied. The large amount of data generated during the course of these analyses allowed the establishment of a new version of the genome assembly and refined structural and functional annotation of both coding and non-coding genes in Ectocarpus. This work helped made a significant contribution to knowledge in the field of functional and evolutionary analysis of sex determination in brown algae and a significantly updated the genomic resources available for the model organism Ectocarpus
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Sousa, Alessandra de Paula Alves. "Antitumor potential of alginates isolated from the seaweed brown sargassum vulgare c. agardh (1820)." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8.
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FundaÃÃo de Amparo à Pesquisa do Estado do CearÃAlginates are natural polysaccharides composed of linear polymers of 1-4 linked beta-D- mannuronic and alfa-L-guluronic acid residues in widely varying composition and sequential arrangements. The purpose of this study was to evaluate the anti cancer potential of two alginates âV (low viscosity) and +V (high viscosity), isolated from the seaweed Sargassum vulgare. Alginates were tested for cytotoxicity using the brine shrimp lethality assay, sea urchin development assay, hemolysis assay and MTT assay using HL-60, MCF-7, CEM, HCT-8 and B16 tumor cell lines. None of the compounds tested showed in vitro toxicity. On the other hand, alginates showed antitumor activity in vivo against Sarcoma 180 cells transplanted in mice. Both alginates inhibited the growth of solid tumor in mice implanted with 5 x 105 tumor cells after both oral and intraperitoneal administration at 50 and 100 mg/m2, as well as 25 mg/m2 after oral administration. Alginate +V presented higher inhibition effects after oral administration. The association of alginate +V (25 mg/m2) with 5-FU (15 mg/m2) showed an increasing activity against tumor compared to +V individually. Alginates antitumor activity at 50 and 100 mg/m2 was related to the tumor proliferation rate inhibition, as observed by reduction of Ki-67 staining in tumor of the treated-animals. The histopathological analysis revealed that both alginates administrated at 50 and 100 mg/m2 presented hepatotoxicity and nefrotoxicity, being -V was more toxic than +V. The kidney perfusion assay demonstrated that âV was more toxic than +V, corroborating date from histopathological analysis. The histopathological analysis of spleen showed that both alginates cause the enlargement of the white pulp of treated animals, suggesting that the observed antitumor activity could be related to alginates immunomodulatory properties. In fact, the alginates treatment (25 mg/m2) prevents the reduction number of leukocytes and lymphocytes, induced by 5-FU treatment as observed from the hematological analysis.
Alginato à um biopolÃmero natural, constituÃdo por ligaÃÃes lineares (1-4) de β-D-Ãcido manurÃnico e α-L-Ãcido gulurÃnico arranjados em seqÃÃncias e proporÃÃes nÃo regulares ao longo da cadeia. Este trabalho visou estudar o potencial antitumoral de dois alginatos com diferentes viscosidades isolados da alga marinha Sargassum vulgare, denominados de âV (menos viscoso) e +V (mais viscoso). Os ensaios atividade antimitÃtica no desenvolvimento do ouriÃo-do-mar, atividade antiproliferativa nas linhagens tumorais HCT-8, MCF-7, HL-60, CEM e B-16, atividade hemolÃtica e toxicidade em Artemia sp, mostraram que ambos os alginatos nÃo possuem toxicidade in vitro. No entanto, os alginatos âV e +V apresentaram atividade antitumoral in vivo no modelo experimental do Sarcoma 180. Ambos os alginatos administrados por via oral e intraperitoneal nas concentraÃÃes de 50 e 100 mg/m2, bem como na concentraÃÃo de 25 mg/m2 por via oral inibiram o crescimento do tumor sÃlido em camundongos transplantados com 5 x 105 cÃlulas tumorais. O alginato +V administrado por via oral apresentou um maior efeito inibitÃrio. O tratamento do alginato +V por via oral (25 mg/m2) associado ao 5-FU (15 mg/m2) promoveu um aumento da resposta contra o tumor quando comparado ao tratamento com o alginato +V isoladamente. A inibiÃÃo da proliferaÃÃo das cÃlulas tumorais, determinada por imunohistoquÃmica com o Ki-67, foi observada em ambos os tratamentos por via oral e intraperitoneal com os alginatos âV e +V nas concentraÃÃes de 50 e 100 mg/m2. As anÃlises histopatolÃgicas revelaram que os alginatos âV e +V administrados nas concentraÃÃes de 50 e 100 mg/m2 por via oral e intraperitoneal possuem toxicidade hepÃtica e renal, no entanto, o alginato âV apresentou maior toxicidade que o alginato +V. O estudo da nefrotoxicidade avaliada no sistema de perfusÃo renal demonstrou que o alginato âV tambÃm apresenta um maior efeito que o alginato +V. A anÃlise histopatÃlogica do baÃo revelou que ambos os alginatos levam a uma hiperplasia da polpa branca nos animais tratados, o que sugere que a atividade antitumoral esteja relacionada Ãs propriedades imunomoduladoras desses compostos. De acordo com a anÃlise hematolÃgica, os animais tratados com o 5-Fu (15 mg/m2) apresentaram leucopenia e linfocitopenia, sendo este quadro revertido com o tratamento associado com os alginatos âV e +V (25 mg/m2).
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Montecinos, Alejandro. "Species delienation and hybridization in the brown seaweed Ectocarpus complex." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066328/document.
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Le genre Ectocarpus Lyngbye (Ectocarpales, Phaeophyceae) regroupe des algues marines filamenteuses caractérisées par un cycle haploïde-diploïde. L'objectif de la thèse était de délimiter les espèces et d'étudier la spéciation dans ce genre. Nous avons commencé par clarifier le nombre d'espèces cryptiques en utilisant deux loci indépendants et une approche intégrative associant une analyse de détection de " barcode gap " avec des reconstructions phylogénétiques. Nos résultats montrent l'existence d'au moins 15 espèces qui se répartissent en un groupe monophylétique composé d'E. crouaniorum (Ecro) et de deux espèces proches ainsi que d'un mélange paraphylétique composé des 12 autres espèces incluant E. siliculosus (Esil). Deuxièmement, les analyses de séquençage Rad et de phylogénomique ont permis de résoudre les relations au sein du groupe paraphylétique. Les espèces se regroupent maintenant en deux clades divergents (Ecro and Esil). Des niveaux de divergence variables entre espèces sont révélés au sein du clade Esil. Des phénomènes d'hybridation entre les espèces les plus apparentées, et trouvées en sympatrie, sont suspectés. Finalement, l'importance de l'isolement reproducteur a été étudié entre les espèces Esil et Ecro, les plus communes, mais les plus divergentes, en utilisant des marqueurs spécifiques de chacune des espèces. Nos résultats indiquent que la méiose agit comme une forte barrière reproductive entre ces espèces et démontrent que les espèces du genre Ectocarpus sont d'excellents systèmes pour étudier les conséquences évolutives de l'hybridation et de l'introgression pour le maintien ou la divergence des espèces grâce à leur cycle haploïde-diploïdeThe genus Ectocarpus Lyngbye (Ectocarpales, Phaeophyceae) comprises marine filamentous algae characterized by an alternation between two independent multicellular organisms of different ploidy. The general objective of the thesis was to study species delineation and speciation within this genus. We started clarifying the number of cryptic species using two unlinked loci (COI-5P and ITS1) and an integrative approach associating barcode gap detection analyses with phylogenetic reconstructions. We showed the presence of at least 15 species partitioned within a monophyletic group composed of E. crouaniorum (Ecro) and two closely related species and a paraphyletic assemblage composed of the remaining 12 other species including E. siliculosus (Esil). Second, Rad sequencing and phylogenomics analyses allowed to resolve the relationships within the paraphyletic assemblage. The different species becomes well separated into two divergent clades (Ecro and Esil). A diversity of taxa with various levels of divergence was revealed within the clade Esil and hybridization between the closest and sympatric species was suggested. Finally, the importance of reproductive isolation among the two commonest but most divergent species Esil and Ecro was studied using species-specific nuclear and cytoplasmic markers jointly with 9 microsatellites. We showed that meiosis acts as a strong reproductive barrier among these two species and demonstrates that the species of the genus Ectocarpus are excellent systems to study evolutionary consequences of hybridization and introgression for the maintenance or breakdown of species because of their haploid diploid life cycle
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Dore, Celina Maria Pinto Guerra. "Aspectos estruturais, farmacol?gicos e biol?gicos de fucanas da alga marrom sargassum vulgare." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12570.
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Previous issue date: 2012-10-15Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
The present study examines the chemical composition and their effects on free radicals, inflammation, angiogenesis, coagulation, VEGF effects and cellular proliferation of a polysaccharides from alga Sargassum vulgare. The sulfated polysaccharide was extracted from brown seaweed by proteolysis with enzymes maxataze. The presence of proteins and sugars were observed in crude polysaccharides. Fractionation of this crude extract was made with growing concentration of acetone (0.3-1.5 v) and produced four groups of polysaccharides. Anionic polysaccharides from brown seaweed Sargassum vulgare, SV1and PSV1 were fractionated (SV1) and purified (PSV1), and displayed with high total sugars and sulfate content and very low level of protein. This fucan SV1 contains low levels of protein and high carbohydrate and sulfate content. This polysaccharides prolonged activated partial thromboplastin time (aPTT) at 50 μg (>240 s). SV1 was found to have no effect on prothrombin time (PT), corresponding to the extrinsic pathway of coagulation. SV1 exhibits high antithrombotic action in vivo, with a concentration ten times higher than heparin. Polysaccharides from S. vulgare promoted direct inhibition enzymatic activity of thrombin and stimulated enzymatic activity of FXa. SV1 showed optimal inhibitory activity of thrombin (50.2?0.28%) at a concentration of 25 μg/mL. Its antioxidant action on scavenging radicals by DPPH was (22%), indicating the polymer has no cytotoxic action (hemolytic) on ABO and Rh blood types in different erythrocyte groups and displays strong anti-inflammatory action on all concentrations tested in the carrageenan-induced paw edema model, demonstrated by reduced edema and cellular infiltration. Angiogenesis is a dynamic process of proliferation and differentiation. It requires endothelial proliferation, migration, and tube formation. In this context, endothelial cells are a preferred target for several studies and therapies. The antiangiogenic efficacy of polysaccharides was examined in vivo in the chick chorioallantoic membrane (CAM) model by using fertilized eggs. Decreases in the density of the capillaries were assessed and scored. The results showed that SV1 and PSV1 have an inhibitory effect on angiogenesis. These results were also confirmed by inhibition tubulogenesis in rabbit aorta endothelial cell (RAEC) in matrigel. These compounds were assessed in Apoptosis assay (Annexin V - FITC / PI) and cell viability by MTT assay of RAEC. These polysaccharides do not affect the viability and do not have apoptotic or necrotic action. RAEC cell when incubated with SV1 and PSV1showed inhibition of VEGF secretion, observed when compounds were incubated at 25, 50 and 100 μg/μL. The VEGF secretion with the RAEC cell line for 24 h, was more effective for PSV1 at 50 μg/μL(71.4%) than SV1 100 μg/μL (75.9%). SV1 and PSV1 had an antiproliferative action (47%) against tumor cell line HeLa. Our results indicate that these sulfated polysaccharides have antiangiogenic and antitumoral actions
O presente estudo analisa a composi??o qu?mica e seus efeitos sobre os radicais livres, inflama??o, angiog?nese, coagula??o, VEGF e prolifera??o celular dos polissacar?deos de uma alga Sargassum vulgare. O polissac?rido sulfatado foi extra?do a partir de algas marrons por prote?lise com a enzima maxataze. A presen?a de prote?nas e a??cares foram observados no cru de polissacarideos. Fracionamento do o extrato bruto foi feito com concentra??es crescente de acetona (0,3-1,5 v), produzindo quatro grupos de polissacarideos. Estes compostos ani?nicos da alga S. vulgare, foram fracionados (SV1) e purificados (PSV1) exibindo com alta a??cares totais e sulfatecontent e n?vel muito baixo de prote?nas.A fucana SV1 cont?m baixos n?veis de prote?na e de hidratos de carbono e alto teor de sulfato. Este polissacar?deos prolongou o tempo de tromboplastina parcial activada (aPTT) a 50 ug (>240 s). n?o foi observado qualquer efeito de SV1 sobre o tempo de protrombina (PT), que corresponde a via extr?nseca da coagula??o. SV1 exibiu alta a??o antitromb?tica in vivo, com uma concentra??o 10 vezes maior do que a heparina. SV1 promoveu a actividade de inibi??o enzim?tica direta da trombina e estimulou a atividade enzim?tica do FXa. Mostrou tamb?m, atividade inibidora optima de trombina (50,2 ? 0,28%) a uma concentra??o de 25 ug / mL. A sua ac??o anti-oxidante de radicais scavenging por DPPH foi de (22%), indicando que o pol?mero n?o tem qualquer a??o citot?xica (hemol?tica) em tipos de sangue ABO e Rh, em diferentes grupos de eritr?citos e exibindo alta a??o anti-inflamat?ria em edema de pata de ratos Wistar em todas as concentra??es testadas induzida por carragenina. Tal processo foi demonstrado por edema e infiltra??o celular. A angiogenese ? um processo din?mico de prolifera??o e diferencia??o. Ele requer prolifera??o endotelial, migra??o, e a forma??o do tubo. Neste contexto, as c?lulas endoteliais s?o um alvo preferido para muitos estudos e terapias. A efic?cia antiangiogenico de polissacar?deos foi examinada in vivo na membrana corioalant?ica pinto (CAM) usando-se ovos fertilizados. Diminui??es na densidade dos capilares foram avaliados e pontuados. Os resultados mostraram que SV1 e PSV1 tem um efeito inibidor da angiogenese. Estes resultados foram tamb?m confirmados por tubulogenesis inibi??o na c?lula endotelial da aorta de coelho (RAEC) em matrigel. C?lulas RAEC quando foram incubadas com SV1and PSV1 demonstraram inibi??o da secre??o de VEGF, a 25, 50 e 100 ug/mL. A secre??o de VEGF com a linha de c?lulas RAEC durante 24 h, foi mais eficaz para PSV1 a 50 ug / mL (71,4%) do que SV1 100 ug / mL (75,9%). SV1 e PSV1 posuiram uma ac??o antiproliferativa (47%) contra as c?lulas tumorais tipo HeLa. Estes compostos foram avaliados tamb?m, no ensaio de apoptose (anexina V - FITC / PI) e a viabilidade celular pelo ensaio de MTT de RAEC. Estes polissacar?deos n?o afetaram a viabilidade e n?o tiveram a??o apopt?tica ou necr?tica. Nossos resultados indicam que estes polissacar?deos sulfatados t?m a??es antiangiog?nica e antitumoral e constituem um importante alvo biol?gico e farmacol?gico
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Cormier, Alexandre. "Le modèle algue brune pour l'analyse fonctionnelle et évolutive du déterminisme sexuel." Electronic Thesis or Diss., Paris 6, 2015. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2015PA066646.pdf.
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Les mécanismes de détermination génétique du sexe, qui requièrent la présence de régions chromosomiques non recombinantes ou bien de chromosomes sexuels, ont émergé de manière indépendante et répétée au sein de plusieurs lignées d'eucaryotes. La plupart des connaissances acquises dans ce domaine portent sur un nombre limité de groupes d'eucaryotes. La disponibilité d'une espèce modèle pour le groupe des algues brunes, Ectocarpus siliculosus, dont le génome a été séquencé, permet de disposer des outils nécessaires pour étudier ces mécanismes au sein d'une lignée phylogénétiquement éloignée des modèles classiquement étudiés. L'un des premiers défis a été d'identifier les chromosomes sexuels dans le génome d'E. siliculosus et de réaliser l'analyse comparative de ces structures. Par la suite, l'analyse de l'expression des gènes entre individus mâles et femelles à différents stades du cycle de vie a permis d'identifier les gènes différentiellement exprimés, de caractériser leurs fonctions et d'analyser leur évolution moléculaire. Les nombreuses données générées afin de réaliser ces différentes analyses ont permis de proposer une nouvelle version de l'assemblage du génome et de l'annotation structurale et fonctionnelle de l'ensemble des gènes codants et non-codants d'E. siliculosus. Ces différents travaux ont permis d'apporter une importante contribution sur les connaissances dans le domaine de l'analyse fonctionnelle et évolutive du déterminisme sexuel chez les algues brunes ainsi qu'une importante actualisation des ressources génomiques du modèle EctocarpusGenetically determined sex determination mechanisms, which are controlled by non-recombinant chromosome regions or sex chromosomes, have emerged independently and repeatedly across several eukaryotic lineages. Most of the knowledge acquired in this area has been obtained for a limited number of eukaryotic groups. The availability of a model organism for the brown algae, Ectocarpus, whose genome has been sequenced, allows the development of tools to study these mechanisms in a lineage that is phylogenetically distant from classically studied models. One of the first challenges was to identify the sex chromosomes in Ectocarpus and to carry out a comparative analysis of these genomic structures. Analysis of gene expression in males and females at different stages of the life cycle then allowed the identification of differentially expressed genes. The functions and molecular evolution of these sex-biased genes was then studied. The large amount of data generated during the course of these analyses allowed the establishment of a new version of the genome assembly and refined structural and functional annotation of both coding and non-coding genes in Ectocarpus. This work helped made a significant contribution to knowledge in the field of functional and evolutionary analysis of sex determination in brown algae and a significantly updated the genomic resources available for the model organism Ectocarpus