Academic literature on the topic 'Phaeophycae'

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.

Etude des peuplements le long des côtes et estimation de la biomasse exploitable. Etude au laboratoire de l'influence des principaux facteurs du milieu sur la croissance et du développement de l'algue. Morphogénèse des boutures, capacité de régénération. Valorisation par mise au point à une technique d'obtention d'un extrait liquide dont on étudie l'activité sur des plantes horticoles

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.

Les Phaeophyceae ont acquis la multicellularité indépendamment des autres lignées multicellulaires, elles offrent donc la possibilité d’étudier des mécanismes de développement nouveaux et originaux. Ectocarpus siliculosus est l’espèce modèle pour les algues brunes, et les étapes de développement du sporophyte ont été décrites précisément. Pour comprendre leurs bases génétiques et moléculaires, une approche de génétique directe a été adoptée. Le mutant étoile est le premier mutant de morphogenèse décrit de manière exhaustive, sa mutation, simple locus et récessive, découple le tempo et la position de ramification en raison d’un défaut de différenciation cellulaire qui conduit à la sur-ramification. Le rhizoïde du gamétophyte est lui aussi affecté, il rappelle le phénotype du sporophyte. Les deux phénotypes semblent génétiquement liés, et il est probable qu’ils soient dus à la mutation etl. Le locus ETL a été identifié par une approche de clonage positionnel. Le génome du mutant étoile a été séquencé (illumina) ce qui a permis par comparaison avec le génome du sauvage de prédire les mutations candidates dans le locus ETL. La seule mutation non-silencieuse affecte une protéine avec deux domaines fonctionnels : un domaine BAR/IMD et un domaine RhoGAP. Les domaines BAR sont impliqués dans la reconnaissance des membranes et sont capables d’inhiber les domaines RhoGAP qui sont des régulateurs des RhoGTPases. Ce gène s’exprimant dans les cellules apicales du filament de l’algue, il pourrait maintenir la croissance apicale polarisée par l’interaction, aux apex, entre ses deux domaines protéique. Le gène ETL est le premier gène de morphogenèse cloné chez E. Siliculosus, il ouvre d’immenses perspectives en terme de caractérisation fonctionnelle et d’approches « evo-devo »<br>Multicellularity has occurred independently in Phaeophyceae and in other multicellular lineages. Therefore these organisms offer the opportunity to study novel and alternative developmental processes. Ectocarpus siliculosus is the model species for brown algae and the development of its early sporophyte has been described precisely. To understand the genetic and molecular basis of this development, a forward genetic approach has been carried out. The mutant étoile is the first morphogenetics mutant exhaustively described. Its single locus and recessive mutation, leads to a defect in cell differentiation that decouples branching tempo and position leading to a hyperbranched phenotype. Gametophyte rhizoïde is modifoed as well, it resembles the étoile early sporophyt phenotype. The two phenotypes are genetically linked and thought to be induced by the etl mutation. The ETL locus has been identified by a map-based approach. The illumina sequencing of the mutant genome allowed to propose candidate mutations. The only non-silent mutation affects a protein with two functional domains: a BAR/IMD domain and RhoGAP domain. BAR/IMD domains can recognize lipid membranes and are able to inhibit RhoGAP domains which are regulators for RhoGTPases. As ETL is expressed in the filamentous apical cells, it could maintain tip-growth in the apices through interaction between its two domains. ETL gene is the first morphogenetic gene that has been cloned, and hence it opens hudge perspectives for functional characterization and evo-devo studies

Mestrado em Toxicologia<br>O género Fucus apresenta vasta distribuição na zona costeira Ibérica, tendo sido descritas cinco espécies para Espanha e quatro para Portugal (Fucus spiralis L., F. vesiculosus L., F. ceranoides L. e F. serratus L.). Possui enorme importância, tanto ecológica como comercial, essencialmente na produção de produtosnaturais medicinais. As espécies deste género surgem em diversos locais, incluindo os expostos a descargas de efluentes urbanos, industriais e aos lixíviados de terrenos agrícolas, encontrando-se normalmente nas zonas rochosas, onde sofrem zonação notória, que é controlada por complexas interacções fisiológicas e biológicas. O objectivo principal deste trabalho consistiu em efectuar os estudos de base necessários à utilização de espécies do género Fucus como bioindicadores em programas de biomonitorização em zonas costeiras e estuarinas da costa Noroeste de Portugal. Para atingir este objectivo foram desenvolvidos três trabalhos específicos: 1) analisar a variação morfológica de três espécies de Fucus (F. ceranoides, F. spiralis e F. vesiculosus), recolhidos na costa Noroeste Atlântica de Portugal entre o estuário do rio Minho e a Ria de Aveiro durante um ano, e o estabelecimento de correlações com os parâmetros ambientais; 2) avaliar o potencial de bioacumulação de mercúrio das espécies de Fucus [F. ceranoides, F. spiralis (F. spiralis var. platycarpus e F. spiralis var. spiralis) e F. vesiculosus]; 3) desenvolver e validar a metodologia necessária à utilização da actividade de glutationa S-transferase (GST) de Fucus spp. como biomarcador de contaminação ambiental. Através da Análise Canónica de correspondência foi possível perceber que o factor ambiental preponderante na variação dos parâmetros morfométricos parece ser a temperatura, estando este intimamente relacionado com o pH e a salinidade, em todas as espécies analisadas. A quantificação de mercúrio em três partes estruturais (receptáculos, lâmina e base) das espécies de Fucus, permitiu observar que os receptáculos continham menor concentração do que a base e a lâmina. Os valores obtidos para o sedimento apresentaram-se concordantes com os obtidos no material biológico (apesar dos espécimes consistentemente registarem concentrações superiores). Estes resultados sugerem que as espécies e variedades de Fucus estudadas são boas bioindicadores da contaminaçãopor mercúrio, em ecossistemas marinhos e estuarinos. F. ceranoides, F. spiralis var. platycarpus e F. vesiculosus apresentaram os valores mais baixos da actividade da GST nos locais de referência. As estações de amostragem, localizadas em áreas com reconhecida contaminação por hidrocarbonetos aromáticos policíclicos (HAPs), apresentaram valores mais elevados de actividade de GST, sugerindo indução dos mecanismos de destoxificação. Este facto não foi, no entanto, observado em F. spiralis var. spiralis.<br>The genus Fucusexhibits a wide distribution on the Iberian coast. Five species have been described for Spain and four for Portugal (Fucus spiralis L., F. vesiculosus L., F. ceranoides L. and F. serratus L.). This genus is of enormous importance, both from ecological and commercial (essentially in the production of natural medicinal products) points of view. Fucus spp. exists in several sites, including those receiving urban and industrial effluent discharges and leachates from farmland. The species of the Fucus genus are mainly found in rocky areas, where conspicuous zonation occurs, which is controlled by complex physiological and biological interactions. The main aim of this study was to launch the necessary basis to validate the use of the Fucusspecies as bioindicators in coastal and estuarine environments. To achieve this objective three steps with specific objectives were outlined: 1) analysis of morphologic variation in three species of Fucus (F. ceranoides, F. spiralis and F. vesiculosus), collected during a year, from the Portuguese Northwestern Atlantic coast (between the estuary of Minho river and the Aveiro tidal lagoon), and the establishment of correlations with environmental parameters; 2) evaluation of the potential of Fucus [F. ceranoides, F. spiralis (F. spiralis var. platycarpus and F. spiralis var. spiralis) and F. vesiculosus] to bioacumulate mercury; 3) to develop and validate the necessary methodologies for the application of Fucus spp. glutatione S-transferase as a biomarker of environmental contamination. Canonical correspondence analysis indicates that the dominant factor influencing morphometric parameters is temperature, always in close correlation with pH and salinity. Quantification of mercury in the three structural parts considered (receptacles, stipe and holdfast) showed that the receptacles consistently showed the lowest concentrations throughout the entire sampling campaign. Values obtained for the sediment were always consistent with the ones obtained for specimens, (the latter always presented higher concentrations). This leads to the conclusion that Fucuscan be considered a good bioindicator for mercury contamination in coastal and estuarine environments. As expected, F. ceranoides, F. spiralis var. platycarpus and F. vesiculosus registered the lowest values of GST activity in the reference stations. Sampling stations located in areas were contamination by polycyclic aromatic hydrocarbons (PAHs) is well known, showed higher values of activity for this enzyme, suggesting that detoxification mechanisms were induced.However, a different pattern was observed for F. spiralis var. spiralis.

As algas pardas filamentosas (Phaeophyceae) constituem um grupo essencialmente marinho com morfologia extremamente simples. A identificação taxonômica dessas algas é bastante difícil quando empregados apenas caracteres morfológicos devido à grande plasticidade fenotípica que apresentam. No Brasil, nenhum estudo sistemático foi feito com seus representantes empregando-se dados moleculares. Neste contexto, a diversidade de algas pardas filamentosas dos gêneros Acinetospora, Asteronema, Bachelotia, Ectocarpus, Hincksia e Feldmannia foi investigada pela primeira vez no Brasil sob uma abordagem molecular, complementada com dados morfológicos. As coletas abrangeram a região sudeste do Brasil, incluindo a área de ressurgência dos litorais do Rio de Janeiro e Espírito Santo, que abriga quase que a totalidade de táxons de algas pardas filamentosas citadas para o país. Foi utilizado o marcador mitocondrial do tipo DNA Barcode, COI-5P e o marcador plastidial para inferências filogenéticas, o rbcL. Os estudos moleculares e morfológicos permitiram identificar 10 táxons para o litoral sudeste brasileiro: oito da ordem Ectocarpales: Acinetospora filamentosa, \"Feldmannia\" irregulares, \"Feldmannia irregulares\" 1, \"Feldmannia irregulares\" 2, \"Feldmannia\" mitchelliae, \"Hincksia\" conífera e Hincksia sandriana (família Acinetosporaceae) e Ectocarpus fasciculatus (família Ectocarpaceae) e dois da ordem Scytothamnales: \"Asteronema\" breviarticulatum (família Asteronemataceae) e Bachelotia antillarum (família Bachelotiaceae). A família Acinetosporaceae não é monofilética e se dividiu em dois agrupamentos, Acinetosporaceae 1, que incluiu a maioria dos representantes brasileiros e a espécie tipo da família, Acinetospora crinita, e para o qual o nome da família deve ser retido; e Acinetosporaceae 2, que incluiu os autênticos gêneros Feldmannia, Hincksia e Pylaiella com suas respectivas espécies-tipo, Feldmannia lebelli, Hincksia hincksiae e Pylaiella litorallis, respectivamente, e para o qual, uma nova família deverá ser proposta. Hincksia sandriana foi a única espécie estudada que se agrupou no clado do autêntico gênero Hincksia e é citada pela primeira vez para o Brasil, constituindo um caso de introdução recente. Para os demais representantes agrupados em Acinetosporaceae 1, excluindo Acinetospora, um novo gênero para a ciência deverá ser proposto. Os táxons \"H.\" conífera, \"F.\" irregulares, \"F. irregulares\" 1, \"F. irregulares\" 2 e \"F.\" mitchelliae não pertencem aos autênticos gêneros Feldmannia e Hincksia, já que não se agruparam com as respectivas espécies-tipo dos gêneros, e, portanto, devem ser transferidos para o novo gênero. As análises com os dois marcadores moleculares demonstraram que \"F.\" irregulares, \"F. irregulares\" 1 e \"F. irregulares\" 2, previamente citados sob uma única espécie (F. irregulares), representam três entidades taxonômicas independentes. Sequências do COI-5P de F. irregulares da Itália, considerada próxima à localidade tipo (Mar Adriático), confirmaram que parte do material analisado deve ser mantido sob o epíteto irregulares, enquanto duas novas espécies devem ser propostas para a ciência para acomodar \"F. irregulares\" 1 e \"F. irregulares\" 2. As análises moleculares com o COI-5P dividiu \"F.\" mitchelliae em três agrupamentos com alta divergência genética e variabilidade morfológica indicando que \"F.\" mitchelliae forma um complexo. Uma sequência de \"F.\" mitchelliae procedente dos EUA (Carolina do Norte), próxima à localidade tipo (Massachusetts), gerada no presente estudo, confirmou que o material brasileiro deve ser descrito sob o epíteto mitchelliae, porém acomodado sob um novo gênero. Nossos resultados moleculares demonstraram claramente que o gênero Acinetospora não é monofilético. Acinetospora filamentosa é citada pela primeira vez para o Oceano Atlântico e foi revelada por meio de dados moleculares, tanto pelo COI-5P quanto pelo rbcL. A espécie Acinetospora crinita referida previamente para o litoral sudeste do Brasil não foi recoletada neste estudo. Diferenças morfológicas nas estruturas pluriloculares entre as duas espécies e ausência de monosporângios em A. filamentosa, descritos como típico apenas para A. crinita, confirmaram a ocorrência de A. filamentosa para o Atlântico. Nossos resultados com o rbcL revelaram que a família Asteronemataceae não é monofilética. O táxon \"Asteronema\" breviarticulatum se agrupou com Asterocladon lobatum, espécie tipo do gênero, e deve ser alocado na família Asterocladaceae, assim como transferido para o gênero Asterocladon propondo-se uma combinação nova para resolver o posicionamento taxonômico dessa espécie. A alta divergência genética verificada para os marcadores COI-5P e rbcL demonstraram que Bachelotia antillarum é uma espécie críptica. A utilização da ferramenta molecular no estudo de algas pardas filamentosas na região sudeste do Brasil foi fundamental para desvendar a sua diversidade, que comprovadamente estava subestimada, assim como melhor delimitar seus gêneros e espécies e revelar espécies crípticas. Os dados aqui apresentados são pioneiros e constituem uma fonte relevante de informação sobre a taxonomia e sistemática deste grupo de algas pardas. Mais investigações por meio de uma ampla revisão, especialmente da família Acinetosporaceae, uma maior amostragem no litoral brasileiro e inclusão de mais gêneros de algas pardas filamentosas nas análises podem ainda mudar o panorama da classificação desse grupo<br>Filamentous brown algae (Phaeophyceae) constitute an essentially marine group that display an extremely simple morphology. The taxonomic identification of these algae is very difficult when based only on morphological characters, due to the high incidence of phenotypic plasticity. In Brazil, no systematic study using molecular data has investigated their representatives. In this context, this study aims to investigate the diversity of filamentous brown algae of the genera Acinetospora, Asteronema, Bachelotia, Ectocarpus, Hincksia and Feldmannia for the first time in Brazil, applying the molecular approach coupled with morphological data. The sampling sites covered the southeastern region of Brazil, including the upwelling area of the Rio de Janeiro and Espírito Santo coasts, which include almost all the filaments of brown algae mentioned for the country. The DNA barcode mitochondrial marker, COI-5P, and the plastid marker for phylogenetic inferences, rbcL, were sequenced. The molecular and morphological studies allowed the recognition of 10 taxa on the Brazilian southeastern coast, out of which eight taxa correspond to the order Ectocarpales, and two to the order Scytothamnales. Ectocarpales is represented by the families Acinetosporaceae (Acinetospora filamentosa, \"Feldmannia\" irregularis, \"Feldmannia irregularis\" 1, \"Feldmannia irregularis\" 2, \"Feldmannia\" mitchelliae, \"Hincksia\" conifer and Hincksia sandriana), and Ectocarpaceae (Ectocarpus fasciculatus). The order Scytothamnales, in turn, includes the families Asteronemataceae (\"Asteronema\" breviarticulatum) and Bachelotiaceae (Bachelotia antillarum) The Acinetosporaceae family is non-monophyletic and was divided into two clusters: Acinetosporaceae 1 for which the family name should be retained, included the type species of the family (Acinetospora crinite) and most of the Brazilian representatives; and Acinetosporaceae 2 for which a new family should be proposed, included the genera Feldmannia, Hincksia and Pylaiella represented by their respective type species, Feldmannia lebelli, Hincksia hincksiae and Pylaiella litorallis. Hincksia sandriana was the only species studied that grouped in the clade of the authentic genus Hincksia. Besides, this is the first record of H. sandriana for Brazil, which constitutes a case of recent introduction. For the other representatives of Acinetosporaceae 1, except Acinetospora, a new genus for science should be proposed. The taxa \"H.\" conifer, \"F.\" irregularis, \"F. irregularis\" 1, \"F. irregularis\" 2 and \"F.\" mitchelliae do not belong to the authentic genera Feldmannia and Hincksia, since they did not group with the respective generitypes. Therefore, should be transferred to the new genus. Analyzes applying both molecular markers showed that \"F.\" irregularis, \"F. irregularis\" 1 and \"F. irregularis\" 2, previously cited as a single species (F. irregularis), constitute three independent taxonomic entities. COI-5P sequences of F. irregularis from Italy, close to the type locality (Adriatic Sea), demonstrate that part of the analyzed material should be maintained under the epithet irregularis, whereas two new scientific species should be proposed to accommodate \"F. irregularis \"1 and \" F. irregularis \"2. COI-5P molecular analyzes divided \"F.\" mitchelliae into three clusters with high genetic divergence and morphological variability indicating that \"F.\" mitchelliae corresponds to a species complex. A sequence of \"F. mitchelliae from the United States (North Carolina), near the type locality (Massachusetts), obtained and included in the present study, confirmed that the Brazilian material should be described under the epithet mitchelliae and transferred to a new genus. Our molecular results have clearly demonstrated that the genus Acinetospora is non-monophyletic. Acinetospora filamentosa is for the first time mentioned for the Atlantic Ocean and was revealed by molecular data, both by COI-5P and rbcL. The species Acinetospora crinite recorded on the southeastern coast of Brazil was not collected in this study. Morphological differences in plurilocular structures between two species and absence of monosporangia in A. filamentosa, described as typical only for A. crinite, confirmed the occurrence of A. filamentosa for the Atlantic. Our results with the rbcL revealed that the family Asteronemataceae is non-monophyletic. \"Asteronema\" breviarticulatum was grouped with Asterocladon lobatum, the type species of the genus, and should be transferred to the genus Asterocladon and to the family Asterocladaceae. Consequently, a new combination should be proposed to solve taxonomic placement of this species. The high genetic divergence observed for the COI-5P and rbcL markers demonstrated that Bachelotia antillarum is a cryptic species. The use of the molecular tool in the study of filamentous brown algae in the southeastern region of Brazil was fundamental to uncover their diversity, previously underestimated, as well as to allow a better delimitation of their genera and species. The innovative data presented here constitute a relevant source of information to the taxonomy and systematics of filamentous brown algae. More investigations through a broad review, especially of the Acinetosporaceae family, a wider sampling in the Brazilian coast and the inclusion of more genera of filamentous brown algae in the analyses can still change the classification scenario of this group

Submitted by Clebson Anjos (clebson.leandro54@gmail.com) on 2016-03-29T18:44:13Z No. of bitstreams: 1 arquivototal.pdf: 4614259 bytes, checksum: e4765945b6c16211d7771a473b84ad25 (MD5)<br>Made available in DSpace on 2016-03-29T18:44:13Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4614259 bytes, checksum: e4765945b6c16211d7771a473b84ad25 (MD5) Previous issue date: 2013-12-05<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>Marine biodiversity is presented as a promising source of new substances with high biological potential. Among the many organisms that inhabit the marine environment, we stress the brown algae belonging to the family Dictyotaceae. Genus Canistrocarpus was recently established, and some algae Dictyota formerly were reclassified as Canistrocarpus. This work describes the results of the phycochemical study of Canistrocarpus cervicornis (formerly classified as Dictyota pulchella), and the evaluation of the phycochemical profile of C. cervicornis collected on the coast of Paraíba and the coast of Rio de Janeiro, which contributed to the correct name of Dictyota pulchella as Canistrocarpus cervicornis. Alga samples were collected at Bessa Beach (coordinates 07º04'01 '' S and 34º49'35 '' W), city of João Pessoa (PB) in August 2010 and December 2012. The material was dried at room temperature and extraction was performed with CH2Cl2 : MeOH (2:1). The material was dried at room temperature in fresh air and extraction was performed with CH2Cl2: MeOH (2:1). The extract obtained the first collection was subjected to vacuum filtration on silica gel with solvent hexane, ethyl acetate and methanol in increasing gradient of polarity. The fraction hexane : ethyl acetate (85:15) was subjected to column chromatography yielded one new natural product, the dolastane diterpene 4,7-diacetoxy dichotenone A. The extract resulting from the second collection was divided in two parts. The first part was subjected to column chromatography resulted in the isolation of a known dolastane diterpene, 4-acetoxy-14-hidroxydolast-1(15),7,9-triene. A second aliquot of the extract was acetylated and subjected to column chromatography, which led to the isolation of three diterpenes, one dolastane unpublished in the literature, 4-desoxy-amijidictyol and two known secodolastanes, isolinearol acetate and indicol. Chemical constituents isolated were identified by spectroscopic methods 1H and 13C-1D and 2D NMR, optical rotation and comparison with literature data. This study contributed to the chemotaxonomy of the tribe Dictyoteae, especially C. cervicornis.<br>A biodiversidade marinha apresenta-se como uma fonte promissora de novas substâncias com grande potencial biológico. Dentre os diversos organismos que habitam o ambiente marinho, merecem destaque as algas pardas pertencentes à família Dictyotaceae e gênero Canistrocarpus. Este gênero foi instituído recentemente, e algumas algas anteriormente denominadas Dictyota foram reclassificadas como Canistrocarpus. O presente trabalho descreve os resultados do estudo ficoquímico de Canistrocarpus cervicornis (anteriormente classificada como Dictyota pulchella), envolvendo a avaliação do perfil ficoquímico de C. cervicornis coletada no litoral da Paraíba e no litoral do Rio de Janeiro. Este estudo contribuiu para a correta denominação da então D. pulchella em C. cervicornis. As amostras da alga foram coletadas na Praia do Bessa (coordenadas 07º04’01’’ S e 34º49’35’’ W) na cidade de João Pessoa (PB), em agosto de 2010 e em dezembro de 2012. A secagem foi realizada a temperatura ambiente, em local arejado e a extração procedida com CH2Cl2:MeOH (2:1). O extrato resultante da primeira coleta foi submetido a uma filtração a vácuo em sílica gel com os solventes hexano, acetato de etila e metanol em gradiente crescente de polaridade. A fração hexano:acetato de etila (85:15) foi submetida a cromatografia em coluna, de onde se obteve um novo produto natural, o diterpeno dolastano 4,7-diacetoxi de dichotenona A. O extrato resultante da segunda coleta foi dividido em duas partes. Uma alíquota foi submetida à cromatografia em coluna, de onde se obteve o diterpeno dolastano conhecido 4-acetoxi-14-hidroxidolasta-1(15),7,9-trieno. A segunda alíquota do extrato foi acetilada e submetida a cromatografias em coluna, o que levou ao isolamento de três diterpenos, sendo um dolastano inédito na literatura, o 4-desoxi-amijidictyol e dois secodolastanos conhecidos, o acetato de isolinearol e o indicol. Os constituintes químicos isolados foram identificados por análises espectroscópicas de RMN 1H e 13C uni e bidimensionais, rotação ótica, e comparação com dados da literatura. Este estudo contribuiu para a quimiotaxonomia da tribo Dictyoteae, em especial de C. cervicornis.

Les systèmes de complexes récifaux de l’archipel de la Nouvelle-Calédonie sont explorés depuis près de quarante années pour leur exceptionnelle biodiversité. En effet, de part une position sous-tropicale unique, proche de zones tectoniques actives et du sous-continent Australien, les récifs et lagons néo-calédoniens abritent une importante faune et flore marine relativement protégée des perturbations climatiques. Ces organismes marins se sont avérés être un réservoir considérable de molécules des plus originales et ayant une forte propension à présenter un intérêt thérapeutique notamment dans le cadre du traitement du cancer. L’objectif de cette thèse était de poursuivre cette quête en puisant les substances naturelles dans des macroalgues de Nouvelle-Calédonie. La modulation de la mort cellulaire programmée a notamment été ciblée. Ainsi, les travaux réalisés sur sept espèces de macroalgues rouges (Rhodophyceae) et brunes (Phaeophyceae) collectées dans le lagon Sud de la Nouvelle-Calédonie (arrêté N°197-2016/ARR/DENV) ont permis de révéler leur potentiel dans l’inhibition de la prolifération de cellules cancéreuses en culture. Une espèce de macroalgue rouge a plus particulièrement été travaillée et a conduit à la caractérisation de deux molécules bioactives, dont une n’avait pas été décrite auparavant. L’étude de leur mécanisme d’action cellulaire a révélé que celles-ci pouvaient constituer de nouvelles pistes thérapeutiques intéressantes dans la recherche de nouveaux traitements en chimiothérapie en tant qu’agents antimitotiques inhibiteurs de kinase. Des activités biologiques très intéressantes ont également été révélées pour des fractions issues de deux espèces de macroalgues brunes démontrant une sélectivité significative pour les cellules cancéreuses. Inscrite dans la continuité de multiples bioprospections menées dans les lagons de Nouvelle-Calédonie à la recherche de produits naturels marins d’intérêt thérapeutique, cette thèse de doctorat témoigne du potentiel de plusieurs espèces de Rhodophyceae et Phaeophyceae jusqu’alors très peu explorées chimiquement<br>Marine zones associated with coral reef systems of the New Caledonia archipelago have been investigated for almost forty years with respect to their plant and invertebrate biodiversity and chemodiversity. In particular, thanks to their unique subtropical position close to tectonically active zones and to the Australian subcontinent, the complex reef systems of New Caledonia’s lagoons are home to a highly diverse marine fauna that is relatively protected from climatic disturbances. This is reflected by the score of novel bioactive molecules that have been discovered and characterized, several of which have been actively investigated for their antineoplastic and antitumoral potential activities. We paid particular attention to macroalgal species that induce programmed cell death, as an approach to detecting original anticancer bioactivities. Seven species of red (Rhodophyceae) and brown (Phaeophyceae) macroalgae collected in the South lagoon of New Caledonia (decree N°197-2016/ARR/DENV) have demonstrated interesting in vitro anticancer activity. In particular, one red macroalgal species led to the characterization of two bioactive natural products, the structure of one of which has not been described to date. Biological tests have shown that these two compounds could be promising candidates as antimitotic kinase inhibitors agents for the development of targeted anticancer chemotherapies. Interesting biological activities have also been revealed from several molecular isolates from two species of brown macroalgae, showing high selectivity towards non-cancerous cells. In the continuing investigations of the therapeutic potential of natural products isolated from New Caledonian marine organisms, this doctoral thesis has highlighted the therapeutic potential of several species of Rhodophyceae and Phaeophyceae which has hitherto been largely unexplored

Le développement, la reproduction et la survie d’un organisme, dépendent de son environnement physique et/ou écologique. La sélection en faveur de certains traits d’histoire de vie découle donc de la stabilité de l’environnement (i. E. Reproduction sexuée versus asexuée). La stratégie de reproduction d’une espèce est par conséquent susceptible de se modifier en fonction des changements environnementaux, pouvant survenir en limite d’aire de distribution qui se caractérisent par des fluctuations abiotiques plus importantes. Les grandes algues brunes (Phaeophyceae, Laminariales) sont des espèces structurant les communautés benthiques marines. Elles présentent un cycle de reproduction hétéromorphe avec alternance de phase haploïde microscopique (gamétophyte) et de phase diploïde macroscopique (sporophyte). Les connaissances sur la biologie et la distribution géographique de la plupart de ces espèces n’étaient basées jusqu’à présent que sur l’étude des sporophytes. Mes travaux de thèse ont permis de mettre en évidence l’importance de ces gamétophytes dans le maintien des populations, en comparant les modes de reproduction de trois espèces de laminaires. Les résultats suggèrent que le déterminisme du sexe est principalement génétique et que l’effet de la température de l’eau de mer sur la phase microscopique peut expliquer les distributions géographiques de certaines espèces. Par ailleurs, différents stratégies reproductives ont été observées au sein et entre espèces suggérant l’existence de phénomènes d’adaptations locales. En particulier, en limite d’aire de distribution des espèces, nos résultats montrent l’existence de la parthénogenèse géographique.