Letteratura scientifica selezionata sul tema "Toxic diatoms"
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Articoli di riviste sul tema "Toxic diatoms"
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Kumar, Rohit, Melania Paturzo, Angela Sardo, Ida Orefice, Qiucheng Yu, Andrea Rubano e Domenico Paparo. "Toxic Effect of Metal Doping on Diatoms as Probed by Broadband Terahertz Time-Domain Spectroscopy". Molecules 27, n. 18 (11 settembre 2022): 5897. http://dx.doi.org/10.3390/molecules27185897.
Testo completoAbstract (sommario):
The global marine environment is increasingly affected by human activities causing climate change, eutrophication, and pollution. These factors influence the metabolic mechanisms of phytoplankton species, such as diatoms. Among other pollutant agents, heavy metals can have dramatic effects on diatom viability. Detailed knowledge of the interaction of diatoms with metals is essential from both a fundamental and applicative point of view. To this aim, we assess terahertz time-domain spectroscopy as a tool for sensing the diatoms in aqueous systems which mimic their natural environment. Despite the strong absorption of terahertz radiation in water, we show that diatoms can be sensed by probing the water absorption enhancement in the terahertz range caused by the water–diatom interaction. We reveal that the addition of metal dopants affects this absorption enhancement, thus enabling the monitoring of the toxic effects of metals on diatoms using terahertz spectroscopy. We demonstrate that this technique can detect the detrimental effects of heavy metals earlier than conventional methods such as microscopy, enzymatic assays, and molecular analyses aimed at assessing the overexpression of genes involved in the heavy metal-stress response.
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Chasapis, Christos T., Massimiliano Peana e Vlasoula Bekiari. "Structural Identification of Metalloproteomes in Marine Diatoms, an Efficient Algae Model in Toxic Metals Bioremediation". Molecules 27, n. 2 (7 gennaio 2022): 378. http://dx.doi.org/10.3390/molecules27020378.
Testo completoAbstract (sommario):
The biosorption of pollutants using microbial organisms has received growing interest in the last decades. Diatoms, the most dominant group of phytoplankton in oceans, are (i) pollution tolerant species, (ii) excellent biological indicators of water quality, and (iii) efficient models in assimilation and detoxification of toxic metal ions. Published research articles connecting proteomics with the capacity of diatoms for toxic metal removal are very limited. In this work, we employed a structural based systematic approach to predict and analyze the metalloproteome of six species of marine diatoms: Thalassiosira pseudonana, Phaeodactylum tricornutum, Fragilariopsis cylindrus, Thalassiosira oceanica, Fistulifera solaris, and Pseudo-nitzschia multistriata. The results indicate that the metalloproteome constitutes a significant proportion (~13%) of the total diatom proteome for all species investigated, and the proteins binding non-essential metals (Cd, Hg, Pb, Cr, As, and Ba) are significantly more than those identified for essential metals (Zn, Cu, Fe, Ca, Mg, Mn, Co, and Ni). These findings are most likely related to the well-known toxic metal tolerance of diatoms. In this study, metalloproteomes that may be involved in metabolic processes and in the mechanisms of bioaccumulation and detoxification of toxic metals of diatoms after exposure to toxic metals were identified and described.
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Hetko, Dominika, Małgorzata Witak e Magdalena Bełdowska. "The Relationship between Total Mercury, Its Fractions and Species Diversity of Diatom Taphocoenoses Deposited in Surface Sediments (Southern Baltic Sea)". Water 15, n. 22 (9 novembre 2023): 3907. http://dx.doi.org/10.3390/w15223907.
Testo completoAbstract (sommario):
Mercury is a toxic metal that in excessive amounts negatively affects the human nervous system. It can biomagnify to enrich successive levels of the trophic web with higher and higher concentrations of Hg. Diatoms are cosmopolitan microalgae that represent the base of the trophic web. The objective of this study was to determine the importance of diatoms in the accumulation of Hg in surface sediments in the example of Puck Lagoon (southern Baltic Sea). The study verified the relationship of mercury forms with diatoms’ characteristic salinity groups and individual diatom species. The identified diatom flora permitted the distinguishment of three regions with different salinity preferences. The obtained results suggest that, together with organic matter and fine sediment fraction, diatoms are an important element of the marine environment in accumulating Hg. Area I, dominated by euhalobous and mesohalobous diatom species, was characterized by a high statistically significant correlation of mesohalobous with HgSO4, Hg in complexes with organic matter and HgS. In Area II, associated with the highest Hg concentrations (ca. 100 ng g−1), euhalobous showed a statistically significant linear correlation with HgSO4. In contrast, in Area III, the freshwater diatom community was associated with stable Hg forms. The identified species showed a connection with labile forms of Hg that can undergo biomagnification.
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Thessen, A. E., T. M. Soniat, Q. Dortch e G. J. Doucette. "Crassostrea virginica grazing on toxic and non-toxic diatoms". Toxicon 55, n. 2-3 (febbraio 2010): 570–79. http://dx.doi.org/10.1016/j.toxicon.2009.10.011.
Testo completo
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Giri, Tapas, Umesh Goutam, Aditi Arya e Shristy Gautam. "Effect of Nutrients on Diatom Growth: A Review". Trends in Sciences 19, n. 2 (3 gennaio 2022): 1752. http://dx.doi.org/10.48048/tis.2022.1752.
Testo completoAbstract (sommario):
Diatoms are one of the unicellular algae with a rare presence of unaltered, durable, transparent and species-specific silica frustules that persist even after cell death in the deposits of water bodies. Diatom has high capacity for absorption of metals for maintaining the water quality and high rate of multiplication. These characters promoted the use of this microbial biomass for effluent detoxification. These diatoms can also solve metal toxicity problems in aquatic ecosystems in the water polluted environment. In the present review, the focus is on several nutrients (nitrogen, phosphorus, iron and silica) that are essential for the growth of diatoms at very low concentrations, but most of them are toxic at high concentrations. It also shows the relationship between heavy metal stress and lipid body induction which may be a valuable indicator for the evaluation of heavy metal contamination of fluvial ecosystems.
HIGHLIGHTS
Diatoms are eukaryotic, unicellular, photosynthetic, silica-containing microscopic algae with distinct geometric forms
Diatoms are used for biomonitoring purposes for taxonomic and morphological properties of ecosystems, community and human disturbances
Diatoms are also the primary producer of oil in the world responsible for fixing 25 % of CO2 and 30 % of crude oil diatoms
Many diatoms are appropriate for lipid development up to 70 % of their body volume and are investigated for biofuel as a hotspot
GRAPHICAL ABSTRACT
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Tanković, Mirta Smodlaka, Ana Baričević, Victor Stinga Perusco, Roland R. Melzer, Alejandro Izquierdo Lopez, Jana Sophie Dömel, Martin Heß, Nataša Kužat, Daniela Marić Pfannkuchen e Martin Pfannkuchen. "Experimental evidence for shaping and bloom inducing effects of decapod larvae of Xantho poressa (Olivi, 1792) on marine phytoplankton". Journal of the Marine Biological Association of the United Kingdom 98, n. 8 (26 luglio 2018): 1881–87. http://dx.doi.org/10.1017/s0025315418000449.
Testo completoAbstract (sommario):
To study zooplankton–phytoplankton relationships in the diatom-dominated plankton communities of the northern Adriatic we performed feeding experiments with diatoms and zoea I larvae of the brachyuran Xantho poressa. We found that zoea I of X. poressa feed on diatoms of different forms (centric, pennate, colony forming, single celled, with or without setae) and size classes. In a laboratory setup, we presented the zoeas with a mix of diatom species similar to communities observed during blooms regularly found in the northern Adriatic. We report that the grazing activity resulted in a decrease of the relative abundance of the toxic diatom Pseudo-nitzschia calliantha. For the colonial, bloom-forming diatom Skeletonema marinoi our results show a chain length reduction in the presence of zoea I. Of particular interest is the observation that the presence of larvae also resulted in an increased growth rate and abundance of S. marinoi, which resembles bloom induction by grazer presence.
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Khanaychenko, A. N. "How diatom Cylindrotheca closterium vanquish invasive copepod Oithona davisae". Marine Biological Journal 3, n. 3 (28 settembre 2018): 77–85. http://dx.doi.org/10.21072/mbj.2018.03.3.08.
Testo completoAbstract (sommario):
Some diatoms are rich food for herbivorous copepods, while others are toxic for their recruitment. No negative effect of diatom Cylindrotheca closterium was ever observed for copepods, and some estuarine copepods preferred it as a food. Data on grazing diatoms by abundant now in the Black Sea coastal waters invasive copepod Oithona davisae are still contradictory. Interaction of O. davisae and C. closterium, both having high colonizing potential and both typical for coastal waters, was studied in experimental culture. Two weeks after inoculation of C. closterium the cultured O. davisae was drastically fouled by globulous conglomerates of diatom cells. Diatom cells in “colonies” on copepod exoskeleton were interconnected by means of adhesive substances at one of their flexible ends at the point-wise areas at various parts of copepods exoskeleton, and the opposite flexible ends performed various circular roll-over fan-shaped movements around the axis passing through the point of their attachment. “Colonies” behaved as integrated aggressive organisms against any approaching flagellate and prevented normal locomotion of copepods. Herein we present the first report on epizoic behavior of C. closterium: quick disastrous colonization of alive copepods O. davisae by diatom “colonies” led to total extinction of cyclopoid experimental population while alive diatoms formed dense network on copepods degenerative tissues.
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Perrin, C. J., e M. L. Bothwell. "Chlorate Discharges from Pulp Mills: An Examination of Effects on River Algal Communities". Water Quality Research Journal 27, n. 3 (1 agosto 1992): 473–86. http://dx.doi.org/10.2166/wqrj.1992.032.
Testo completoAbstract (sommario):
Abstract To avoid the formation of organochlorine compounds in pulp products and effluents discharged into the environment, there is a trend in the North American pulping industry to change from molecular chlorine to chlorine dioxide bleaching. However, chlorate (ClO3−) formed during chlorine dioxide bleaching is known to have toxic effects in some marine algae and has been implicated in environmental problems in the Baltic Sea. This study examined the potential effects of chlorate on natural freshwater, riverine diatom communities characteristic of many rivers in western Canada. Under low ambient river nitrate concentrations (ca. 10 µg•L−1 NO3−N), chlorate additions of up to 500 µg•L1 ClO3 did not reduce the specific growth rates (µ) or change the taxonomic composition of the attached riverine diatom community. The lack of chlorate toxicity to freshwater diatoms suggests that the nitrate uptake and/or reduction mechanism(s) of freshwater diatoms have much higher affinities for NO3 than ClO3 compared to many marine macroalgae. These results indicate that chlorate discharged from new or upgraded pulpmills into freshwater river environments will not cause environmental changes to the dominant algal producers such as diatoms.
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Delasoie, Joachim, Natasa Radakovic, Aleksandar Pavic e Fabio Zobi. "Neovascularization Effects of Carbon Monoxide Releasing Drugs Chemisorbed on Coscinodiscus Diatoms Carriers Characterized by Spectromicroscopy Imaging". Applied Sciences 10, n. 20 (21 ottobre 2020): 7380. http://dx.doi.org/10.3390/app10207380.
Testo completoAbstract (sommario):
Silica microparticles made of diatomaceous earth have become particularly attractive materials for designing drug delivery systems. In order to investigate the use of natural diatoms as drug scaffolds for carbon monoxide releasing molecules (CORMs), we evaluated the chemisorption of the cis-[Re(CO)2Br4]2− complex (ReCORM-2) and its vitamin B12 derivative (B12-ReCORM-2) on Coscinodiscus frustules by 3D FT-IR spectroscopic imaging, and the drugs’ neovascularization effects in vivo in the zebrafish (Danio rerio) model. By mapping the symmetric Re-C≡O υ(CO) stretching vibration of the CORMs in the 2000 cm−1 region, we found that the drugs are mostly localized at the girdle band of the diatom frustule. Both ReCORM-2 and B12-ReCORM-2 retain their CO-releasing ability when chemisorbed on the diatoms. When applied in vivo at doses ≥25 µM, the molecules markedly reduced intersegmental and subintestinal vessels development in zebrafish, revealing high anti-angiogenic potential. In addition, diatom frustules did not provoke any toxic in vivo response in the zebrafish embryos, including inflammation. Overall, our results indicate that: (1) CORMs chemisorbed on diatom frustules retain their CO-releasing abilities; (2) both CO-releasing molecules show a concentration-dependent effect on the neovascularization in developing zebrafish; (3) silicate frustules are not toxic and could be used as CORMs drug carriers.
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Ianora A, , SA, A., A. Miralto e SA Poulet. "Are diatoms good or toxic for copepods?" Marine Ecology Progress Series 177 (1999): 305–8. http://dx.doi.org/10.3354/meps177305.
Testo completoTesi sul tema "Toxic diatoms"
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PICHIERRI, SALVATORE. "Interactions between the toxic benthic dinoflagellate Ostreopsis cf ovata and marine diatoms". Doctoral thesis, Università Politecnica delle Marche, 2017. http://hdl.handle.net/11566/245283.
Testo completoAbstract (sommario):
La produzione di metaboliti secondari è stata osservata in molti organismi fitoplanctonici, incluse le diatomee che sono in grado di rilasciare diversi tipi di aldeidi polinsaturi (PUAs). Diversi studi hanno descritto la capacità di questi composti di influenzare la riproduzione invertebrati e la crescita del fitoplancton. Tuttavia, questi studi si sono concentrati sul ruolo ecologico delle PUAs principalmente in ambiente pelagico e nessuna informazione è disponibile sul loro effetto in quello bentonico.
Ostreopsis cf. ovata è un dinoflagellato tossico bentonico che causa massicce fioriture in diverse aree costiere del Mar Mediterraneo incluso il nord Adriatico. In questa tesi ho investigato le interazioni, mediate da composti allelopatici, tra alcune diatomee bentoniche e Ostreopsis.
I risultati della tesi di dottorato hanno messo per la prima volta in evidenza la produzione di PUAs in tre diatomee bentoniche comuni del nord Adriatico, cioè Proschkinia complanatoides, Tabularia affinis, Navicula sp . Quasi la totalità delle PUAs prodotte da Navicula sp. era costituita da catene medio corte mentre i profili di T. affinis e P. complanatoides apparivano più diversificati.
Il secondo esperimento, ha mostrato una marcata inibizione della crescita di O. cf. ovata quando coltivato in presenza di tre PUAs commerciali. Con le catene lunghe sono stati osservati effetti più deleteri rispetto alle catene corte e l'analisi morfologica ha rivelato la presenza di forme aberranti (perdita mobilità, contrazione del citoplasma e formazione di vescicole anomale), danno al DNA, diminuzione delle rese quantiche del fotosistema II e aumento del contenuto di lipidi.
Il mio ultimo studio ha sottolineato l'inibizione della crescita di O. cf. ovata quando quando veniva esposto ai filtrati di cinque diatome produttrici di PUA, due planctoniche (Skeletonema marinoi, Thalassiosira sp.) e tre bentoniche (P. complanatoides, Navicula sp. e T.affinis), Oltre a questi effetti, è stato osservato la presenza di forme anomale e danno al DNA.The production of secondary metabolites was reported in many phytoplanktonic organisms including diatoms that have been shown to release different types of polyunsaturated aldehydes (PUAs). Several studies described the ability of these compounds to affect the invertebrate reproduction and the phytoplankton growth. However, these studies have focused the ecological role of PUAs primarily in pelagic environment and no information is available on their effect in the benthic one. Ostreopsis cf. ovata is a benthic toxic dinoflagellate causing massive blooms in different coastal areas of the Mediterranean Sea including the northern Adriatic Sea. In this thesis we investigated the interactions between some benthic diatoms and Ostreopsis mediated by allelopathic compound. The results of PhD thesis highlighted for the first time the production of PUAs compounds in three common benthic diatoms of the northern Adriatic Sea, i.e. Proschkinia complanatoides, Tabularia affinis, Navicula sp.. Almost the totality of PUAs produced by Navicula sp. consisted of low or medium-chained while the PUAs profiles of T. affinis and P. complanatoides appear more diversified. In a second experiment, we demonstrated a marked inhibition of of O. cf. ovata growth when it was grown in the presence of three commercial PUAs. A higher deleterious effects was observed with longer-chain molecules than with shorter-chain ones and the morphological analysis revealed presence of aberrant forms (motionless, contraction of cytoplasm and formation of abnormal vesicle-like structures), DNA damage, decrease of maximum and effective quantum yields of photosystem II and increase of lipid content. My last study pointed out the inhibition of O. cf. ovata growth when it was exposed to the filtrates of five diatom-PUA producers, two planktonic (Skeletonema marinoi, Thalassiosira sp.) and three benthic (P. complanatoides, Navicula sp. and T.affinis), In addition to these effects, the presence of abnormal forms and a DNA damage were observed.
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Toropov, Pavel. "Potential toxic effects of Bracken (Pteridium aquilinum (L) Kuhn) on invertebrates and diatoms in Welsh upland streams". Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250370.
Testo completoAbstract (sommario):
This thesis examines a wide range of domestic novels, from Bram Stoker's Dracula (1897) to Woolf's Mrs Dallowa~ (1925), in order to explore their intensified concern with the aesthetlc value of domestic scene. The representation of the house in these works is viewed as an ideological strategy of containment, effected not only by narrative exclusions but also by the literary mode of the narrative. The domestic novel at the turn of the century does not necessarily produce an image of the house but presents a writing of space which interacts with architectural aesthetics in a discourse of the house beautiful. Critical analysis of the cultural and economic contradictions of this discourse indicates the way that the domestic novel is shaped by the colonial situation and at the same time opens out the complexity of its construction of feminine subjectivity. The late 19th century produced simplified spacious design in a reaction to the Victorian concept of the civilised house. The fictional and architectural ideal of a unified house form is, however, an assertion of identity and, in this sense, a renegotiation of the opposition between the E~gl~sh home and foreign or colonial 'otherness ' • This mapping is effected w~th~n the ideological imperative of the question of colonial trade. The flctl0nal emphasis on woman's relation to the house deals with her displacement in the commodity world of the aestheticised house. Yet the privilege given to the English word home lends to woman's sensual appreciation of the house, or creation of setting for herself, an importance which limits th~ ~mplied critique. Furthermore, feminine experience of habitation is relfled by the authoritive definition of the house in the interacting aesthetics of architecture and literature. The domestic novel thus mystifies new feminine roles, particularly the role of entertainment and even the attempt to demystify such ideals of habitation to . some extent colludes with the mystique by seeking the truth of woman's unspoken experience of the house
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GIULIETTI, SONIA. "Unveiling the hidden biodiversity of potentially toxic diatoms in the NW Adriatic Sea through integrated taxonomy approach". Doctoral thesis, Università Politecnica delle Marche, 2021. http://hdl.handle.net/11566/289742.
Testo completoAbstract (sommario):
Pseudo-nitzschia è tra i generi di diatomee più noti e studiati, poiché tra tutte le 56 specie accettate, 26 sono in grado di produrre una neurotossina (acido domoico) responsabile di una biointossicazione (Amnesic Shellfish Poisoning) nell’uomo. La diversità e l’andamento stagionale delle specie di Pseudo-nitzschia sono stati analizzati per la prima volta nella stazione costiera del transetto Senigallia-Susak (LTER) nel NW Adriatico dal 1988 al 2020, attraverso un approccio tassonomico integrato basato su analisi ultrastrutturale e molecolare. Almeno 6 morfotipi sono stati identificati tramite osservazione all'ottico: P. cf. delicatissima, P. cf. pseudodelicatissima, P. multistriata, P. cf. fraudulenta, P. pungens and P. cf. galaxiae. L’analisi IndVal ha rivelato che P. cf. delicatissima e P. cf. pseudodelicatissima sono taxa indicatori in primavera ed estate rispettivamente. P. cf. fraudulenta e P. pungens erano taxa indicatori della stagione invernale ed erano correlate negativamente con la temperatura e positivamente con le concentrazioni del DIN. P. multistriata proliferava in autunno ed era l’unica specie positivamente correlata con le concentrazioni di silicati. Negli anni 2018-2020 sono stati isolati, con frequenza mensile, 138 ceppi monoclonali di Pseudo-nitzschia. Combinando le analisi al microscopio elettronico a trasmissione con i risultati dell'albero filogenetico ottenuto con le sequenze LSU e ITS rDNA, sono state confermate le identità di sei specie di Pseudo-nitzschia che formano 6 distinti cluster: i.e. P. delicatissima, P. cf. arenysensis, P. calliantha, P. mannii, P. fraudulenta, P. pungens. Le analisi sul contenuto delle tossine non hanno rilevato la presenza di acido domoico in nessun ceppo. Inoltre, le analisi morfologiche di P. pungens hanno rivelato una sorprendente variabilità (sovrapposizione delle cellule in colonia, forma delle valve, morfologia dei poroidi in vista cingolare) che devia dalla forma nominale P. pungens. Infine, tramite l'osservazione sia dell'ultrastruttura del frustulo che delle sequenze molecolari (regione D1-D3 del LSU rDNA), è stata descritta Nitzschia gobbii sp. nov., una nuova diatomea planctonica con una porzione espansa al centro del frustulo e due lunghi rostri in vista valvare. Nei 30 anni di monitoraggio questa specie è stata frequentemente registrata ma forse anche erroneamente identificata come Cylindrotheca closterium o Pseudo-nitzschia galaxiae.Pseudo-nitzschia is among the most known and studied diatom genus, since among the total 56 accepted species, 26 produce a neurotoxin (i.e. domoic acid) responsible for human illness (i.e. Amnesic Shellfish Poisoning). The diversity and seasonality of Pseudo-nitzschia species were analyzed for the first time in the coastal station of the LTER-Senigallia-Susak transect in the northwestern Adriatic Sea from 1988 to 2020, by an integrated taxonomy approach, based on the ultrastructural and molecular analysis. At least six morphotypes have been detected by LM observations on field samples P. cf. delicatissima, P. cf. pseudodelicatissima, P. multistriata, P. cf. fraudulenta, P. pungens and P. cf. galaxiae. The IndVal analysis revealed that P. cf. delicatissima and P. cf. pseudodelicatissima were relevant taxa in spring and summer, respectively. P. cf. fraudulenta and P. pungens were relevant winter taxa and were negatively correlated with water temperature and positively with DIN. P. multistriata appeared in autumn and was the only species positively correlated with silicate concentrations. Monthly isolation of the highest possible number of strains were performed from 2018 to 2020, leading to isolate 138 strains. Transmission Electron Microscopy analysis and LSU rDNA phylogenetic tree confirmed the identity of six Pseudo-nitzschia species also clustering in six distinct lineages, i.e. P. delicatissima, P. cf. arenysensis, P. calliantha, P. mannii, P. fraudulenta, P. pungens. Domoic acid was not detected in any strain. P. pungens revealed a surprisingly wide morphological variability (e.g. overlap of cells in colonies, shape of valve, poroids’ morphology in girdle view) deviating from the nominal P. pungens. Finally, ultrastructural analysis and molecular evidence (D1-D3 region of LSU rDNA), allowed the description of Nitzschia gobbii sp. nov. a new planktonic diatom with an expanded central part of the frustule and two long rostra in valve view. This species commonly occurred during the investigated 30 years but possibly misidentified with Cylindrotheca closterium or with Pseudo-nitzschia galaxiae.
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Cziesla, Christopher A. 1969. "The transport and distribution of the toxic diatom Pseudo-nitzschia spp. in the Coos Bay estuary and the adjacent continental shelf". Thesis, Thesis (M.S.)--University of Oregon, 1998, 1999. http://hdl.handle.net/1794/9811.
Testo completoAbstract (sommario):
Typescript.
Includes vita and abstract.
Bibliography: Includes bibliographical references (leaves 84-88).
Description: x, 88 leaves : ill. ; 29 cm.Along the Oregon coast blooms of Pseudo-nitzschia spp. have been an almost annual occurrence since monitoring began in the late 80's. This study looks at the distribution of Pseudo-nitzschia spp., in relation to meteorological and oceanographic conditions. A series of transects (1995-98) were done in Coos Bay and over the adjacent continental shelf under a variety of oceanographic conditions. An intense sampling program was undertaken in June 1998, with simultaneous nearshore and in bay (Coos Bay) sampling, including a nearshore grid, 24 hour anchor station in the bay, and an in bay incoming tide drift study. The results suggest that blooms develop nearshore after upwelling events. In conditions of relaxed upwelling highest cell concentrations were found immediately adjacent to the coast in surface and mid-depth waters. At stations in Coos Bay, Pseudonitzschia spp. concentrations increased with the incoming tide. Nearshore phytoplankton populations were transported into the bay, initially in the more saline bottom waters, but were rapidly mixed throughout the water column by the turbulent flow in the channels. On ebbing tides there was a reduced number of phytoplankton in the water column, possibly indicating consumption by in bay filter feeders or sinking and deposition on the bottom.
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Pytlik, Nathalie, e Eike Brunner. "Diatoms as potential “green” nanocomposite and nanoparticle synthesizers: challenges, prospects, and future materials applications". Cambridge University Press, 2018. https://tud.qucosa.de/id/qucosa%3A70668.
Testo completoAbstract (sommario):
Diatoms are unicellular, eukaryotic microalgae inhabiting nearly all aquatic habitats. They are famous for their micro- and nanopatterned silicabased cell walls, which are envisioned for various technologic purposes. Within this review article, we summarize recent in vivo modifications of diatom biosilica with respect to the following questions: (i) Which metals are taken up by diatoms and eventually processed into nanoparticles (NPs)? (ii) Are these NPs toxic for the diatoms and––if so––what factors influence toxicity? (iii) What is the mechanism underlying NP synthesis and subsequent metabolism? (iv) How can the obtained materials be useful for materials science?
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Deschler, Marie. "Ιntéractiοns et cοmmunicatiοn chimique entre les diatοmées tοxiques du genre Ρseudο-nitzschia et les cοnsοmmateurs zοοplanctοniques". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMLH13.
Testo completoAbstract (sommario):
Les efflorescences d’algues toxiques (HAB), potentiellement favorisées par le réchauffement climatique et l’eutrophisation des écosystèmes côtiers, est un sujet de préoccupation majeur. C’est le cas des diatomées du genre Pseudo-nitzschia, dont certaines espèces produisent une neurotoxine, l’acide domoïque (AD), responsable d'intoxication amnésiante par les mollusques (ASP). Ces efflorescences ont des conséquences à la fois sanitaires et socio-économiques, les phénomènes ASP entrainant des interdictions de pêche, en particulier à la coquille Saint Jacques sur les côtes normandes. Les copépodes peuvent également véhiculer l’AD dans le réseau trophique. La plupart des études sur l’interaction entre Pseudo-nitzschia et les copépodes concernent des espèces arctiques. Cette thèse visait à approfondir cette interaction pour les espèces présentes sur les côtes normandes (France). Les résultats montrent des mécanismes de défense chez Pseudo-nitzschia en réponse aux prédateurs zooplanctoniques, dont l’induction de la production d’AD en présence de copépodes, observée pour la première fois chez P. australis, connue pour son fort potentiel ASP. En revanche, P. pungens et P. fraudulenta n’augmentaient pas leur production en présence de prédateurs, soulignant l’impossibilité d’extrapoler les données d’une espèce à l’autre ou d’un écosystème à l’autre. Une réponse morphologique, telle que la réduction de la taille des chaînes, a également été démontrée pour la première fois chez P. australis. Les réponses physiologique et morphologique chez P. australis étaient déclenchées à la fois par la présence directe de prédateurs et mais aussi uniquement par leurs signaux chimiques, présents dans le milieu. Ces réponses n’ont pas été associées à une sur-mortalité des copépodes. Par contre, une réduction de la nage basale et des modifications du transcriptome ont pu être mises en évidenceHarmful algal blooms (HAB), potentially favored by global warming and eutrophication of coastal ecosystems, are a major concern. This is the case for diatoms of the genus Pseudo-nitzschia, some species of which produce a neurotoxin, domoic acid (DA), responsible for amnesic shellfish poisoning (ASP). These efflorescences have both health and socio-economic consequences, with ASP phenomena leading to shellfish fishing bans, particularly for scallops on the Normandy coast. Zooplankton copepods can also carry DA through the food web. Most studies on the interaction between Pseudo-nitzschia and copepods have focused on Arctic species. The aim of this thesis was to investigate this interaction in greater depth for species present on the Normandy coast (France). The results show defense mechanisms in Pseudo-nitzschia in response to zooplanktonic predators, including induction of DA production, observed for the first time in P. australis, known for its high ASP potential. On the other hand, P. pungens and P. fraudulenta did not increase their production in the presence of predators, underlining the impossibility of extrapolating data from one species to another or from one ecosystem to another. A morphological response, i.e. chain size reduction, was also demonstrated for the first time in P. australis. Physiological and morphological responses in P. australis were triggered both by the direct presence of predators and solely by their cues, present in the environment. These responses were not associated with excess copepod mortality. However, a reduction in basal swimming and changes in the transcriptome were observed
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Delaney, Jennifer A. "Molecular Detection of the Toxic Marine Diatom Pseudo-nitzschia multiseries". Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3558.
Testo completoAbstract (sommario):
The marine diatom genus Pseudo-nitzschia includes species that produce domoic acid, a neurotoxin responsible for illness and mortality in both humans and marine wildlife. Because of the expertise and time required for the microscopic discrimination of species, molecular methods that monitor environmental concentrations of Pseudo-nitzschia provide a rapid alternative for the early detection of blooms and prediction of toxin accumulation. We have developed a nucleic acid sequence-based amplification with internal control RNA (IC-NASBA) assay and a quantitative reverse transcription PCR (qRT-PCR) assay for the detection of the toxic species P. multiseries targeting the ribulose- 1,5-biphosphate carboxylase/oxygenase small subunit (rbcS) gene. Both methods use RNA amplification and fluorescence-based real-time detection. Due to a limited rbcS sequence database, primers were designed and used to sequence this gene from 14 strains of Pseudo-nitzschia (including four P. multiseries) and 19 other marine diatoms. The IC-NASBA and qRT-PCR assays had a limit of detection of one cultured cell of P. multiseries and were linear over four and five orders of magnitude, respectively (r2 ! 0.98). Neither of the assays detected closely related organisms outside the Pseudo-nitzschia genus, and the qRT-PCR assay was specific to P. multiseries. While cross-reactivity of primers with unknown species prevented reliable detection of P. multiseries in spiked environmental samples using IC-NASBA, the qRT-PCR assay had positive detection from 107 cells/L to 103 cells/L. Nearly a 1:1 relationship was observed between predicted and calculated cell concentrations using qRT-PCR. Based on a diel expression study, the rbcS transcript copy number per cell ranged from 2.16 x 104 to 5.35 x 104, with the highest expression during early to mid photoperiod. The rbcS qRT-PCR assay is useful for the detection and enumeration of low concentrations of P. multiseries in the environment.
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Pyne, S. "Studies of microbial slime formation on toxic and non-toxic surfaces with special reference to diatom fouling of in-service vessels". Thesis, University of Portsmouth, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376461.
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Kon, Kam King Guillaume. "Revisiting Species Sensitivity Distribution : modelling species variability for the protection of communities". Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10194/document.
Testo completoAbstract (sommario):
La SSD (Species Sensitivity Distribution) est une méthode utilisée par les scientifiques et les régulateurs de tous les pays pour fixer la concentration sans danger de divers contaminants sources de stress pour l'environnement. Bien que fort répandue, cette approche souffre de diverses faiblesses sur le plan méthodologique, notamment parce qu'elle repose sur une utilisation partielle des données expérimentales. Cette thèse revisite la SSD actuelle en tentant de pallier ce défaut. Dans une première partie, nous présentons une méthodologie pour la prise en compte des données censurées dans la SSD et un outil web permettant d'appliquer cette méthode simplement. Dans une deuxième partie, nous proposons de modéliser l'ensemble de l'information présente dans les données expérimentales pour décrire la réponse d'une communauté exposée à un contaminant. A cet effet, nous développons une approche hiérarchique dans un paradigme bayésien. A partir d'un jeu de données décrivant l'effet de pesticides sur la croissance de diatomées, nous montrons l'intérêt de la méthode dans le cadre de l'appréciation des risques, de par sa prise en compte de la variabilité et de l'incertitude. Dans une troisième partie, nous proposons d'étendre cette approche hiérarchique pour la prise en compte de la dimension temporelle de la réponse. L'objectif de ce développement est d'affranchir autant que possible l'appréciation des risques de sa dépendance à la date de la dernière observation afin d'arriver à une description fine de son évolution et permettre une extrapolation. Cette approche est mise en œuvre à partir d'un modèle toxico-dynamique pour décrire des données d'effet de la salinité sur la survie d'espèces d'eau douceSpecies Sensitivity Distribution (SSD) is a method used by scientists and regulators from all over the world to determine the safe concentration for various contaminants stressing the environment. Although ubiquitous, this approach suffers from numerous methodological flaws, notably because it is based on incomplete use of experimental data. This thesis revisits classical SSD, attempting to overcome this shortcoming. First, we present a methodology to include censored data in SSD with a web-tool to apply it easily. Second, we propose to model all the information present in the experimental data to describe the response of a community exposed to a contaminant. To this aim, we develop a hierarchical model within a Bayesian framework. On a dataset describing the effect of pesticides on diatom growth, we illustrate how this method, accounting for variability as well as uncertainty, provides benefits to risk assessment. Third, we extend this hierarchical approach to include the temporal dimension of the community response. The objective of that development is to remove the dependence of risk assessment on the date of the last experimental observation in order to build a precise description of its time evolution and to extrapolate to longer times. This approach is build on a toxico-dynamic model and illustrated on a dataset describing the salinity tolerance of freshwater species
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Boissonneault, Katie Rose 1973. "Gene discovery and expression profiling in the toxin-producing marine diatom, Pseudo-nitzschia multiseries (Hasle) Hasle". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/39415.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, the Woods Hole Oceanographic Institution), 2004.Includes bibliographical references (leaves 169-180).
Toxic algae are a growing concern in the marine environment. One unique marine diatom, Pseudo-nitzschia multiseries (Hasle) Hasle, produces the neurotoxin domoic acid, which is the cause of amnesic shellfish poisoning. The molecular characterization of this organism has been limited to date. Therefore, the focus of this thesis was to identify and initiate characterization of actively expressed genes that control cell growth and physiology in P. multiseries, with the specific goal of identifying genes that may play a significant role in toxin production. The first step in gene discovery was to establish a complementary DNA (cDNA) library and a database of expressed sequence tags (ESTs) for P. multiseries. 2552 cDNAs were sequenced, generating a set of 1955 unique contigs, of which 21% demonstrated significant similarity with known protein coding sequences. Among the genes identified by sequence similarity were several involved in photosynthetic pathways, including fucoxanthin-chlorophyll a/c light harvesting protein and a C4-specific pyruvate, orthophosphate dikinase. Several genes that may be involved in domoic acid synthesis were also revealed through sequence similarity, for example, glutamate dehydrogenase and 5-oxo-L-prolinase. In addition, the identification of sequences that appear novel to Pseudo-nitzschia may provide insight into unique aspects of Pseudo-nitzschia biology, such as toxin production. Genes whose expression patterns were correlated with toxin production were identified by hybridization to a microarray manufactured from 5376 cDNAs. 121 cDNAs, representing 12 unique cDNA contigs or non-redundant cDNAs, showed significantly increased expression levels in P. multiseries cell populations that were actively producing toxin.
(cont.) The up-regulated transcripts included cDNAs with sequence similarity to 3-carboxymuconate cyclase, phosphoenolpyruvate carboxykinase, an amino acid transporter, a small heat shock protein, a long- chain fatty acid Co-A ligase, and an aldo/keto reductase. These results provide a framework for investigating the control of toxin production in P. multiseries. These transcripts may also be useful in ecological field studies in which they may serve as signatures of toxin production. Prospects for further application of molecular genetic technology to the understanding of the physiology and ecology of P. multiseries is discussed.
by Katie Rose Boissonneault.
Ph.D.
Libri sul tema "Toxic diatoms"
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Domoic Acid Workshop (1992 Oregon Institute of Marine Biology). Final report: Domoic Acid Workshop, Oregon Institute of Marine Biology, Feb. 21-23, 1992. [Corvallis, Or: Oregon Sea Grant, 1992.
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2
Pyne, Sean. Studies of microbial slime formation on toxic and non-toxic surfaces with special reference to diatom fouling of in-service vessels. Portsmouth: Portsmouth Polytechnic, School of Biological Sciences, 1987.
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3
Council for National Academic Awards (Great Britain), a cura di. Studies of microbial slime formation on toxic and non-toxic surfaces: With special reference to diatom fouling of in-service vessels. 1987.
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Kirchman, David L. Microbial primary production and phototrophy. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0006.
Testo completoAbstract (sommario):
This chapter is focused on the most important process in the biosphere, primary production, the turning of carbon dioxide into organic material by higher plants, algae, and cyanobacteria. Photosynthetic microbes account for roughly 50% of global primary production while the other half is by large, terrestrial plants. After reviewing the basic physiology of photosynthesis, the chapter discusses approaches to measuring gross and net primary production and how these processes affect fluxes of oxygen and carbon dioxide into and out of aquatic ecosystems. It then points out that terrestrial plants have high biomass but relatively low growth, while the opposite is the case for aquatic algae and cyanobacteria. Primary production varies greatly with the seasons in temperate ecosystems, punctuated by the spring bloom when the biomass of one algal type, diatoms, reaches a maximum. Other abundant algal types include coccolithophorids in the oceans and filamentous cyanobacteria in freshwaters. After the bloom, small algae take over and out-compete larger forms for limiting nutrients because of superior uptake kinetics. Abundant types of small algae include two coccoid cyanobacteria, Synechococcus and Prochlorococcus, the latter said to be the most abundant photoautotroph on the planet because of its large numbers in oligotrophic oceans. Other algae, often dinoflagellates, are toxic. Many algae can also graze on other microbes, probably to obtain limiting nitrogen or phosphorus. Still other microbes are mainly heterotrophic but are capable of harvesting light energy. Primary production in oxic environments is carried out by oxygenic photosynthetic organisms, whereas in anoxic environments with sufficient light, it is anaerobic anoxygenic photosynthesis in which oxygen is not produced. Although its contribution to global primary production is small, anoxygenic photosynthesis helps us understand the biophysics and biochemistry of photosynthesis and its evolution on early Earth. These microbes as well as aerobic phototrophic and heterotrophic microbes make up microbial mats. These mats can provide insights into early life on the planet when a type of mat, “stromatolites,” covered vast areas of primordial seas in the Proterozoic.
Capitoli di libri sul tema "Toxic diatoms"
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Horner, Rita A. "Toxic diatoms: report on a workshop". In Twelfth International Diatom Symposium, 527. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3622-0_54.
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Villac, Maria Célia, e Irena Kaczmarska. "Marine Planktonic Diatoms, Including Potentially Toxic Species". In The Diatom World, 465–90. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1327-7_21.
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Horner, Rita A., e James R. Postel. "Toxic diatoms in western Washington waters (U.S. west coast)". In Twelfth International Diatom Symposium, 197–205. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-3622-0_21.
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Sezgin, Rabia, Ugur Atakli e Muharrem Balci. "The Ecological Role of Phytoplankton and the Drivers of Harmful Algal Blooms: Responses to Climate-Induced Stressors in Marine Ecosystems". In Ecological Dynamics in the Face of Climate Change, 75–88. Istanbul: Nobel Tip Kitabevleri, 2024. http://dx.doi.org/10.69860/nobel.9786053359258.5.
Testo completoAbstract (sommario):
Phytoplankton, a group of single-celled organisms capable of photosynthesis, are vital to marine ecosystems due to their primary production and role in biogeochemical cycles. They adapt to diverse environments and utilize complex nutritional strategies. Phytoplankton contribute to the global carbon cycle through carbon fixation and sequestration, particularly by diatoms and coccolithophores. However, climate change and anthropogenic impacts are altering their dynamics, with rising temperatures, acidification, and pollution affecting growth, productivity, and community structure. Harmful algal blooms (HABs), driven by eutrophication and increased nutrient loads, pose significant threats to marine ecosystems, causing toxic effects and disrupting food webs. Effective management of these issues requires extensive research, international cooperation, and informed policy measures. Understanding phytoplankton’s responses to environmental changes is crucial for predicting marine ecosystem futures and developing strategies to mitigate the adverse effects of climate change and pollution.
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Bargu, Sibel, Emily Smith e Koray Ozhan. "Toxic Diatom Pseudo-nitzschia and Its Primary Consumers (Vectors)". In The Diatom World, 491–512. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1327-7_22.
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Lincoln, Jean A., Jefferson T. Turner, Stephen S. Bates, Claude Léger e David A. Gauthier. "Feeding, egg production, and egg hatching success of the copepods Acartia tonsa and Temora longicornis on diets of the toxic diatom Pseudo-nitzschia multiseries and the non-toxic diatom Pseudo-nitzschia pungens". In Copepoda: Developments in Ecology, Biology and Systematics, 107–20. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/0-306-47537-5_9.
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Nichols, Gordon. "Human health risks from toxic cyanobacteria, dinoflagellates and diatoms". In Environmental Medicine, 384–87. CRC Press, 2010. http://dx.doi.org/10.1201/b13390-43.
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Emília Cunha, Maria, Hugo Quental Ferreira, Ana Barradas e Pedro Pousão-Ferreira. "Response of Marine Plankton Communities in Ponds to the Presence of Vertical Structures". In Plankton Communities [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97475.
Testo completoAbstract (sommario):
The effects of bottom vertical structures like AquaMats® in enhancing plankton productivity was evaluated. One experimental earthen pond of 500 m2 was provided with AquaMats® increasing the surface substrate area 12 times and water quality, phytoplankton and zooplankton populations developed during almost 100 days was compared with a pond without AquaMats®. Their presence favored the development of Dinoflagellates (Miozoa, Dinophyceae), mostly Gymnodiniales, which may be of some concern since some species of this group have been associated with toxic algal blooms while in the ponds without AquaMats® Diatoms (Bacillariophyta) predominate. In both ponds plankton production was very much sculptured by external nutrients added to the systems. The balance between different nutrients is extremely important to regulate the phytoplankton populations with Diatoms blooming at silicate concentrations higher than 2 μM and below this level and at low nitrate and high ammonium being more appropriate for Dinoflagellates. The linkage between phytoplankton and zooplankton population in ponds is strong with zooplankton exerting control over the phytoplankton population and vice-versa. The use of vertical substrates enhances plankton productivity by increasing the substrate area for periphyton fixation. The main zooplankton taxonomic groups associated with the presence of AquaMats® were Calanoid and Harpacticoid copepodites and nauplii, veligers of gastropods and trochophore of polychaets, larval stages of organisms that except for calanoid copepods are benthic and correspond to the meroplanktonic phase in the life cycle of those organisms.
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"Ecobiology of Amnesic Shellfish Toxin Producing Diatoms". In Seafood and Freshwater Toxins, 401–14. CRC Press, 2008. http://dx.doi.org/10.1201/9781420007541-32.
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Kotaki, Yuichi. "Ecobiology of Amnesic Shellfish Toxin Producing Diatoms". In Seafood and Freshwater Toxins, 383–96. CRC Press, 2008. http://dx.doi.org/10.1201/9781420007541.ch19.
Testo completoAtti di convegni sul tema "Toxic diatoms"
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Soeprobowati, Tri Retnaningsih, Riche Hariyati, Jumari Jumari, Geyga Pamrayoga e Henk Heijnis. "The minimum number of valvae diatoms identified for water quality monitoring of lake Balekambang, Dieng Central Java". In THE 6TH INTERNATIONAL CONFERENCE ON ENERGY, ENVIRONMENT, EPIDEMIOLOGY AND INFORMATION SYSTEM (ICENIS) 2021: Topic of Energy, Environment, Epidemiology, and Information System. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0125027.
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