79 resultados para Branchiopoda
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The author describes an investigation, the primary aims of which were to locate accurately and assess the ecological status of two Eurycercus glacialis populations in Scotland. A 1957 record of the species did not give a precise location, and on publication of a preliminary report on the location, the possibility of a second location was suggested. In April and May 1988, 16 waterbodies were sampled near Tain, in Scotland, as a result of which the dune waterbodies at Morrich More have now been positively identified as the only known location of E. glacialis in mainland Britain. A second population was found on Shetland. As the mainland site is under considerable developmental pressure from oil pipeline construction, the importance of determining the extent of the distribution on Shetland is highlighted.
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Two new clam shrimp species belonging to the genera Eulimnadia Packard, 1874 and Leptestheria Sars 1898 from Kerala, India are described. Spinicaudatan clam shrimp are among the least studied groups in India, with only 30 species reported. Eulimnadia azisi sp. nov. was collected from rain fed, temporary, rocky depressions at Vettilapara, in Western Ghats, Kerala. No males were observed and the population may be hermaphroditic. Leptestheria dumonti sp. nov. was collected from the paddy fields at Parapukara, Kerala. Altogether two species of Leptestheria and nine species of Eulimnadia have been reported from India, and this is the first report of the genus Leptestheria from Kerala.
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This study focused the spatial and temporal distribution of the composition, abundance, and diversity of planktonic cladocerans from eutrophic, Iraí Reservoir, as well as their relationships with some biotic and abiotic variables. The tested hypothesis was that cladocerans present higher variation in a temporal than in a spatial scale. The samples were taken monthly in 6 stations, from March/02 to July/03. Twenty-four taxa were identified, distributed in 7 families, the richest families being Daphniidae (6 spp.), Chydoridae (6 spp.), and Bosminidae (5 spp.). The most frequent and abundant species were Bosmina hagmanni, Moina minuta, and Ceriodaphnia cornuta. The highest abundances were found in September/2002. Temporally, rainfall influenced organism's distribution, while spatially cladocerans were more affected by reservoir hydrodynamics and wind action. The low species richness could be a reflection of the trophic state of the reservoir, in which a dominance of Cyanobacteria was observed during that study period. Both scales showed high variation, but only the temporal scale showed significant difference to richness and abundance. Nearby the end of this study, higher stable values of species richness were recorded, which could suggest an increase in the water quality due to des-pollutions actions.
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Experimentos foram desenvolvidos para estudar as taxas de alimentação e de sobrevivência de Artemia salina alimentada com cepas não tóxicas do dinoflagelado Gyrodinium corsicum e da Chryptophyta Rhodomonas baltica. As taxas de filtração sobre R. baltica e G. corsicum variaram entre 3,35 e 7,14 ml.artemia-1.h-1 e 2,97 e 15,86 ml.artemia-1.h-, respectivamente. As taxas de ingestão observadas para A. salina não indicaram disfunção digestiva ou prejuízo fisiológico nos organismos alimentados com G. corsicum, sendo a resposta funcional destes organismos similar a observada em copépodos alimentados com diferentes concentrações de alimento. As taxas de mortalidade de A. salina oscilaram entre 2,5 e 100% quando alimentada com R. baltica e G. corsicum, respectivamente. As maiores taxas de mortalidade observadas para os organismos alimentados com G. corsicum indicam que este dinoflagelado apresenta algum efeito nocivo sobre A. salina, embora não tenha sido possível confirmar se sua origem está relacionada com a produção de toxinas ou com a inadequação nutritiva deste dinoflagelado para alimentação de organismos desta espécie.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Background: Eicosanoids are biologically active, oxygenated metabolites of three C20 polyunsaturated fatty acids. They act as signalling molecules within the autocrine or paracrine system in both vertebrates and invertebrates mainly functioning as important mediators in reproduction, the immune system and ion transport. The biosynthesis of eicosanoids has been intensively studied in mammals and it is known that they are synthesised from the fatty acid, arachidonic acid, through either the cyclooxygenase (COX) pathway; the lipoxygenase (LOX) pathway; or the cytochrome P450 epoxygenase pathway. However, little is still known about the synthesis and structure of the pathway in invertebrates. Results: Here, we show transcriptomic evidence from Daphnia magna (Crustacea: Branchiopoda) together with a bioinformatic analysis of the D. pulex genome providing insight on the role of eicosanoids in these crustaceans as well as outlining a putative pathway of eicosanoid biosynthesis. Daphnia appear only to have one copy of the gene encoding the key enzyme COX, and phylogenetic analysis reveals that the predicted protein sequence of Daphnia COX clusters with other invertebrates. There is no current evidence of an epoxygenase pathway in Daphnia; however, LOX products are most certainly synthesised in daphnids. Conclusion: We have outlined the structure of eicosanoid biosynthesis in Daphnia, a key genus in freshwater ecosystems. Improved knowledge of the function and synthesis of eicosanoids in Daphnia and other invertebrates could have important implications for several areas within ecology. This provisional overview of daphnid eicosanoid biosynthesis provides a guide on where to focus future research activities in this area.