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Xin Shen - One of the best experts on this subject based on the ideXlab platform.
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the complete mitochondrial genome sequence of euphausia pacifica malacostraca Euphausiacea reveals a novel gene order and unusual tandem repeats
Genome, 2011Co-Authors: Xin Shen, Haiqing Wang, Minxiao WangAbstract:Euphausiid krill are dominant organisms in the zooplankton population and play a central role in marine ecosystems. Euphausia pacifica (Malacostraca: Euphausiacea) is one of the most important and dominant crustaceans in the North Pacific Ocean. In this paper, we described the gene content, organization, and codon usage of the E. pacifica mitochondrial genome. The mitochondrial genome of E. pacifica is 16 898 bp in length and contains a standard set of 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. Trans location of three transfer RNAs (trnL(1), trnL(2), and trnW) was found in the E. pacifica mitochondrial genome when comparing with the pancrustacean ground pattern. The rate of K(a)/K(s), in 13 protein-coding genes among three krill is much less than 1, which indicates a strong purifying selection within this group. The largest noncoding region in the E. pacifica mitochondrial genome contains one section with tandem repeats (4.7 x 154 bp), which are the largest tandem repeats found in malacostracan mitochondrial genomes so far. All analyses based on nucleotide and amino acid data strongly support the monophyly of Stomatopoda, Penacidae, Caridea, Brachyura, and Euphausiacea. The Bayesian analysis of nucleotide and amino acid datasets strongly supports the close relationship between Euphausiacea and Decapoda, which confirms traditional findings. The maximum likelihood analysis based on amino acid data strongly supports the close relationship between Euphausiacea and Penaeidae, which destroys the monophyly of Decapoda.
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the mitochondrial genome of euphausia superba prydz bay crustacea malacostraca Euphausiacea reveals a novel gene arrangement and potential molecular markers
Molecular Biology Reports, 2010Co-Authors: Xin Shen, Haiqing Wang, Mei Tian, Minxiao WangAbstract:Euphausiid krill are dominant organisms in the zooplankton population and play a central role in marine ecosystems. In this paper, we described the gene organization, gene rearrangement and codon usage in the mitochondrial genome of Euphausia superba Dana 1852 (sampling from Prydz Bay, PB). The mitochondrial genome of E. superba is more than 15,498 bp in length (partial non-coding region was not determined). Translocation of four tRNAs (trnL1, trnL2, trnW and trnI) and duplication of one tRNA (trnN) were founded in the mitochondrial genome of E. superba when comparing its genome with the pancrustacean ground pattern. To investigate the phylogenetic relationship within Malacostraca, phylogenetic trees based on currently available malacostracan mitochondrial genomes were built with the maximum likelihood and the Bayesian models. All analyses based on nucleotide and amino acid data strongly support the monophyly of Stomatopoda, Penaeidae, Caridea, and Brachyura, which is consistent with previous research. However, the taxonomic position of Euphausiacea within Malacostraca is unstable. From comparing the mitochondrial genome between E. superba (PB) and E. superba (sampling from Weddell Sea, WS), we found that nad2 gene contains maximal variation with 61 segregating sites, following by nad5 gene which has 12 segregating sites. Thus, nad2 and nad5 genes may be used as potential molecular markers to study the inherit diversity among different E. superba groups, which would be helpful to the exploitation and management of E. superba resources.
Minxiao Wang - One of the best experts on this subject based on the ideXlab platform.
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the complete mitochondrial genome sequence of euphausia pacifica malacostraca Euphausiacea reveals a novel gene order and unusual tandem repeats
Genome, 2011Co-Authors: Xin Shen, Haiqing Wang, Minxiao WangAbstract:Euphausiid krill are dominant organisms in the zooplankton population and play a central role in marine ecosystems. Euphausia pacifica (Malacostraca: Euphausiacea) is one of the most important and dominant crustaceans in the North Pacific Ocean. In this paper, we described the gene content, organization, and codon usage of the E. pacifica mitochondrial genome. The mitochondrial genome of E. pacifica is 16 898 bp in length and contains a standard set of 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. Trans location of three transfer RNAs (trnL(1), trnL(2), and trnW) was found in the E. pacifica mitochondrial genome when comparing with the pancrustacean ground pattern. The rate of K(a)/K(s), in 13 protein-coding genes among three krill is much less than 1, which indicates a strong purifying selection within this group. The largest noncoding region in the E. pacifica mitochondrial genome contains one section with tandem repeats (4.7 x 154 bp), which are the largest tandem repeats found in malacostracan mitochondrial genomes so far. All analyses based on nucleotide and amino acid data strongly support the monophyly of Stomatopoda, Penacidae, Caridea, Brachyura, and Euphausiacea. The Bayesian analysis of nucleotide and amino acid datasets strongly supports the close relationship between Euphausiacea and Decapoda, which confirms traditional findings. The maximum likelihood analysis based on amino acid data strongly supports the close relationship between Euphausiacea and Penaeidae, which destroys the monophyly of Decapoda.
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the mitochondrial genome of euphausia superba prydz bay crustacea malacostraca Euphausiacea reveals a novel gene arrangement and potential molecular markers
Molecular Biology Reports, 2010Co-Authors: Xin Shen, Haiqing Wang, Mei Tian, Minxiao WangAbstract:Euphausiid krill are dominant organisms in the zooplankton population and play a central role in marine ecosystems. In this paper, we described the gene organization, gene rearrangement and codon usage in the mitochondrial genome of Euphausia superba Dana 1852 (sampling from Prydz Bay, PB). The mitochondrial genome of E. superba is more than 15,498 bp in length (partial non-coding region was not determined). Translocation of four tRNAs (trnL1, trnL2, trnW and trnI) and duplication of one tRNA (trnN) were founded in the mitochondrial genome of E. superba when comparing its genome with the pancrustacean ground pattern. To investigate the phylogenetic relationship within Malacostraca, phylogenetic trees based on currently available malacostracan mitochondrial genomes were built with the maximum likelihood and the Bayesian models. All analyses based on nucleotide and amino acid data strongly support the monophyly of Stomatopoda, Penaeidae, Caridea, and Brachyura, which is consistent with previous research. However, the taxonomic position of Euphausiacea within Malacostraca is unstable. From comparing the mitochondrial genome between E. superba (PB) and E. superba (sampling from Weddell Sea, WS), we found that nad2 gene contains maximal variation with 61 segregating sites, following by nad5 gene which has 12 segregating sites. Thus, nad2 and nad5 genes may be used as potential molecular markers to study the inherit diversity among different E. superba groups, which would be helpful to the exploitation and management of E. superba resources.
Dieter Waloszek - One of the best experts on this subject based on the ideXlab platform.
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larval development of euphausia superba dana 1852 and a phylogenetic analysis of the Euphausiacea
Hydrobiologia, 2001Co-Authors: Andreas Maas, Dieter WaloszekAbstract:Literature data and new investigations by SEM of selected ontogenetic stages of the Antarctic Krill, Euphausia superba Dana, 1852 revealed morphological characters that are either missing in, or significantly changed towards, the adult. Besides adult features, such ontogenetic characters enabled us to propose a hypothesis of the phylogenetic relationships of and within the Euphausiacea on the basis of a computer aided cladistic analysis. These are of the form (Bentheuphausia amblyops + Euphausiidae = ('Thysanopoda' + Nematobrachion + Euphausiinae = (Meganyctiphanes norvegica + Euphausiini, new name + Nematoscelini, new name = (Nyctiphanes + Nematoscelina, new name)))). From this analysis the taxon names 'Euphausiina', 'Nematoscelini', and 'Nematoscelina' are introduced for in-groups of the taxon Euphausiacea as representing monophyletic units. The position of a set of ontogenetic characters remains relatively uncertain due to the still unknown larval development of Bentheuphausia amblyops (G. O. Sars, 1883).
Galina B Rudneva - One of the best experts on this subject based on the ideXlab platform.
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winter distribution of euphausiids Euphausiacea in the barents sea 2000 2005
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Natalia G Zhukova, V N Nesterova, Irina Prokopchuk, Galina B RudnevaAbstract:Abstract The purpose of the study is to analyze the state of the Barents Sea euphausiids populations in the warm period (2000–2005) based on the study of their structure dynamics and distribution under the influence of abiotic and biotic factors. For estimation of their aggregations in the bottom layer, the traditional method was used with the help of the modified egg net (0.2 m2 opening area, 564 μm mesh size). The net is used for collecting euphausiids in the autumn–winter period when their activity is reduced, which results in high-catch efficiency. The findings confirmed the major formation patterns of the euphausiids species composition associated with climate change in the Arctic basin. As before, in the warm years, one can see a clear-cut differentiation of space distribution of the dominant euphausiids Thysanoessa genus with localization of the more thermophilic Thysanoessa inermis in the north-west Barents Sea and Thysanoessa raschii in the east. The major euphausiids aggregations are formed of these species. In 2004, the first data of euphausiids distribution in the northern Barents Sea (77–79°N) were obtained, and demonstrated extremely high concentrations of T. inermis in this area, with the biomass as high as 1.7–2.4 g m−2 in terms of dry weight. These data have improved our knowledge of the distribution and euphausiids abundance during periods of elevated sea-water temperatures in the Barents Sea. The oceanic Atlantic species were found to increase in abundance due to elevated advection to the Barents Sea during the study period. Thus, after nearly a 30-year-long absence of the moderate subtropical Nematoscelis megalops in the Barents Sea, they were found again in 2003–2005. However in comparison with 1960, the north-east border of its distribution considerably shifted to 73°50′N 50°22′E. The portion of Meganyctiphanes norvegica also varied considerably—from 10% to 20% of the total euphausiids population in the warm 1950s–1960s almost to complete disappearing in 1970–1990s. The peak of this species’ occurrence (18–26%) took place in the beginning of warm period (1999–2000) after a succession of cold years. The subsequent reduction of the relative abundance of M. norvegica to 7% might have been mostly caused by fish predation during a period of low population densities of capelin. This high predation pressure may therefore have been mediated both by other pelagic fishes (i.e. herring, blue whiting, polar cod) but also by demersal fishes such as cod and haddock. Similar sharp fluctuations in the capelin stock (the major consumer of euphausiids) created marked perturbations in the food web in the Barents Sea in the middle 1980s and the early 1990s.
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Winter distribution of euphausiids (Euphausiacea) in the Barents Sea (2000–2005)
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Natalia G Zhukova, V N Nesterova, Irina Prokopchuk, Galina B RudnevaAbstract:Abstract The purpose of the study is to analyze the state of the Barents Sea euphausiids populations in the warm period (2000–2005) based on the study of their structure dynamics and distribution under the influence of abiotic and biotic factors. For estimation of their aggregations in the bottom layer, the traditional method was used with the help of the modified egg net (0.2 m2 opening area, 564 μm mesh size). The net is used for collecting euphausiids in the autumn–winter period when their activity is reduced, which results in high-catch efficiency. The findings confirmed the major formation patterns of the euphausiids species composition associated with climate change in the Arctic basin. As before, in the warm years, one can see a clear-cut differentiation of space distribution of the dominant euphausiids Thysanoessa genus with localization of the more thermophilic Thysanoessa inermis in the north-west Barents Sea and Thysanoessa raschii in the east. The major euphausiids aggregations are formed of these species. In 2004, the first data of euphausiids distribution in the northern Barents Sea (77–79°N) were obtained, and demonstrated extremely high concentrations of T. inermis in this area, with the biomass as high as 1.7–2.4 g m−2 in terms of dry weight. These data have improved our knowledge of the distribution and euphausiids abundance during periods of elevated sea-water temperatures in the Barents Sea. The oceanic Atlantic species were found to increase in abundance due to elevated advection to the Barents Sea during the study period. Thus, after nearly a 30-year-long absence of the moderate subtropical Nematoscelis megalops in the Barents Sea, they were found again in 2003–2005. However in comparison with 1960, the north-east border of its distribution considerably shifted to 73°50′N 50°22′E. The portion of Meganyctiphanes norvegica also varied considerably—from 10% to 20% of the total euphausiids population in the warm 1950s–1960s almost to complete disappearing in 1970–1990s. The peak of this species’ occurrence (18–26%) took place in the beginning of warm period (1999–2000) after a succession of cold years. The subsequent reduction of the relative abundance of M. norvegica to 7% might have been mostly caused by fish predation during a period of low population densities of capelin. This high predation pressure may therefore have been mediated both by other pelagic fishes (i.e. herring, blue whiting, polar cod) but also by demersal fishes such as cod and haddock. Similar sharp fluctuations in the capelin stock (the major consumer of euphausiids) created marked perturbations in the food web in the Barents Sea in the middle 1980s and the early 1990s.
Carolyn W. Burns - One of the best experts on this subject based on the ideXlab platform.
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feeding response of nyctiphanes australis Euphausiacea to various nanoplankton sizes and taxa
Marine Ecology Progress Series, 2003Co-Authors: Graeme J Haywood, Carolyn W. BurnsAbstract:Nanoplankton (2 to 20 µm) are a substantial fraction of the plankton in the sea, where they form a potential food source for zooplankton. Monocultures of 12 nanoplankton taxa of different cell size and 1 species of Thalassiosira (microplankton) were offered to Nyctiphanes australis to determine whether they would be consumed and, if so, determine rates of clearance and ingestion by the euphausiid. N. australis ingested very small cells (3.5 to 5.4 µm equivalent spherical diameter) at rates ≤ 5 × 10 5 cells h -1 . A total of 8 nanoplankton taxa were consumed at rates that provided N. aus- tralis with its minimum food requirement of 2% body carbon d -1 , and so could maintain it when microplankton abundance is low. Our results suggest that N. australis can detect and avoid unpalat- able food such as the chlorophytes Dunaliella and Nannochloris, but is susceptible to the toxic dinoflagellate Alexandrium minutum.
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growth of nyctiphanes Euphausiacea on different diets
Journal of Experimental Marine Biology and Ecology, 2003Co-Authors: G.j Haywood, Carolyn W. BurnsAbstract:To determine the effects of diet on the growth rate of Nyctiphanes australis (Euphausiacea), metanauplii were reared to mature adults in the laboratory. Sibships (siblings from the same mother) were raised on different food items collected from the field and cultured in the laboratory. A sibship was divided at the calyptopis stage and 50% of the siblings were fed one of three experimental diets (Thalassiosira, Heterocapsa, or Phaeocystis); the balance of the siblings were fed a control diet of Tetraselmis chuii and Artemia larvae. The growth rate of siblings was not altered by the different diets. Siblings developed asynchronously, however, from egg to adult. Some animals were always at a more advanced developmental phase and by day 100, up to 25% larger than their siblings (p<0.001). A possible implication of this result is that the larval growth of N. australis is strongly influenced by genotype.
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Growth of Nyctiphanes (Euphausiacea) on different diets
Journal of Experimental Marine Biology and Ecology, 2003Co-Authors: G.j Haywood, Carolyn W. BurnsAbstract:To determine the effects of diet on the growth rate of Nyctiphanes australis (Euphausiacea), metanauplii were reared to mature adults in the laboratory. Sibships (siblings from the same mother) were raised on different food items collected from the field and cultured in the laboratory. A sibship was divided at the calyptopis stage and 50% of the siblings were fed one of three experimental diets (Thalassiosira, Heterocapsa, or Phaeocystis); the balance of the siblings were fed a control diet of Tetraselmis chuii and Artemia larvae. The growth rate of siblings was not altered by the different diets. Siblings developed asynchronously, however, from egg to adult. Some animals were always at a more advanced developmental phase and by day 100, up to 25% larger than their siblings (p
