Temporal variation of lagoon-associated and pelagic (open ocean) planktonic 18S rRNA-gene sequences (Mo’orea, French Polynesia).
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PROVIDER: PRJEB69515 | ENA |
REPOSITORIES: ENA
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Project description:Planktonic 16S rRNA gene sequences (V4/V5 region) from water samples collected inside the northern coral-reef lagoon of Mo’orea (French Polynesia) and 4 km offshore, in the tropical open ocean.
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Project description:We examined gene expression profiling of native mussels that were sampled in early summer 2003 from sites of the Venice lagoon area known to be differently affected by chemical pollution: Sites 1 and 2 close to the industrial district of Marghera and Site 3 close to the Lido lagoon outlet. Site 4, a current mussel farm located offshore, has been chosen as source of reference targets for microarray hybridizations. We have limited the preliminary assessment to the digestive gland. Digestive gland total RNA of each Site was hybridized in competition with the offshore mussels (Site 4 - Reference) and the relative abundance of each gene was measured by directly comparing fluorescent signals for each probe. We carried out two separate hybridizations for each site of the Venice lagoon area.. Keywords = digestive gland Keywords = Venice lagoon Keywords = chemical pollution Keywords = native mussels Keywords = transcriptional profiling Keywords: ordered
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Project description:Planktonic 18S rRNA gene sequences (V4 region) from water samples collected around an Acropora pulchra colony (Tema’e Beach reef, Mo’orea)
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Project description:Diuron is a herbicide commonly used in agricultural areas where excess application causes it to leach into rivers, reach sensitive marine environments like the Great Barrier Reef (GBR) lagoon and pose risks to marine life. To investigate the impact of diuron on whole prokaryotic communities that underpin the marine food web and are integral to coral reef health, GBR lagoon water was incubated with diuron at environmentally-relevant concentration (8 µg/L), and sequenced at specific time points over the following year. 16S rRNA gene amplicon profiling revealed no significant short- or long-term effect of diuron on microbiome structure. The relative abundance of prokaryotic phototrophs was not significantly altered by diuron, which suggests that they were largely tolerant at this concentration. Assembly of a metagenome derived from waters sampled at a similar location in the GBR lagoon did not reveal the presence of mutations in the cyanobacterial photosystem that could explain diuron tolerance. However, resident phages displayed several variants of this gene and could potentially play a role in tolerance acquisition. Slow biodegradation of diuron was reported in the incubation flasks, but no correlation with the relative abundance of heterotrophs was evident. Analysis of metagenomic reads supports the hypothesis that previously uncharacterized hydrolases carried by low-abundance species may mediate herbicide degradation in the GBR lagoon. Overall, this study offers evidence that pelagic phototrophs of the GBR lagoon may be more tolerant of diuron than other tropical organisms, and that heterotrophs in the microbial seed bank may have the potential to degrade diuron and alleviate local anthropogenic stresses to inshore GBR ecosystems.
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Project description:The species-rich diatom family Chaetocerotaceae is common in the coastal marine phytoplankton worldwide where it is responsible for a substantial part of the primary production. Despite its relevance for the global cycling of carbon and silica, many species are still described only morphologically, and numerous specimens do not fit any described taxa. Nowadays, studies to assess plankton biodiversity deploy high throughput sequencing metabarcoding of the 18S rDNA V4 region, but to translate the gathered metabarcodes into biologically meaningful taxa, there is a need for reference barcodes. However, 18S reference barcodes for this important family are still relatively scarce. We provide 18S rDNA and partial 28S rDNA reference sequences of 443 morphologically characterized chaetocerotacean strains. We gathered 164 of the 216 18S sequences and 244 of the 413 28S sequences of strains from the Gulf of Naples, Atlantic France, and Chile. Inferred phylogenies showed 84 terminal taxa in seven principal clades. Two of these clades included terminal taxa whose rDNA sequences contained spliceosomal and Group IC1 introns. Regarding the commonly used metabarcode markers in planktonic diversity studies, all terminal taxa can be discriminated with the 18S V4 hypervariable region; its primers fit their targets in all but two species, and the V4-tree topology is similar to that of the 18S. Hence V4-metabarcodes of unknown Chaetocerotaceae are assignable to the family. Regarding the V9 hypervariable region, most terminal taxa can be discriminated, but several contain introns in their primer targets. Moreover, poor phylogenetic resolution of the V9 region affects placement of metabarcodes of putative but unknown chaetocerotacean taxa, and hence, uncertainty in taxonomic assignment, even of higher taxa.
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