Project description:EMG produced TPA metagenomics assembly of the Core genomes of cosmopolitan surface ocean plankton (jcvi_gos_circumnavigation) data set
Project description:The diversity and environmental distribution of the nosZ gene, which encodes the enzyme responsible for the consumption of nitrous oxide, was investigated in marine and terrestrial environments using a functional gene microarray. The microbial communities represented by the nosZ gene probes showed strong biogeographical separation, with communities from surface ocean waters and agricultural soils significantly different from each other and from those in oceanic oxygen minimum zones. Atypical nosZ genes, usually associated with incomplete denitrification pathways, were detected in all the environments, including surface ocean waters. The abundance of nosZ genes, as estimated by quantitative PCR, was highest in the agricultural soils and lowest in surface ocean waters.
2018-10-19 | GSE121473 | GEO
Project description:A high-speed plankton net: expanding global collection of surface ocean data
Project description:In this study we applied MASC-seq (massive and parallel microarray sequencing, https://doi.org/10.1038/ncomms13182), a scRNA-seq method that facilitates sequencing of thousands of cells in parallel, and that couples microscope images with the single cell transcriptome data. For this method, fixed cells are spread over a microarray with 100 μm-sized spots of DNA capture probes with spot-specific indices. The cells are first imaged using a scanning microscope and then permeabilized, releasing their RNA out of the cells and bind to the probes on the array. cDNA is synthesized, harvested and sequenced, and, using the spot-specific barcode-sequences, cDNA sequences stemming from a specific spot (i.e., cell) can be linked to the microscope image of the corresponding cell. However, until now, the MASC-seq method has only been applied to mammalian cells. The aim of this study was to test and adapt the MASC-seq method for application on unicellular eukaryotic plankton. We applied and optimized the method on three cultured plankton representatives, abundant in communities of aquatic environments, Phaeodactylum tricornutum (a diatom, silica and polysaccharide cell walls 23), Heterocapsa sp. (a dinoflagellate, cellulose thecal plates 24) and Tetrahymena thermophila (a ciliate, lipid membrane 25) which all have different size and diverse cell surface structures common to plankton. We optimized several steps in the protocol to make it more suitable for planktonic cells and compared the results from MASC-seq generated single cell transcriptomes to bulk RNA sequencing.
Project description:Marine microbial communities are critical for biogeochemical cycles and the productivity of ocean ecosystems. Primary productivity, at the base of marine food webs, is constrained by nutrient availability in the surface ocean, and nutrient advection from deeper waters can fuel photosynthesis. In this study, we compared the transcriptional responses by surface microbial communities after experimental deep water mixing to the transcriptional patterns of in situ microbial communities collected with high-resolution automated sampling during a bloom in the North Pacific Subtropical Gyre. Transcriptional responses were assayed with the MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories) marine environmental microarray, which targets all three domains of life and viruses. The experiments showed that mixing of deep and surface waters substantially affects the transcription of photosystem and nutrient response genes among photosynthetic taxa within 24 hours, and that there are specific responses associated with the addition of deep water containing particles (organisms and detritus) compared to filtered deep water. In situ gene transcription was most similar to that in surface water experiments with deep water additions, showing that in situ populations were affected by mixing of nutrients at the six sampling sites. Together, these results show the value of targeted metatranscriptomes for assessing the physiological status of complex microbial communities.
Project description:The fraction of dissolved dimethylsulfoniopropionate (DMSPd) converted by marine bacterioplankton into the climate-active gas dimethylsulfide (DMS) varies widely in the ocean, with the factors that determine this value still largely unknown. One current hypothesis is that the ratio of DMS formation:DMSP demethylation is determined by DMSP availability, with 'availability' in both an absolute sense (i.e., concentration in seawater) and in a relative sense (i.e., proportionally to other labile organic S compounds) being proposed as the critical factor. We investigated these models during an experimentally-induced phytoplankton bloom using an environmental microarray targeting DMSP-related gene expression in the Roseobacter group, a taxon of marine bacteria known to play an important role in the surface ocean sulfur cycle. The array consisted of 1,578 probes to 431 genes, including those previously linked to DMSP degradation as well as core genes common in sequenced Roseobacter genomes. The prevailing pattern of Roseobacter gene expression showed depletion of DMSP-related transcripts during the peak of the bloom, despite the fact that absolute concentrations and flux of DMSP-related compounds were increasing. A likely interpretation is that DMSPd was assimilated by Roseobacter populations in proportion to its relative abundance in the organic matter pool (the “relative sense” hypothesis), and that it is not taken up in preference to other sources of labile organic sulfur or carbon produced during the bloom. The relative investment of the Roseobacter community in DMSP demethylation did not predict the fractional conversion of DMSP to DMS, however, suggesting a complex regulatory process that may involve multiple fates of DMSPd.
Project description:Analysis of microbial gene expression in response to physical and chemical gradients forming in the Columbia River, estuary, plume and coastal ocean was done in the context of the environmental data base. Gene expression was analyzed for 2,234 individual genes that were selected from fully sequenced genomes of 246 prokaryotic species (bacteria and archaea) as related to the nitrogen metabolism and carbon fixation. Seasonal molecular portraits of differential gene expression in prokaryotic communities during river-to-ocean transition were created using freshwater baseline samples (268, 270, 347, 002, 006, 207, 212).