Project description:A functional gene microarray was developed and used to investigate phytoplankton community composition and gene expression in the English Channel. Genes encoding the CO2 fixation enzyme RuBisCO (rbcL) and the nitrate assimilation enzyme nitrate reductase (NR) representing several major groups of phytoplankton were included as oligonucleotide probes on the 'phytoarray'. Five major groups of eukaryotic phytoplankton that possess the Type 1D rbcL gene were detected, both in terms of presence (DNA) and activity (rbcL gene expression). Changes in relative signal intensity among the Type 1D rbcL probes indicated a shift from diatom dominance in the spring bloom to dominance by haptophytes and flagellates later in the summer. Because of the limitations of a smaller database, NR probes detected fewer groups, but due to the greater diversity among known NR sequences, NR probes provided higher phylogenetic resolution than did rbcL probes, and identified two uncultivated diatom phylotypes as the most abundant (DNA) and active (NR gene expression) in field samples. Unidentified chlorophytes and the diatom Phaeodactylum tricornutum were detected at both the DNA and cDNA (gene expression) levels. The reproducibility of the array was evaluated in several ways and future directions for further improvement of probe development and sensitivity are outlined. The phytoarray provides a relatively high resolution, high throughput approach to assessing phytoplankton community composition in marine environments. Keywords: seawater natural assemblages, functional gene expression Two functional genes, nitrate reductase and RuBisCO, 4 - 8 replicate features per array
Project description:A functional gene microarray was developed and used to investigate phytoplankton community composition and gene expression in the English Channel. Genes encoding the CO2 fixation enzyme RuBisCO (rbcL) and the nitrate assimilation enzyme nitrate reductase (NR) representing several major groups of phytoplankton were included as oligonucleotide probes on the 'phytoarray'. Five major groups of eukaryotic phytoplankton that possess the Type 1D rbcL gene were detected, both in terms of presence (DNA) and activity (rbcL gene expression). Changes in relative signal intensity among the Type 1D rbcL probes indicated a shift from diatom dominance in the spring bloom to dominance by haptophytes and flagellates later in the summer. Because of the limitations of a smaller database, NR probes detected fewer groups, but due to the greater diversity among known NR sequences, NR probes provided higher phylogenetic resolution than did rbcL probes, and identified two uncultivated diatom phylotypes as the most abundant (DNA) and active (NR gene expression) in field samples. Unidentified chlorophytes and the diatom Phaeodactylum tricornutum were detected at both the DNA and cDNA (gene expression) levels. The reproducibility of the array was evaluated in several ways and future directions for further improvement of probe development and sensitivity are outlined. The phytoarray provides a relatively high resolution, high throughput approach to assessing phytoplankton community composition in marine environments. Keywords: seawater natural assemblages, functional gene expression
Project description:Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River. Three groups of samples, A, B and C. Every group has 3 replicates.
Project description:Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River.
Project description:Atrazine is one of the most commonly used herbicide and has been frequently detected in estuarine and offshore waters worldwide. As a photosystem Ⅱ inhibitor, atrazine may inhibit phytoplankton from fixating of CO2 and alter its carbon metabolism, which will undoubtedly have negative effect on the primary productivity and carbon sequestration capacity of coastal waters. However, the existing reports mainly focused on agriculture and freshwater ecosystems and are mostly toxicity test with high-dose of atrazine, which have little concern about the negative effects of atrazine on the carbon metabolism of phytoplankton and can’t reflect the actual toxic situation in offshore water. Diatoms are widely distributed in freshwater and oceans and contribute at least 20% of the global CO2 assimilation, which is an ideal model group to assess the ecological risk of atrazine. Here we present a comprehensive analysis of the physiological and genome-wide gene expression characteristics of the diatom P. tricornutum Pt-1 (CCMP 2561) treated with environmental dose of atrazine at different stress stages.
Project description:The principles governing acquisition and interspecies exchange of nutrients in microbial communities and how those exchanges impact community productivity are poorly understood. Here, we examine energy and macronutrient acquisition in unicyanobacterial consortia for which species-resolved genome information exists for all members, allowing us to use multi-omic approaches to predict species’ abilities to acquire resources and examine expression of resource-acquisition genes during succession. Metabolic reconstruction indicated that a majority of heterotrophic community members lacked the genes required to directly acquire the inorganic nutrients provided in culture medium, suggesting high metabolic interdependency. The sole primary producer in consortium UCC-O, cyanobacterium Phormidium sp. OSCR, displayed declining expression of energy harvest, carbon fixation, and nitrate and sulfate reduction proteins but sharply increasing phosphate transporter expression over 28 days. Most heterotrophic members likewise exhibited signs of phosphorus starvation during succession. Though similar in their responses to phosphorus limitation, heterotrophs displayed species-specific expression of nitrogen acquisition genes. These results suggest niche partitioning around nitrogen sources may structure the community when organisms directly compete for limited phosphate. Such niche complementarity around nitrogen sources may increase community diversity and productivity in phosphate-limited phototrophic communities.
Project description:Interventions: Experimental group:Use virtual reality equipment;Control group:Routine medical care measures
Primary outcome(s): Intestinal microflora diversity and community structure distribution;Diamine oxidase;Intestinal fatty acid binding protein;Time of first postoperative defecation;Time of first postoperative exhaust;Recovery time of first bowel sounds
Study Design: Parallel