Project description:The response of global carbon and nitrogen cycles to future climate change is uncertain. In order to understand the impacts that future changes to climate will have on these cycles, a more detailed understanding of them is essential. This dissertation utilizes a combined approach of molecular biomarkers and proteomic investigations to elucidate historic source material contributions and microbial protein production to contribute to a more thorough understanding of the marine carbon and nitrogen cycles. The examination of molecular organic biomarkers throughout an Arctic sediment core showed the dominant input in the area was from marine sources with lower but steady contributions from terrestrial sources during the Holocene. Attempts to recover proteins from deeper sediments to correlate with lipid biomarkers were unsuccessful but led to the optimization of an extraction protocol for an added protein standard, bovine serum albumin, from sediments. An investigation into the expressed proteome of the heterotrophic marine bacterium, Ruegeria pomeroyi, under environmentally realistic carbon supply conditions during exponential and stationary growth phases identified over 2000 proteins. The most abundant proteins identified were responsible for porins, transport, binding, translation, and protein refolding and could represent potential biomarkers of bacterial processes and/or activity. A parallel study of R. pomeroyi, in which 13C-labeled leucine was added to the culture during exponential growth phase, showed labeled incorporation ranging from 16 to 21% of the total proteins produced depending on growth phase. The widespread distribution of the label among the growth phases indicates active recycling by the bacteria. This study demonstrates a method through which bacterial protein synthesis can be tracked. A study of the marine diatom Thalassiosira pseudonana acclimated to iron replete or iron-limited conditions showed iron-limited organisms increased proteins involved in pathways associated with intracellular protein recycling, the pentose phosphate pathway, lower photosynthetic energy production, enhancement of photorespiration, and increased polysaccharide production. This application of proteomics to the examination of proteins in marine sediments, a marine diatom, and a heterotrophic marine bacterium shows the potential for these techniques to help elucidate the fate of proteins in marine environments and could be used in conjunction with well-established molecular organic marker studies.
Project description:Interventions: ntestinal polyp gruop and colorectal cancer gruop:Nil
Primary outcome(s): bacteria;fungi;archaea;virus
Study Design: Factorial
Project description:Chemical analysis of the compounds present in sediment, although informative, often is not indicative of the downstream biological effects that these contaminants exert on resident aquatic organisms. More direct molecular methods are needed to determine if marine life is affected by exposure to sediments. In this study, we used an aquatic multispecies microarray and q-PCR to investigate the effects on gene expression in juvenile sea bream (Sparus aurata) of two contaminated sediments defined as sediment 1 and 2 respectively, from marine areas in Northern Italy.
Project description:Escaped domesticated individuals can introduce disadvantageous traits into wild populations due to both adaptive differences between population ancestors and human-induced changes during domestication. In contrast to their domesticated counterparts, some endangered wild Atlantic salmon populations encounter during their marine stage large amounts of suspended sediments, which may act as a selective agent. We used microarrays to elucidate quantitative transcriptional differences between a domesticated salmon strain, a wild population and their first-generation hybrids during their marine life stage, to describe transcriptional responses to natural suspended sediments, and to test for adaptive genetic variation in plasticity relating to a history of natural exposure or nonexposure to suspended sediments. We identified 67 genes differing in transcription level among salmon groups. Among these genes, processes related to energy metabolism and ion homoeostasis were over-represented, while genes contributing to immunity and actin-/myosin-related processes were also involved in strain differentiation. Domestic–wild hybrids exhibited intermediate transcription patterns relative to their parents for two-thirds of all genes that differed between their parents; however, genes deviating from additivity tended to have similar levels to those expressed by the wild parent. Sediments induced increases in transcription levels of eight genes, some of which are known to contribute to external or intracellular damage mitigation. Although genetic variation in plasticity did not differ significantly between groups after correcting for multiple comparisons, two genes (metallothionein and glutathione reductase) tended to be more plastic in response to suspended sediments in wild and hybrid salmon, and merit further examination as candidate genes under natural selection.
2012-04-23 | GSE30555 | GEO
Project description:Spirulina necromass degradartion in arctic marine sediments
Project description:Escaped domesticated individuals can introduce disadvantageous traits into wild populations due to both adaptive differences between population ancestors and human-induced changes during domestication. In contrast to their domesticated counterparts, some endangered wild Atlantic salmon populations encounter during their marine stage large amounts of suspended sediments, which may act as a selective agent. We used microarrays to elucidate quantitative transcriptional differences between a domesticated salmon strain, a wild population and their first-generation hybrids during their marine life stage, to describe transcriptional responses to natural suspended sediments, and to test for adaptive genetic variation in plasticity relating to a history of natural exposure or nonexposure to suspended sediments. We identified 67 genes differing in transcription level among salmon groups. Among these genes, processes related to energy metabolism and ion homoeostasis were over-represented, while genes contributing to immunity and actin-/myosin-related processes were also involved in strain differentiation. DomesticM-bM-^@M-^Swild hybrids exhibited intermediate transcription patterns relative to their parents for two-thirds of all genes that differed between their parents; however, genes deviating from additivity tended to have similar levels to those expressed by the wild parent. Sediments induced increases in transcription levels of eight genes, some of which are known to contribute to external or intracellular damage mitigation. Although genetic variation in plasticity did not differ significantly between groups after correcting for multiple comparisons, two genes (metallothionein and glutathione reductase) tended to be more plastic in response to suspended sediments in wild and hybrid salmon, and merit further examination as candidate genes under natural selection. Salmon of three genotypes (strains: 1. wild (Stewiacke River salmon), 2. domesticated (Saint John River salmon), and 3. first generation hybrids between the two strains, were exposed to two environments (treatment: 1. suspended sediments, 2. control: clear water), using eight biological replicates (individuals) of each of the six experimental groups, summing up to 48 individuals, each individual has two technical replicates , each technical replicate has been labelled with a different dye, each technical replicate appears on a different array, dye swaps are equilibrated for arrays that combine individuals from different genotypes and for arrays that combine individuals from the same genotype but different environments. Technical replicates of individuals always appear once on arrays that compare between environments and once on arrays that compare among genotypes. In total there are 48 arrays.