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.
Project description:The application of chemical dispersants during marine oil spills can affect the community composition and activity of native marine microorganisms. Several studies have indicated that certain marine hydrocarbon-degrading bacteria, such as Marinobacter spp., can be inhibited by chemical dispersants, resulting in lower abundances and/or reduced hydrocarbon-biodegradation rates. In this respect, a major knowledge gap exists in understanding the mechanisms underlying these observed physiological effects. Here, we performed comparative proteomics of the Deepwater Horizon isolate Marinobacter sp. TT1 grown under different conditions that varied regarding the supplied carbon sources (pyruvate vs. n-hexadecane) and whether or not dispersant (Corexit EC9500A) was added, or that contained crude oil in the form of a water-accommodated fraction (WAF) or chemically-enhanced WAF (CEWAF). We characterized the proteins associated with alkane metabolism and alginate biosynthesis in strain TT1, report on its potential for aromatic hydrocarbon biodegradation and present a proposed metabolism of Corexit components as carbon substrates for the strain. Our findings implicate Corexit in affecting hydrocarbon metabolism, chemotactic motility, biofilm formation, and inducing solvent tolerance mechanisms like efflux pumps in strain TT1. This study provides novel insights into dispersant impacts on microbial hydrocarbon degraders that should be taken into consideration for future oil spill response actions.
Project description:Protein expression in Staphylococcus sp. NIOSBK35 isolated from marine environment (mangrove sediments) to different concentrations of arsenic (III)
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.
Project description:Crude oil is the one of the most important natural assets of humankind, yet it is a major environmental pollutant, in particular, in marine environments. One of the largest crude oil polluted areas in the word is the semi-enclosed Mediterranean Sea, where the metabolic potential of indigenous populations towards the chronic pollution at a large scale is yet to be defined, particularly in anaerobic and micro-anaerobic marine sites. Here, we provided a novel insight into the active microbial metabolism in sediments from three environments along the coastline of Italy. Microbial proteomes exhibited prevalence in anaerobic metabolism, not related to the biodegradation directly, suggesting the strong limitation by oxygen induced by the carbon overload. They also point at previously unrecognized metabolic coupling between methane and methanol utilizers as well as sulfur reducers in marine petroleum polluted sediments.
Project description:Coastal marine sediments, as locations of substantial fixed nitrogen loss, are very important to the nitrogen budget and to the primary productivity of the oceans. Coastal sediment systems are also highly dynamic and subject to periodic natural and anthropogenic organic substrate additions. The response to organic matter by the microbial community involved in nitrogen loss processes was evaluated using mesocosms of Chesapeake Bay sediments. Over the course of a 50-day incubation, rates of anammox and denitrification were measured weekly using 15N tracer incubations, and samples were collected for genetic analysis. Rates of both nitrogen loss processes and gene abundances associated with them corresponded loosely, probably because heterogeneities in sediments obscured a clear relationship. The rates of denitrification were stimulated more by the higher organic matter addition, and the fraction of nitrogen loss attributed to anammox slightly reduced. Furthermore, the large organic matter pulse drove a significant and rapid shift in the denitrifier community as determined using a nirS microarray, indicating the diversity of these organisms plays an essential role in responding to anthropogenic inputs. We also suggest that the proportion of nitrogen loss due to anammox in these coastal estuarine sediments may be underestimated due to temporal dynamics as well as from methodological artifacts related to conventional sediment slurry incubation approaches.