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.
Project description:Increasing utilization and human population density in the coastal zone is widely believed to place increasing stresses on the resident biota, but confirmation of this belief is somewhat lacking. While we have solid evidence that highly disturbed estuarine systems have dramatic changes in the resident biota (black and white if you will), we lack tools that distinguish the shades of grey. In part this lack of ability to distinguish shades of grey stems from the analytical tools that have been applied to studies of estuarine systems and perhaps more important is the insensitivity of the biological end points that we have used to assess these impacts. In this paper we will present data on the phenotypic adjustments as measured by transcriptomic signatures of a resilient organism (oysters) to land use practices in the surrounding watershed using advanced machine learning algorithms. We will demonstrate that such an approach can reveal subtle and meaningful shifts in oyster gene expression in response to land use. Further, the data shows that gill tissues are far more responsive and provide superior discrimination of land use classes than hepatopancreas and that transcript encoding proteins involved in energy productions, protein synthesis and basic metabolism are more robust indicators of land use than classic biomarkers such as metallothioneins, GST and cytochrome P450. Keywords: Comparative genomics, ecogenomics. Tissue differences, impacts of land use and contaminants on gene expression.
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. Two color array (Cy3 and Cy5): the universal standard 20-mer oligo is printed to the slide with a 70-mer oligo (an archetype). Environmental DNA sequences (fluoresced with Cy3) within 15% of the 70-mer conjugated to a 20-mer oligo (fluoresced with Cy5) complementary to the universal standard will bind to the oligo probes on the array. Signal is the ratio of Cy3 to Cy5. Three replicate probes were printed for each archetype. Two replicate arrays were run on duplicate targets.
Project description:Increasing utilization and human population density in the coastal zone is widely believed to place increasing stresses on the resident biota, but confirmation of this belief is somewhat lacking. While we have solid evidence that highly disturbed estuarine systems have dramatic changes in the resident biota (black and white if you will), we lack tools that distinguish the shades of grey. In part this lack of ability to distinguish shades of grey stems from the analytical tools that have been applied to studies of estuarine systems and perhaps more important is the insensitivity of the biological end points that we have used to assess these impacts. In this paper we will present data on the phenotypic adjustments as measured by transcriptomic signatures of a resilient organism (oysters) to land use practices in the surrounding watershed using advanced machine learning algorithms. We will demonstrate that such an approach can reveal subtle and meaningful shifts in oyster gene expression in response to land use. Further, the data shows that gill tissues are far more responsive and provide superior discrimination of land use classes than hepatopancreas and that transcript encoding proteins involved in energy productions, protein synthesis and basic metabolism are more robust indicators of land use than classic biomarkers such as metallothioneins, GST and cytochrome P450. Keywords: Comparative genomics, ecogenomics. Tissue differences, impacts of land use and contaminants on gene expression. Oysters were collected from 11 tidal creeks in Georgia, South Carolina and North Carolina at sites variously impacted by human development. A total of 267 individuals were examined for gene expression profiles in gill and hepatopancreas tissues for a total of 534 arrays. The data were filtered though standard tools and ultimately analyzed using advance machine learning techniques.
Project description:Land cover change has long been recognized that marked effect the amount of soil organic carbon. However, little is known about microbial-mediated effect processes and mechanism on soil organic carbon. In this study, the soil samples in a degenerated succession from alpine meadow to alpine steppe meadow in Qinghai-Tibetan Plateau degenerated, were analyzed by using GeoChip functional gene arrays.
2017-01-05 | GSE93158 | GEO
Project description:Land use, soil microorganisms, organic carbon and biodiversity: putting the pieces together
Project description:The use of a systems biology approach to analyze common and specific mechanisms of liver toxicity induced by munitions compounds TNT, 2,6-DNT, 2,4-DNT, 4A-DNT, and 2A-DNT The munitions compound 2,4,6-trinitrotoluene (TNT), its environmental degradation products 2-amino-4,6-dinitrotoluene (2A-DNT) and 4-amino-2,6-dinitrotoulene (4A-DNT), and two other munitions, 2,4-dinitrotoluene (2,4-DNT) and 2,4-dinitrotoluene (2,6-DNT) contaminate contaminate land, water and retired ammunitions plants. The release of these compounds to the environment is due to military activities and a series of manufacturing processes. Although toxicity has been characterized for these compounds, little is known of their mechanism of action. Here we describe to use an integrative systems biology approach including toxicology, pathology, transcriptomics, metabolomics, gene function classification, pathway analysis and gene network modeling to try to understand the mechanisms of toxicity of these compounds.
Project description:Soil microorganisms act as gatekeepers for soil-atmosphere carbon exchange by balancing the accumulation and release of soil organic matter. However, poor understanding of the mechanisms responsible hinders the development of effective land management strategies to enhance soil carbon storage. Here we empirically test the link between microbial ecophysiological traits and topsoil carbon content across geographically distributed soils and land use contrasts. We discovered distinct pH-controls on microbial mechanisms of carbon accumulation. Land use intensification in low-pH soils that increased pH above a threshold (~ 6.2) lead to carbon loss through increased decomposition following alleviation of acid-retardation of microbial growth. However, loss of carbon with intensification in near neutral-pH soils was linked to decreased microbial biomass and reduced growth efficiency that was, in turn, related to tradeoffs with stress alleviation and resource acquisition. Thus, less intensive management practices in near neutral-pH soils have more potential for carbon storage through increased microbial growth efficiency; whereas, in acidic soils microbial growth is a bigger constraint on decomposition rates.