Project description:Microbial decomposition of soil organic carbon (SOC) in Arctic permafrost is one of the most important, but poorly understood, factors in determining the greenhouse gas feedback of tundra ecosystems to climate. Here, we examine changes in the structure of microbial communities in an anoxic incubation experiment at either –2 or 8 °C for up to 122 days using both an organic and a mineral soil collected from the Barrow Environmental Observatory in northern Alaska, USA. Soils were characterized for SOC and geochemistry, and GeoChips 5.0 were used to determine microbial community structure and functional genes associated with C availability and Fe(III) reduction.
Project description:These metaproteomic datasets are from active layer soil samples collected from the area of Toolik Field Station, Arctic Alaska, USA. These datasets are described and analyzed in the forthcoming paper, "Functional partitioning and vegetational variation among Arctic soil bacteria revealed by metaproteomics."
Project description:Permafrost soil in high latitude tundra is one of the largest terrestrial carbon (C) stocks and is highly sensitive to climate warming. Understanding microbial responses to warming induced environmental changes is critical to evaluating their influence on soil biogeochemical cycles. In this study, a functional gene array (i.e. GeoChip 4.2) was used to analyze the functional capacities of soil microbial communities collected from a naturally degrading permafrost region in Central Alaska. Varied thaw history was reported to be the main driver of soil and plant differences across a gradient of minimally, moderately and extensively thawed sites. Compared with the minimally thawed site, the number of detected functional gene probes across the 15-65 cm depth profile at the moderately and extensively thawed sites decreased by 25 % and 5 %, while the community functional gene beta-diversity increased by 34% and 45%, respectively, revealing decreased functional gene richness but increased community heterogeneity along the thaw progression. Particularly, the moderately thawed site contained microbial communities with the highest abundances of many genes involved in prokaryotic C degradation, ammonification, and nitrification processes, but lower abundances of fungal C decomposition and anaerobic-related genes. Significant correlations were observed between functional gene abundance and vascular plant primary productivity, suggesting that plant growth and species composition could be co-evolving traits together with microbial community composition. Altogether, this study reveals the complex responses of microbial functional potentials to thaw related soil and plant changes, and provides information on potential microbially mediated biogeochemical cycles in tundra ecosystems.
Project description:The effects of two years' winter warming on the overall fungal functional gene structure in Alaskan tundra soil were studies by the GeoChip 4.2 Resuts showed that two years' winter warming changed the overall fungal functional gene structure in Alaskan tundra soil.
Project description:Clipping (i.e., harvesting aboveground plant biomass) is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties, plant and microbial communities, in particular microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38-137% in response to either clipping or the combined treatment, which could weaken the long-term soil carbon stability and trigger a positive feedback to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization and denitrification by 32-39%. The potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium caused by clipping alone, and contribute to unchanged plant biomass. Moreover, clipping tended to interact antagonistically with warming, especially on nitrogen cycling genes, demonstrating that single factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties, as well as the abundance and structure of soil microbial functional genes. The aboveground biomass removal for biofuel production needs to be re-considered as the long-term soil carbon stability may be weakened.
Project description:Whole blood was collected as part of annual health assessments of beluga whales from the healthy Bristol Bay, Alaska stock during 2012-2014. Gene expression from 24 animals (8 from each year) was analyzed to establish baseline information on the content and variation of the beluga whale blood transcriptome.
Project description:Only 59% of Alaska Native people have been adequately screened for colorectal cancer (CRC) despite having the highest reported incidence of CRC in the world. A new at-home multi-target stool DNA screening test (MT-sDNA; Cologuard) with high sensitivity for pre-cancerous polyps and CRC is now available. MT-sDNA has not been tested for feasibility or acceptability within the Alaska tribal health care delivery system, and it is unknown whether use of this new test will increase Alaska Native CRC screening rates. The long-term study goal is to improve screening and reduce CRC-attributable mortality. The objective of this application is to test the effectiveness of MT-sDNA for increasing CRC screening in Alaska Native communities using a mixed methods, community-based participatory research (CBPR) approach. The study will be conducted in collaboration with regional Tribal health organizations responsible for providing health care to geographically remote Alaska Native communities. Although the proposed implementation strategy is evidence-informed and promising, it is novel in that MT-sDNA has not been evaluated in the tribal health setting or among rural/remote populations. Using the Social Ecological Model, the research will be multi-level, examining influence on patients, providers, and tribal health organizations (THOs). This research study will pursue two specific aims: (1) Identify patient-, provider-, and system-level factors associated with CRC screening preferences, uptake, and follow-up; and (2) test the effectiveness of graded intensity MT-sDNA intervention in the Alaska Native community setting. For the first aim, focus groups with Alaska Native people who are not adherent to CRC screening guidelines and interviews with healthcare providers will be used to identify factors for future intervention. For the second aim, a three-arm cluster randomized controlled trial (high intensity with patient navigation, medium intensity with mailed reminders, usual care) will provide evidence on the MT-sDNA usefulness (MT-sDNA sample quality and neoplastic yield) as well as the first data on MT-sDNA follow up adherence rates in the Alaska Native population, which will inform plans to scale-up the intervention model. This research has the potential to sustainably improve public health by increasing CRC screening rates among a rural/remote tribal population as well as provide a model for other integrated health systems that provide care to high-risk or underserved populations in the U.S. and worldwide.
Project description:Because of severe abiotic limitations, Antarctic soils represent simplified ecosystems, where microorganisms are the principle drivers of nutrient cycling. This relative simplicity makes these ecosystems particularly vulnerable to perturbations, like global warming, and the Antarctic Peninsula is among the most rapidly warming regions on the planet. However, the consequences of the ongoing warming of Antarctica on microorganisms and the processes they mediate are unknown. Here, using 16S rRNA gene pyrosequencing and qPCR, we report a number of highly consistent changes in microbial community structure and abundance across very disparate sub-Antarctic and Antarctic environments following three years of experimental field warming (+ 0.5-2°C). Specifically, we found significant increases in the abundance of fungi and bacteria and in the Alphaproteobacteria-to-Acidobacteria ratio. These alterations were linked to a significant increase in soil respiration. Furthermore, the shifts toward generalist or opportunistic bacterial communities following warming weakened the linkage between bacterial diversity and functional diversity. Warming also increased the abundance of some organisms related to the N-cycle, detected as an increase in the relative abundance of nitrogenase genes via GeoChip microarray analyses. Our results demonstrate that soil microorganisms across a range of sub-Antarctic and Antarctic environments can respond consistently and rapidly to increasing temperatures, thereby potentially disrupting soil functioning.