Attaining High Quality Soft White Winter Wheat through Optimal Management of Nitrogen, Residue and Soil Microbes | 0435472 | REARDON C L | 09/06/2018 | 09/05/2023 | COMPLETE | PENDLETON | Not applicable | Obj. 1: Extend the N replacement approach to soft white winter wheat for guiding precision management of fertilizer N and crop residue to optimize soil microbial processes and maximize the biological potential of soil. 1A: Evaluate grain protein concentration and yield response to N under varying levels of water to define the critical protein level and fertilizer N equivalent to a unit change in protein for popular cultivars of soft white winter wheat. 1B: Determine whether uniformity of protein levels in the crop can be achieved with the precision N replacement approach. 1C: Adapt instruments and algorithms to support on-farm implementation of the N replacement approach to precision fertilizer management in dryland wheat production systems. 1D: Evaluate the effects of residue management (standing, distributed on the soil surface, or removed) on the plant-available N, precipitation capture efficiency, crop productivity, weed density, and microbial activity during the 13 months of fallow. Obj. 2: Identify whether soil microbial communities adapted to dry environments benefit plant fitness under water limited conditions. 2A: Identify the composition of microbial consortia naturally adapted to low water availability. 2B: Determine whether cultivar selection and N management can be manipulated to shift the structure and function of microbial communities to benefit plants under water stress. Obj. 3. Develop resilient cropping systems and strategies that increase resilience, improve economic returns, and enhance ecosystem services; assess their economic and environmental performance of various cropping systems in concert with their supporting components; and develop decision support systems for optimizing agronomic production in these cropping systems. 3A: Compare economic returns from the variable N replacement approach based on previous seasonâ¿¿s site-specific SWW crop yield data and conventional uniform N placement based on field bulk soil sampling and laboratory testing. 3B: Increase dryland farming resilience by developing cropping systems more intensive and diverse than the conventional winter wheat-fallow system. 3C: Investigate the yields and economic returns of alternative crops following winter wheat and winter wheat following cover crops across low and intermediate precipitation zones using current and future climate scenarios. Obj. 4. Increase the sustainability resilience and tolerance of the dryland crop production system to biotic and abiotic stressors through improved understanding of developmental, environmental, and management factors that limit plant health and growth, including but not limited to stress tolerance, water use efficiency, and disease resistance. 4A: Evaluate stress indicators and yield components of wheat in alternative cropping systems compared to wheat-fallow with relation to soil water availability, disease incidence, and rotational crop morphology. 4B: Investigate crop response to water deficit, high temperature, and/or nitrogen availability. |
Bacterial Methylation of Mine-Derived Inorganic Mercury in Lake and Estuarine Sediments | 0201896 | Nelson, D | 10/01/2009 | 09/30/2014 | COMPLETE | DAVIS | California's legacy of inorganic mercury pollution from abandoned mines is of concern due to its potential conversion to methylmercury. Bacteria living in oxygen-depleted sediments produce this especially toxic form of mercury, which is readily biomagnified in predatory fish and birds near the apex of aquatic food webs. We have recently shown that a group called "iron-reducing bacteria" are as active at producing methylmercury as other bacteria, called "sulfate-reducers", which were previously believed to perform the bulk of these transformations in marine and freshwater sediments. The current proposal will continue to refine experiments based on natural sediments to determine the general importance of iron-reducers as mercury methylators throughout the sediments of a lake and an estuary impacted by typical mine-derived mercury. Pure cultures of abundant iron-reducing bacteria will also be isolated from mine-impacted marine sediments and assayed for their ability to produce methylmercury from the divalent inorganic form. A variety of stakeholder groups have been interested in our basic research findings on these and related topics to date. The PI will continue to keep these groups informed of our new findings and any possible implications for remediation actions. | The research objectives for this project are as follows: (1) For mine-impacted sediments of Clear Lake, determine the relative contribution of sulfate-reducing bacteria to methylation of mercury while altering native sediment properties and inorganic mercury levels as little as possible. (2) For mine-impacted sediments of Clear Lake that are first manipulated to biologically deplete sulfate and oxidized iron, determine the relative rates of mercury methylation upon supplementation with each biological oxidant separately and both together. (3) For mine-impacted sediments of Walker Creek Estuary and a control site, determine the proportional contribution of sulfate-reducing bacteria to methylation of mercury while altering native sediment properties and inorganic mercury levels as little as possible. (4) For a spectrum of sediment types from Walker Creek Estuary, isolate pure cultures of marine iron-oxidizing bacteria and test the per-cell rates of production of methylmercury for representative cultures. (5) Use bioaccumulation of methylmercury in the muscle tissue of the lined shore crab, PACHYGRAPSUS CRASSIPES, to determine the extent and magnitude of the impact of mercury from Walker Creek on biota around Tomales Bay; a site showing minimal impact will be selected as control sediment for the third objective. . Under the earlier version of this project the PI presented new basic research findings that have implications for mercury management policy to the following stakeholder groups: Delta Tributaries Mercury Council, San Francisco Estuary Institute, San Francisco Bay Water Board. These presentations, made in person or via dissemination of unpublished research findings, were in response to requests from these groups, and we will continue to disseminate our findings in this manner as they become available. Additionally, our report on our Walker Creek Estuary studies, which has been posted on the UC Office of the President Coastal Environmental Quality Initiative website (http://repositories.cdlib.org/ucmarine/ceqi/040), had 742 full-text downloads in the first 30 months of posting (2006-12-13) and continues to be downloaded at a steady pace. We will continue to present our findings at scientific meetings and in research journal articles. A recent peer-review of an earlier version of our pending manuscript on the Walker Creek Estuary studies characterized our 2006 publication (Fleming et al., 2006, Mercury methylation from unexpected sources: molybdate-inhibited freshwater sediments and an iron-reducing bacterium. Applied and Environmental Microbiology 72:457-464) as follows: "In this reviewer's opinion, that finding was one of the most significant advances in Hg biogeochemistry in recent years, because for over 20 years prior to the 2006 paper, SRB [sulfate-reducing bacteria] were the focus of all research on Hg methylation." Thus, we believe that our current basic research emphasis on establishing the generality of those earlier findings continues to have strong implications for environmental policy and remediation of contaminated sites. |
PROTEASOMES IN THE ARCHAEA | 0177264 | Maupin, J. A. | 11/20/1997 | 03/31/2009 | ACTIVE | GAINESVILLE | The Archaea, such as methanogens and hyperthermophiles, play a major role in the global carbon cycle and production of beneficial products due to their extreme metabolic diversity. However, very little is known about protein turnover in this class of organisms. The purpose of this study is to learn more about the role of energy-dependent proteolysis as a regulatory process in the Archaea. | The objectives of this project are to investigate the structure and function of the proteasome (a) large-molecular-weight proteinase) from the acetotrophic methanogen Methanosarcina thermophila. The results are expected to: (i) advance the field of acetotrophic methanogenesis which accounts for over 60% of the biologically produced methane (a green-house gas), (ii) expand the fundamental knonwledge of the evolution, mechanism, and function of proteasomes in all of nature; (iii) provide a broader underestanding of the biochemistry, genetics, and physiology of M. thermophila and the methanogenic Archaea; and (iv) help to further define the evolutionary relationshps between the Archaea and Eucarya domains. |