6 research outputs found
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Impacts of woody encroachment on the fate of soil CO (sub 2) in grassland watersheds
Woody vegetation is encroaching into grasslands worldwide. Previous research has shown that woody encroachment impacts stream flow, nutrient concentrations, and suspended solid loads. However, little is known about deeper impacts, including impacts to groundwater residence time and composition. We examined these impacts at Konza Prairie Biological Station, a native tallgrass prairie in the Flint Hills of Kansas, USA. Previous research in the study area has found that groundwater CO (sub 2) levels are rising and we hypothesize that woody encroachment may be a driver. To help test this hypothesis, we compared groundwater chemistry and residence time between two watersheds, which differ in levels of woody encroachment (20% and 40%) as a result of differences in watershed burn frequency (1 yr vs 4 yr, respectively). Every three weeks during the 2022 water year, we collected groundwater and stream samples from each watershed and analyzed them for major ion chemistry. Geochemical modeling calculations indicate that an average of 4.4 mmol of CO (sub 2) is added per liter of recharge in the more encroached watershed whereas 4.9 mmol of CO (sub 2) is added per liter of recharge in the less encroached watershed. Groundwater residence time tracers, SF6 and CFCs, collected at four times during the study period do not reveal clear differences between the watersheds. Groundwater residence time varied mostly as a function of the source of groundwater and the time of sample collection and thus do not appear to explain differences in CO (sub 2) inputs between watersheds. Instead, we interpret that differences in CO (sub 2) inputs reflect differences in the residence time of recharge water in the overlying soils. Woody encroachment alters soil root distributions, which in turn can increase soil hydraulic conductivity. If water passes through soils more quickly during recharge, kinetic reaction path modeling indicates that greater weathering occurs deeper in the subsurface rather than in the soil, which decreases the amount of dissolved inorganic carbon the groundwater can store, consistent with our measured groundwater chemistries. These findings suggest that woody encroachment is not driving the increase in groundwater CO (sub 2) inputs over time but is instead causing differences in CO (sub 2) levels between watersheds through its impact on soil hydraulic properties
Functionalized nanoparticles for bioanalysis by SERRS
Metallic nanoparticles can be used as basic materials for a wide variety of purposes including building blocks for nanoassemblies, substrates for enhanced spectroscopies such as fluorescence and Raman and as labels for biomolecules. In the present paper, we report how silver and gold nanoparticles can be functionalized with specific biomolecular probes to interact in a specific manner with a target molecule to provide a change in the properties of the nanoparticles which can be measured to indicate the molecular recognition event. Examples of this approach include DNA hybridization to switch on SERRS (surface-enhanced resonance Raman scattering) when a specific target sequence is present, the use of nanoparticles for in vivo SERRS imaging and the use of nanoparticles functionalized with antibodies to provide a new type of immunoassay. These examples indicate how nanoparticles can be used to provide highly sensitive and informative data from a variety of biological systems when used in combination with SERRS
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Interspecies regulatory landscapes and elements revealed by novel joint systematic integration of human and mouse blood cell epigenomes.
Knowledge of locations and activities of cis-regulatory elements (CREs) is needed to decipher basic mechanisms of gene regulation and to understand the impact of genetic variants on complex traits. Previous studies identified candidate CREs (cCREs) using epigenetic features in one species, making comparisons difficult between species. In contrast, we conducted an interspecies study defining epigenetic states and identifying cCREs in blood cell types to generate regulatory maps that are comparable between species, using integrative modeling of eight epigenetic features jointly in human and mouse in our Validated Systematic Integration (VISION) Project. The resulting catalogs of cCREs are useful resources for further studies of gene regulation in blood cells, indicated by high overlap with known functional elements and strong enrichment for human genetic variants associated with blood cell phenotypes. The contribution of each epigenetic state in cCREs to gene regulation, inferred from a multivariate regression, was used to estimate epigenetic state Regulatory Potential (esRP) scores for each cCRE in each cell type, which were used to categorize dynamic changes in cCREs. Groups of cCREs displaying similar patterns of regulatory activity in human and mouse cell types, obtained by joint clustering on esRP scores, harbored distinctive transcription factor binding motifs that were similar between species. An interspecies comparison of cCREs revealed both conserved and species-specific patterns of epigenetic evolution. Finally, we showed that comparisons of the epigenetic landscape between species can reveal elements with similar roles in regulation, even in the absence of genomic sequence alignment.NI