Search Results for: gu y

Retail poultry products are known sources of antibiotic-resistant Escherichia coli, a major human health concern. Consumers have a range of choices for poultry, including conventional, organic, kosher, and raised without antibiotics (RWA) – designations that are perceived to indicate differences in quality and safety. However, whether these categories vary in the frequency of […]

Foliar chemistry influences leaf decomposition, but little is known about how litter chemistry affects the assemblage of bacterial communities during decomposition. Here we examined relationships between initial litter chemistry and the composition of the bacterial community in a stream ecosystem. We incubated replicated genotypes of Populus fremontii and P. angustifolia leaf litter that differ […]

Soil microbial organisms are central to carbon (C) and nitrogen (N) transformations in soils, yet not much is known about the stable isotope composition of these essential regulators of element cycles. We investigated the relationship between C and N availability and stable C and N isotope composition of soil microbial […]

Understanding how elevated atmospheric CO2 alters the formation and decomposition of soil organic carbon (SOC) is important but challenging. If elevated CO2 induces even small changes in rates of formation or decay of SOC, there could be substantial feedbacks on the atmosphere’s concentration of CO2. However, the long turnover times […]

In order to study controls on metabolic processes in soils, we determined the dynamics of 13CO2 production from two position-specific 13C-labeled pyruvate isotopologues in the presence and absence of glucose, succinate, pine, and legume leaf litter, and under anaerobic conditions. We also compared 13CO2 production in soils along a semiarid […]

We used metabolic tracers and modeling to analyze the response of soil metabolism to a sudden change in temperature from 4 to 20 °C. We hypothesized that intact soil microbial communities would exhibit shifts in pentose phosphate pathway and glycolysis activity in the same way as is regularly observed for individual […]

Ecosystems regulate climate through biogeochemistry and biophysics, but current policies only recognize biogeochemical influences. A new proposal to include biophysical effects changes the climate value of ecosystems, and sets the stage to expand the suite of climate regulation services considered in global policies and carbon markets.

Increased atmospheric CO2 and rising temperatures are expected to affect rice yields and greenhouse-gas (GHG) emissions from rice paddies1, 2, 3, 4. This is important, because rice cultivation is one of the largest human-induced sources of the potent GHG methane5 (CH4) and rice is the world’s second-most produced staple crop6. […]

Understanding river food webs requires distinguishing energy derived from primary production in the river itself (autochthonous) from that produced externally (allochthonous), yet there are no universally applicable and reliable techniques for doing so. We compared the natural abundance stable isotope ratios of hydrogen (δD) of allochthonous and autochthonous energy sources […]

Semen is a major vector for HIV transmission, but the semen HIV RNA viral load (VL) only correlates moderately with the blood VL. Viral shedding can be enhanced by genital infections and associated inflammation, but it can also occur in the absence of classical pathogens. Thus, we hypothesized that a […]