Widespread detoxifying NO reductases impart a distinct isotopic fingerprint on NO under anoxia.

Nitrous oxide (NO), a potent greenhouse gas, can be generated by compositionally complex microbial populations in diverse contexts. Accurately tracking the dominant biological sources of NO has the potential to improve our understanding of NO fluxes from soils as well as inform the diagnosis of human infections. Isotopic "Site Preference" (SP) values have been used towards this end, as bacterial and fungal nitric oxide reductases produce NO with different isotopic fingerprints.

The contrasting roles of nitric oxide drive microbial community organization as a function of oxygen presence.

Microbial assemblages are omnipresent in the biosphere, forming communities on the surfaces of roots and rocks and within living tissues. These communities can exhibit strikingly beautiful compositional structures, with certain members reproducibly occupying particular spatiotemporal microniches. Despite this reproducibility, we lack the ability to explain these spatial patterns.

Spatial Ecology of the Human Tongue Dorsum Microbiome.

A fundamental question in microbial ecology is how microbes are spatially organized with respect to each other and their host. A test bed for examining this question is the tongue dorsum, which harbors a complex and important microbial community. Here, we use multiplexed fluorescence spectral imaging to investigate the organization of the tongue microbiome at micron to hundred-micron scales.

Semi-blind sparse affine spectral unmixing of autofluorescence-contaminated micrographs.

Motivation: Spectral unmixing methods attempt to determine the concentrations of different fluorophores present at each pixel location in an image by analyzing a set of measured emission spectra. Unmixing algorithms have shown great promise for applications where samples contain many fluorescent labels; however, existing methods perform poorly when confronted with autofluorescence-contaminated images.

Results: We propose an unmixing algorithm designed to separate fluorophores with overlapping emission spectra from contamination by autofluorescence and background fluorescence.

UV-Stressed Daphnia pulex Increase Fitness through Uptake of Vitamin D3.

Ultraviolet radiation is known to be highly variable in aquatic ecosystems. It has been suggested that UV-exposed organisms may demonstrate enough phenotypic plasticity to maintain the relative fitness of natural populations. Our long-term objective is to determine the potential photoprotective effect of vitamin D3 on Daphnia pulex exposed to acute or chronic UV radiation.