Genes for selenium dependent and independent formate dehydrogenase in the gut microbial communities of three lower, wood-feeding termites and a wood-feeding roach

The bacterial Wood-Ljungdahl pathway for CO_2-reductive acetogenesis is important for the nutritional mutualism occurring between wood-feeding insects and their hindgut microbiota. A key step in this pathway is the reduction of CO_2 to formate, catalysed by the enzyme formate dehydrogenase (FDH). Putative selenocysteine- (Sec) and cysteine- (Cys) containing paralogues of hydrogenase-linked FDH (FDH_H) have been identified in the termite gut acetogenic spirochete, Treponema primitia, but knowledge of their relevance in the termite gut environment remains limited. In this study, we designed degenerate PCR primers for FDH_H genes (fdhF) and assessed fdhF diversity in insect gut bacterial isolates and the gut microbial communities of termites and cockroaches. The insects examined herein represent three wood-feeding termite families, Termopsidae, Kalotermitidae and Rhinotermitidae (phylogenetically 'lower' termite taxa); the wood-feeding roach family Cryptocercidae (the sister taxon to termites); and the omnivorous roach family Blattidae. Sec and Cys FDH_H variants were identified in every wood-feeding insect but not the omnivorous roach. Of 68 novel alleles obtained from inventories, 66 affiliated phylogenetically with enzymes from T. primitia. These formed two subclades (37 and 29 phylotypes) almost completely comprised of Sec-containing and Cys-containing enzymes respectively. A gut cDNA inventory showed transcription of both variants in the termite Zootermopsis nevadensis (family Termopsidae). The gene patterns suggest that FDH_H enzymes are important for the CO_2-reductive metabolism of uncultured acetogenic treponemes and imply that the availability of selenium, a trace element, shaped microbial gene content in the last common ancestor of dictyopteran, wood-feeding insects, and continues to shape it to this day

Applications of HCMM data to soil moisture snow and estuarine current studies

There are no author-identified significant results in this report

Junction Electron-Beam-Induced Current Techniques for the Analysis of Photovoltaic Devices

A number of useful electron-beam-induced current (EBIC) techniques have evolved through the study of junction behavior in photovoltaic (PV) devices in cross section as a function of light and voltage bias, temperature, and electron beam scanning parameters. The necessary hardware modifications, the techniques themselves, and their applications are presented. In the case of PV devices, light and/or voltage biasing the entire device while electron probing it in cross section permits the observation of the distribution of the narrowing or extension of the space-charge region. Monitoring the junction behavior as a function of temperature has at least two applications. In situ heating of the device in the junction EBIC (JEBIC) mode permits the observation of the rate of movement of the junction further into the material as a function of time and temperature. Through low-temperature studies of cross sections, the change in the material\u27s electrical properties have been recorded and correlated with device I-V and quantum efficiency measurements at these temperatures. Further, the JEBIC profile has been used to predict the quantum efficiency of the device. In the case of thin-film CdS/CuinSe2 devices, newly developed JEBIC techniques have been instrumental in determining the role of oxygen in improving device performance and stability

Application of HCMM data to soil moisture snow and estuarine current studies

There are no author-identified significant results in this report

Applications of HCMM data to soil moisture snow and estuarine current studies

There are no author-identified significant results in this report

Selected Hydrologic Applications of LANDSAT-2 Data: an Evaluation

The author has identified the following significant results. Estimates of soil moisture were obtained from visible, near-IR gamma ray and microwave data. Attempts using GOES thermal-IR were unsuccessful due to resolutions (8 km). Microwaves were the most effective at soil moisture estimates, with and without vegetative cover. Gamma rays provided only one value for the test site, produced by many data points obtained from overlapping 150 meter diameter circles. Even though the resulting averaged value was near the averaged field moisture value, this method suffers from atmospheric contaminants, the need to fly at low altitudes, and the necessity of prior calibration of a given site. Visible and near-IR relationships are present for bare fields but appear to be limited to soil moisture levels between 5 and 20%. The densely vegetated alfalfa fields correlated with near-IR reflectance only; soil moisture values from wheat fields showed no relation to either or near-IR MSS data