500 research outputs found

    Studies of a Halophilic NADH Dehydrogenase. 1: Purification and Properties of the Enzyme

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    An NADH dehydrogenase obtained from an extremely halophilic bacterium was purified 570-fold by a combination of gel filtration, chromatography on hydroxyapatite, and ion-exchange chromatography on QAE-Sephadex. The purified enzyme appeared to be FAD-linked and bad an apparent molecular weight of 64000. Even though enzyme activity was stimulated by NaCl, considerable activity (430 % of the maximum activity observed in the presence of 2.5 M NaCl) was observed in the absence of added NaCl. The enzyme was unstable when incubated in solutions of low ionic strength. The presence of NADH enhanced the stability of the enzyme

    Technology Resources for Earthquake Monitoring and Response (TREMOR)

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    Earthquakes represent a major hazard for populations around the world, causing frequent loss of life, human suffering, and enormous damage to homes, other buildings, and infrastructure. The Technology Resources for Earthquake Monitoring and Response (TREMOR) proposal is designed to address this problem. This proposal recommends two prototype systems integrating space-based and ground technology. The suggested pilot implementation is over a 10-year period in three focus countries – China, Japan, and Peru – that are among the areas in the world most afflicted by earthquakes. The first proposed system is an Earthquake Early Warning Prototype System that addresses the potential of earthquake precursors, the science of which is incomplete and considered controversial within the scientific community. We recommend the development and launch of two small satellites to study ionospheric and electromagnetic precursors. In combination with ground-based precursor research, the data gathered will improve existing knowledge of earthquake-related phenomena. The second proposed system is an Earthquake Simulation and Response Prototype. An earthquake simulator will combine any available precursor data with detailed knowledge of the affected areas using a Geographic Information System (GIS) to identify those areas that are most likely to experience the greatest level of damage. Mobile satellite communication hubs will provide telephone and data links between response teams, while satellite navigation systems will locate and track emergency vehicles. We recommend a virtual response satellite constellation composed of existing and future high resolution satellites. We also recommend education and training for response teams on the use of these technologies. The two prototypes will be developed and implemented by a proposed non-profit nongovernmental organization (NGO) called the TREMOR Foundation, which will obtain funding from government disaster management agencies and NGOs. A for-profit subsidiary will market any spin-off technologies and provide an additional source of funding. Assuming positive results from the prototype systems, Team TREMOR recommends their eventual and permanent implementation in all countries affected by earthquakes.Postprint (published version

    Hepatic P450 Enzyme Activity, Tissue Morphology and Histology of Mink (Mustela vison) Exposed to Polychlorinated Dibenzofurans

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    Dose- and time-dependent effects of environmentally relevant concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ) of 2,3,7,8-tetrachlorodibenzofuran (TCDF), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or a mixture of these two congeners on hepatic P450 enzyme activity and tissue morphology, including jaw histology, of adult ranch mink were determined under controlled conditions. Adult female ranch mink were fed either TCDF (0.98, 3.8, or 20 ng TEQTCDF/kg bw/day) or PeCDF (0.62, 2.2, or 9.5 ng TEQPeCDF/kg bw/day), or a mixture of TCDF and PeCDF (4.1 ng TEQTCDF/kg bw/day and 2.8 ng TEQPeCDF/kg bw/day, respectively) for 180 days. Doses used in this study were approximately eight times greater than those reported in a parallel field study. Activities of the cytochrome P450 1A enzymes, ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-deethylase (MROD) were significantly greater in livers of mink exposed to TCDF, PeCDF, and a mixture of the two congeners; however, there were no significant histological or morphological effects observed. It was determined that EROD and MROD activity can be used as sensitive biomarkers of exposure to PeCDF and TCDF in adult female mink; however, under the conditions of this study, the response of EROD/MROD induction occurred at doses that were less than those required to cause histological or morphological changes
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