Sulfate-reducing bacteria: Microbiology and physiology

The sulfate reducing bacteria, the first nonphotosynthetic anaerobic bacteria demonstrated to contain c type cytochromes, perform electron transfer coupled to phosphorylation. A new bioenergetic scheme for the formation of a proton gradient for growth of Desulfovibrio on organic substrates and sulfate involving vectors electron transfer and consistent with the cellular localization of enzymes and electron transfer components was proposed. Hydrogen is produced in the cytoplasm from organic substrates and, as a permease molecule diffuses rapidly across the cytoplasmic membrane, it is oxidized to protons and electrons by the periplasmic hydrogenase. The electrons only are transferred across the cytoplasmic membrane to the cytoplasm where they are used to reduce sulfate to sulfide. The protons are used for transport or to drive a reversible ATPOSE. The net effect is the transfer of protons across the cytoplasmic membrane with the intervention of a proton pump. This type of H2 cycling is relevant to the bioenergetics of other types of anaerobic microorganisms

Beetle fauna of the island of Tobago, Trinidad and Tobago, West Indies

Tobago is a biologically rich but poorly investigated island. In this paper we report the occurrence of 672 species of beetles representing 69 families. Of these, only 95 had been previously reported from the island

Optimal Conditions for Kinetic Study of Succinate Dehydrogenase in Rat Liver

Succinate dehydrogenase (SDH) commonly is assayed as a marker enzyme for mitochondrial activity. The literature presents numerous conditions for conducting this assay due to the fact that, it has been difficult to get sufficient reduction of the acceptor dye, 2,3,5-triphenyl-2H-tetrazolium chloride (TTC). This study was undertaken to optimize the SDH-catalyzed reduction of TTC dye by evaluation of a greater range of molor ratios of TTC to succinate and by further evaluation of additives reported as beneficial. Improvement in enzyme specific activity was achieved by liver perfusion via the left cardiac ventricle with homogenizing solution. Increase in TTC from 1 to 10 mM and further increase to 20 mM resulted in major improvement in color production. The greatest improvement in apparent activity was achieved by addition of 1 mM phenozine methosulfate, a hydrogen transfer mediator. Use of CaCI₂. EDTA, Triton X-100, NaN₃ and KCN was not beneficial. The above modifications of the SDH assay resulted in greater sensitivity, the conduct of a greater number of assays with less tissue and the sacrifice of fewer animals

Optically controlled energy transfer in stacked and coplanar polycyclic chromophores

In the search for enhanced control over the process of resonance energy transfer in multichromophore molecular systems, all-optical mechanisms offer many significant advantages over other systems. One recently conceived scheme, based on the optical switching of energy transfer, is achieved by coupling a normally forbidden decay transition with pulses of off-resonant laser light. Earlier work has suggested that such systems could offer levels of efficiency that might approach those associated with the usual Forster mechanism. In this Letter, the ab initio results of specific calculations on stacked and coplanar polycyclic chromophores are reported. The results show that by judicious choice of electronic state and laser wavelength, much higher levels of efficiency are achievable. A possible scheme for the implementation of such a system is discussed with regard to its potential use in energy harvesting and optical switching applications. © 2010 American Chemical Society

Analysis of Arkansas Fur Harvest Records - 1942-1984: II. Species Accounts

Fur harvest records were maintained by the Arkansas Game and Fish Commission on the following 16 furbearers: badger, beaver, bobcat, eastern spotted skunk (civet), coyote, gray fox, long-tailed weasel, mink, muskrat, nutria, opossum, raccoon, red fox, red wolf, river otter, and striped skunk. These harvest records were analyzed for each species in terms of mean pelt price and numbers of pelt sold by region (Ozark Mountains, Ouachita Mountains, Gulf Coastal Plain, and Mississippi Delta) per year. Historical or biological influences important in interpreting species accounts are presented

The stratigraphy and sedimentology of the Sentinel Butte Formation (Paleocene) in south-central Williams County, North Dakota

Approximately 163 meters (535 feet) of the Paleocene Sentinel Butte Formation crop out in southcentral Williams county, North Dakota. To determine their mode of deposition and stratigraphic position within the formation, twelve stratigraphic sections were measured. These strata were deposited in alternating fluvial and lacustrine environments as determined by sedimentary structures, lithology, lithologic sequences, and fossil occurrences. A fining upward trend in grain size of the tabular sandstones, and the identification of epsilon cross-stratification in the tabular sandstones support a fluvial origin for some of the strata. The strongest evidence for the interpretation of lacustrine deposition is the presence of limestone bodies within these strata. Examination of thin sections taken from some of the limestones revealed a primary mode of origin for the CaC03 • Additional evidence for lacustrine deposition is the presence of thin lignitic layers directly overlying strata lacking root traces. The identification of the upper sand of the Sentinel Butte Formation within the uppermost exposures of this area, and the presence of the Sentinel Butte tuff marker unit in the region just south of the study area suggests that the upper 3/4 of the Sentinel Butte Formation is exposed in this area. Projection of the Bullion Creek-Sentinel Butte formational contact from a region to the east suggests that the maximun thickness of the Sentinel Butte Formation may be nearly 26 meters thicker than previously estimated. Paleocurrent data from this area indicate a SSW flow direction. This information, combined with data from earlier studies, suggests that the source area for these sediments was not the Powder River Basin. Examination of the thicknesses of various lignite beds in the Nessen Anticline area does not reveal if the anticline served as a diversionary barier during the deposition of these strata. It is possible that the development of the anticline was more influential during late Sentinel Butte time

Analysis of Arkansas Fur Harvest Records - 1942-1984: III. Harvest-Price Relationships

Correlation and linear regression analyses between mean annual pelt price and total harvest of 13 Arkansas furbearer species between 1965 and 1983 were performed for state and regions (Ozark Mountains, Ouachita Mountains, Gulf Coastal Plain, and Mississippi Delta). Statewide, strong correlations (r \u3e 0.80) were identified for bobcat (Felis rufus), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), mink (Mustela vison), nutria (Myocastor coypus), opossum (Didelphis virginiana), and raccoon (Procyonlotor). Moderate correlations (r = 0.55 - 0.79) were identified for eastern spotted skunk (Spilogale putorius), muskrat (Ondatra zibethicus), river otter (Lutra canadensis), and striped skunk (Mephitis mephitis). Nonsignificant correlations (r \u3c 0.468) were shown for beaver (Castor canadensis) and long-tailed weasel (Mustela frenata). Regional differences were noted for each species

Barriers to Using Fixed-Route Public Transit for Older Adults, MTI Report 09-16

For older adults, unmet transportation needs are linked to reduced well-being (Cvitkovich and Wister 2001). Current research indicates that, as a society, we are ill-prepared to provide adequate transit for the growing increasing population of older adults (Millar, 2005). Although public transit is available for many older adults, actual and perceived barriers prohibit its use. Thus, the research presented here examines what do older persons perceive as barriers to using fixed-route public transit? Four focus groups were conducted with older adults in order to gain insights into what they perceive as barriers to use of fixed route transit. Findings from these focus groups informed the development of a mail-out survey sent to 1800 older adults—half each in Erie County, New York and the City of San José, California. A total of 775 (43.1%) surveys were returned. Despite concerns of response bias, data analyses reveal that older adults perceive fixed-route public transit as a viable option to their preferred mode of transit, the automobile. However, older adults note significant barriers to the use of fixed-route transit. This report summarizes findings and presents a behavior change model that may be used as an intervention and even a guide to market the strengths of fixed-route public transit while encouraging older adults to use transit