Life Sciences Commons^™

Thermotrophy Exploratory Study, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

The question of whether environmental heat energy could be utilized as a source of energy for biological metabolism is the center of this exploratory research. In 1979, this author postulated a hypothesis for the existence of thermotrophs that could isothermally utilize environmental heat energy as a source of their energy on Earth. According to this hypothesis, the thermotrophs could be the first primitive forms of life in the early Earth environment. The chemotrophs and phototrophs that we currently are all well familiar with might have been evolved somehow from the primitive thermotrophs. Furthermore, all the organisms currently regarded as the …

Can Lactate Dehydrogenase Be Used To Index Anaerobic Activity In Fishes?, Casey W. Schoenebeck, Erik Prenosil, Brianna Pallas, Aspen Abrams, Kimberly Carlson

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

Anaerobic activities such as those associated with spawning, foraging for prey, and predator avoidance are difficult to quantify in wild fish. This study experimentally evaluated if the muscle enzyme lactate dehydrogenase (LDH) can be used to index recent anaerobic activity in fish by testing the hypothesis that muscle LDH activity will be greater in exercised fish than in rested fish. We used burst swimming motions in a swim tunnel to elicit anaerobic metabolism in a 5 day anaerobic exercise treatment (n = 30) and a rested control group (n = 30). On average the exercised fish produced significantly more LDH …

Functional Characterization Of Aggregatibacter Actinomycetemcomitans Qsebc : A Bacterial Adrengeric Receptor And Global Regulator Of Virulence., Whitney Weigel

Electronic Theses and Dissertations

In order for a pathogen to successfully colonize the host, it must be able to acquire essential nutrients and regulate gene expression to respond to environmental fluctuations. One mechanism bacteria have evolved in order to detect these fluctuations and respond is the two component signal transduction systems (TCS). Aggregatibacter actinomycetemcomitans, a dental commensal associated with localized aggressive periodontitis, contains a TCS designated QseBC that was previously shown to regulate expression of several iron acquisition genes, biofilm formation and virulence, but the activating signal was unknown []. QseBC is a conserved TCS in the Enterobacteriaceae and Pasteurellaceae, but the activating signal …

Changes In Microbial Communities Along Redox Gradients In Polygonized Arctic Wet Tundra Soils, David A. Lipson, Ted K. Raab, Melanie Parker, Scott T. Kelley, Colin J. Brislawn, Janet Jansson

Ted K. Raab

This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the Arctic Coastal Plain in northern Alaska, and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced Fe to total Fe in acid extracts as a proxy): conditions grew more reducing with depth and were …

Ionic Liquid Extraction Unveils Previously Occluded Humicbound Iron In Peat Porewater, Timothy J. Veverica

Dissertations, Master's Theses and Master's Reports - Open

Extracellular iron reduction has been suggested as a candidate metabolic pathway that may explain a large proportion of carbon respiration in temperate peatlands. However, the o-phenanthroline colorimetric method commonly employed to quantitate iron and partition between redox species is known to be unreliable in the presence of humic and fulvic acids, both of which represent a considerable proportion of peatland dissolved organic matter. We propose ionic liquid extraction as a more accurate iron quantitation and redox speciation method in humic-rich peat porewater. We evaluated both o-phenanthroline and ionic liquid extraction in four distinct peatland systems spanning a gradient of physico-chemical …

Evidence Supporting Dissimilatory And Assimilatory Lignin Degradation In Enterobacter Lignolyticus Scf1, Kristen Deangelis, Deepak Sharma, Rebecca Varney, Blake Simmons, Nancy G. Isern, Lye Meng Markillie, Carrie Nicora, Angela D. Norbeck, Ronald C. Taylor, Joshua T. Aldrich, Errol W. Robinson

Microbiology Department Faculty Publication Series

Lignocellulosic biofuels are promising as sustainable alternative fuels, but lignin inhibits access of enzymes to cellulose, and by-products of lignin degradation can be toxic to cells. The fast growth, high efficiency and specificity of enzymes employed in the anaerobic litter deconstruction carried out by tropical soil bacteria make these organisms useful templates for improving biofuel production. The facultative anaerobe Enterobacter lignolyticus SCF1 was initially cultivated from Cloud Forest soils in the Luquillo Experimental Forest in Puerto Rico, based on anaerobic growth on lignin as sole carbon source. The source of the isolate was tropical forest soils that decompose litter rapidly …

The Effect Of Cadmium Exposure On Repeat Swimming Performance And Recovery In Rainbow Trout (Oncorhynchus Mykiss), Brown Trout (Salmo Trutta) And Lake Whitefish (Coregonus Clupeaformis), Jessie L. Cunningham

Theses and Dissertations (Comprehensive)

Swim performance provides a measure of the integrated metabolic costs of sub-lethal exposure to stressors, including Cd. While the impacts to sustained swimming performance in Cd exposed fish have already been characterised, effects to repeat swimming ability have not. This thesis identifies the effects of sub-lethal waterborne Cd exposure on ionoregulatory function, repeat swimming ability, anaerobic metabolism and stress response in rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and lake whitefish (Coregonus clupeaformis).

Repeat swim trials included an initial swim to 85% of the U_crit of control fish and a recovery period …

Effects Of Long-Term Hypoxia On Enzymes Of Carbohydrate Metabolism In The Gulf Killifish, Fundulus Grandis, Mery L. Mártinez, Christie Landry, Ryan Boehm, Steve Manning, Bernard B. Rees

Faculty Publications

The goal of the current study was to generate a comprehensive, multi-tissue perspective of the effects of chronic hypoxic exposure on carbohydrate metabolism in the Gulf killifish Fundulus grandis. Fish were held at approximately 1.3 mg l(-1) dissolved oxygen (similar to 3.6 kPa) for 4 weeks, after which maximal activities were measured for all glycolytic enzymes in four tissues (white skeletal muscle, liver, heart and brain), as well as for enzymes of glycogen metabolism (in muscle and liver) and gluconeogenesis (in liver). The specific activities of enzymes of glycolysis and glycogen metabolism were strongly suppressed by hypoxia in white skeletal …

Temperature Tolerance In Crustaceans: Critical Temperatures And The Heart, Lindsay Haupt (Murray-Miller)

All Theses And Dissertations

At certain upper and lower threshold temperatures (critical temperatures (Tc) crustaceans switch to anaerobic metabolism despite sufficient oxygen availability in the environment. I tested the hypothesis that failure of the heart at critical temperatures leads to insufficient oxygen delivery and subsequent anaerobiosis in peripheral tissues.

I exposed rock crabs, Cancer irroratus, as whole animals, and their buffer-perfused semi-isolated hearts to a progressive temperature increase, while monitoring heart rate and lactate accumulation. The whole animals heart rate increased with temperature following a Q₁₀ of 2.8. An abrupt decline in heart rate occurred at 25°C and lactate accumulation occurred between …