Thesis (Ph. D.)--University of Massachusetts Amherst, 2009. / Includes bibliographical references (p. 131-136). Print copy also available.

Thesis (Ph. D.)--University of Chicago, 1913. / Reprinted from the Journal of infectious diseases, vol. II, no. 3 November, 1912; vol. XIII, no. 3, November, 1913; vol. 16, no. 3, May, 1915. Includes bibliographical references (p. 422-424) Also available on the Internet.

Pseudomonas aeruginosa is known to dissimilate glucose by way of a pathway which does not involve phosphorylation at the hexose level. The established intermediates in this pathway are gluconate, 2-ketogIuconate, pyruvate and finally the compounds of an unconventional tricarboxylic acid cycle. The major gap in our knowledge concerns the fate of 2-ketogluconate. The enzymes responsible for the degradation of this compound have proven to be very unstable and previous attempts to obtain an active cell preparation or cell free extract have met with little success. There is some evidence that drying cells in an atmosphere of carbon monoxide preserves the enzyme in question while interfering with the complete oxidation of 2-ketogluconate. This should result in the accumulation of an intermediate product and thus would make possible the elucidation of one more step in the sequence of reactions. For this reason the work on monoxide-dried cells was continued in the hope, that they would serve as a source of the 2-ketogluconate enzyme. This technique produced a preparation with a good ability to oxidize 2-ketogluconate. However, the viscous nature of the preparation made centrifugal separation of the remaining live cells almost impossible. Glucose and gluconate grown cells when suspended in a 45% solution of sucrose and subjected to sonic vibrations produced a reproducible cell free preparation with a good ability to oxidize 2-ketogluconate. This preparation had an optimum pH of 7.4 and a respiratory quotient of 3. The mechanism of this oxidation remains unexplored. Pyruvic acid was identified as a product of this reaction. The crude sucrose sonicate was not stimulated by ATP and no phosphorylation could be detected aerobically or anaerobically by measuring acid stable (ester) phosphate. The preparation was not inhibited by 2.5 x 10⁻² sodium fluoride. Moreover, a crude sonicate of gluconate grown cells in the presence of ATP and magnesium, showed no phosphorylated compounds, by the chromatographic methods employed. The study for detection of phosphorylated compounds was carried out under strict anaerobic conditions. No new intermediates were isolated in the pathway of 2-ketogluconate breakdown and this pathway still remains unknown. However, this work has provided several methods of obtaining active cell preparations. / Land and Food Systems, Faculty of / Graduate

Offprints of 35 journal articles inserted / Bibliography: leaves 28-29 / 1 v. (various pagings) ; / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D. Sc.)--Dept. of Animal Science, University of Adelaide, 1985

Hydrogen oxidation by Azospirillum brasilense Sp7 was studied in N(,2)-fixing and NH(,4)('+)-grown batch cultures. The K(,m) for H(,2) of O(,2)-dependent H('3)H oxidation in whole cells was 9 uM. The rates of H('3)H and H(,2) oxidation were very similar, indicating that the initial H(,2) activation step in the overall H(,2) oxidation reaction was not rate-limiting and that H('3)H oxidation was a valid measure of H(,2)-oxidation activity. Hydrogen-oxidation activity was inhibited irreversibly by air. In N-free cultures the O(,2) optima for O(,2)-dependent H(,2) oxidation, ranging from 0.5-1.25% O(,2) depending on the phase of growth, were significantly higher than those of C(,2)H(,2) reduction, 0.15-0.35%, suggesting that the H(,2)-oxidation system may have a limited ability to aid in the protection of nitrogenase against inactivation by O(,2). Oxygen-dependent H(,2) oxidation was inhibited by NO(,2)('-), NO, CO, and C(,2)H(,2) with apparent K(,i) values of 20, 0.4, 28, and 88 uM, respectively. These inhibitors also affected methylene blue-dependent H(,2) oxidation, presumably by acting on the hydrogenase directly. The CO inhibition was easily reversible; the NO(,2)('-) and NO inhibitions were irreversible; and the C(,2)H(,2) inhibition was not readily reversible. Hydrogen-oxidation activity was 50 to 100 times higher in denitrifying cultures when the terminal electron acceptor for growth was N(,2)O rather than NO(,3)('-), possibly due to the irreversible inhibition of hydrogenase by NO(,2)('-) and NO in NO(,3)('-)-grown cultures. THe expression of the H(,2)-oxidation system was independent of nitrogenase expression, did not require added H(,2) (and probably not endogenous H(,2)), was not affected by low concentrations of carbon substrates (less than 30 mM malate), and required low O(,2) concentrations (microaerobic or anaerobic conditions).

Thesis (M.Sc. Biology)--University of Waikato, 2007. / Title from PDF cover (viewed May 2, 2008) Includes bibliographical references (p. 131-144)

Thesis (Ph. D.)--University of Wisconsin--Madison, 1963. / Typescript. Abstracted in Dissertation abstracts, v. 23 (1963) no. 9, p. 3111-2. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, December 2006. / Includes bibliographical references.

No description available.

This thesis is concerned with cellular responses to stress including the adaptive response to H2O2, and the cellular roles of sumoylation in stress responses. 286 H2O2-sensitive Saccharomyces cerevisiae deletion mutants were screened and YAP1, SKN7, GAL11, RPE1, TKL1, IDP1 were identified to be important for adaptation to H2O2. The mutants fell into two groups based on their responses to acute and chronic doses of H2O2. Transcription factors Yap1p, Skn7p and Gal11p were important for both acute and chronic responses to H2O2. Yap1p and Skn7p were needed for up-regulation of anti-oxidant functions rather than generation of NADPH or glutathione. Adaptation was reduced in strains deleted for GPX3 and YBP1, which are involved in sensing H2O2 and activating Yap1p, but to a lesser extent than YAP1 deletion. RPE1, TKL1 and IDP1 deletants affected in NADPH production were chronically sensitive to H2O2, but resistant to an acute dose and other mutants affected in NADPH generation were also affected in adaptation. These mutants overproduced reduced glutathione (GSH) but maintained normal cellular redox homeostasis. Over-production of GSH was not regulated by transcription of the gene encoding -glutamylcysteine-synthetase. The Skn7p transcription factor is therefore important for the adaptive response to oxidative stress-induced by H2O2, and NADPH generation is also required for adaptation. The roles of sumoylation in stress responses and transcriptional regulation were examined by deleting the SUMO ligases Siz1p and Siz2p. Siz1p is required for tolerance to copper ions and DNA damage repair. Siz2p is involved in repression of stress responses, particularly oxidative stress and is required for activation of nucleotide and RNA metabolism, DNA processing and cell division. Both Siz1p and Siz2p act in parallel in the repressing heat-shock responses and in reducing chronological life span. Genome-wide transcriptional analysis showed that Siz1p and Siz2p repress the mitochondrial retrograde pathway and arginine biosynthesis, while activating some carbon and nitrogen metabolism genes. Sumoylation of proteins in the wild type was induced by nitrogen starvation or mitochondrial inhibition during the initial treatment. However, nitrogen starvation led to some protein degradation, while the SUMO-conjugated proteins were recycled in cells with disrupted mitochondrial functions.