Typescript. / Thesis (Ph. D.)--University of Hawaii, 1966. / Bibliography: leaves 81-83. / ix, 83 l illus., tables

Aerobacter aerogenes was shown to accumulate large quantities of a glycogen-1ike polysaccharide when grown under conditions of nitrogen deprivation and carbon excess. The majority of the reserve material was rapidly degraded during incubation in a non-nutrient medium; however, a decrease in carbohydrate to the structural level was obtained only after a four-day starvation period. Cells possessing the energy reserve compound contained a substantially reduced ribosomal complement relative to carbon-limited A. aerogenes and Pseudomonas aeruginosa which did not store this material. Ribosomes were degraded during starvation to barely detectable levels. In the non-nutrient environment, various intracellular components were degraded. Glycogen was the primary substrate for nitrogen-limited A. aerogenes, ribonucleic acid (RNA), for carbon-limited A. aerogenes and protein for nitrogen-limited P. aeruginosa. Correlating with the preferential utilization of RNA by carbon-limited A. aerogenes was the ability of this organism to oxidize ribose, one of the degradation products of RNA metabolism. P. aeruginosa was unable to degrade ribose but could efficiently oxidize most of the common amino acids and, therefore, protein was presumably the primary substrate during the endogenous metabolism of this organism. Survival curves of cells respiring endogenously revealed that glycogen-rich A. aerogeiies remained almost completely viable over a 24 hr. period of starvation whereas glycogen-deficient A. aerogenes or P. aeruginosa did not. However, once the rapid death rate of Aerobacter was initiated, the process continued until less than 1% of the original population remained viable. Conversely, although the death rate of P. aeruginosa was initially very fast, the number of viable cells at no time decreased to less than 6% of the original viable number. Alterations in the rates of transport of metabolites in A. aerogenes and P. aeruginosa did not correlate with maintenance of viability, as determined by the ability of cells to form colonies on plate count agar. It was concluded that the capacity to store a carbonaceous energy reserve is obviously a biological advantage to Aerobacter aerogenes. However, the ability of Pseudomonas aeruginosa to catabolize a wide range of substrates, coupled with the maintenance of its transport systems, must be more physiologically advantageous for the survival of a species than the ability to store carbonaceous reserves under certain limited growth conditions. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

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No description available.

Phosphate is an essential but limited macronutrient for all plants. In response to limited levels of phosphate, plants have developed highly specialized developmental, biochemical, and molecular responses. To further expand our knowledge of the phosphate starvation induced signal transduction pathway in plants, the expression of the phosphate starvation inducible Purple Acid Phosphatase 1 (PAP1) gene was studied in transgenic Arabidopsis. While few components have been identified regulating gene expression under phosphate starvation conditions in plants, one cis regulatory element recognized by the MYB transcriptions factor Phosphate Starvation Response 1 (PHR1) has been identified in many phosphate starvation induced (PSI) genes. PAP1 and many other genes examined during the course of the mutant characterization contain this cis element. Using the GUS reporter gene under control of the PAP1 promoter, a mutant screen was devised for plants showing abnormal PAP1 response to phosphate nutrition. Three mutant lines were identified and subsequently characterized for the phosphate starvation-induced signal-transduction pathway in Arabidopsis. Two mutants, BT1 and BT2, both with dominant mutations, showed increased GUS staining. The mutations in BT1 and BT2 are tightly linked to the transgene and to each other, but complementation analysis suggested that they are in different genes. Characterization of these mutants indicated that the PSI genes PAP1 and At4 (in BT1 roots), and RNS1 (in BT2 leaves) have alternative or additional methods of regulation other than PHR, even though these genes all contain PHR1 binding sites. A third mutant, BT3, had a phenotype similar to the PAP1 null-mutant and did not show PAP1 phosphatase activity under normal soil-grown conditions. Characterization of BT3 indicates that PAP1, RNS1, and AtIPS1 are not exclusively regulated by PHR1. In an attempt to map the BT3 mutant in a Columbia background by crossing with Landsberg erecta (Ler), it was discovered that the Ler ecotype does not show PAP1 phosphatase activity under normal soil-grown conditions. The PAP1 phosphatase regulatory trait, named BT5, was mapped to a 15,562 bp-region area containing only two genes between the GPA1 and ER markers on Chromosome 2.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vii, 93 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

The femoral arterial blood flow in sheep was determined by implanting Doppler cuffs around the vessel which facilitated measurements over a prolonged period of time. Standardization of the cuffs was accomplished with an electronic integrator-digital time counter which converted Doppler frequency shifts to counts per mV/hr from which blood flow was estimated. Metabolic changes occurring in the hind limb of sheep following starvation were studied using femoral arterio-venous concentration differences of metabolites coupled with blood flow. Indwelling catheters were introduced into the femoral artery and vein to enable blood sampling. Two series of experiments were carried out in this study. Experiment I involved a four day starvation of two ewes. There was no statistical difference in the femoral arterial blood flow between fed and starved animals. In Experiment II another animal was utilized for four trials with the duration of starvation increased from four to six days. The adjusted mean fed blood flow of 78 + 2 ml/min decreased to a minimum of 45 + 3 ml/min on the sixth day of starvation. The average blood flow during the six days of starvation was 23.5 per cent lower than the pre-starvation level (P 0.05). The Doppler Flowmeter offers definite advantages over other methods of blood flow determinations by facilitating the measurement over prolonged periods without causing excitement of the animals. In this study the use of the Doppler Flowmeter and the continuous monitoring of blood flow through a period of 11 days has demonstrated that hind limb blood flow is reduced during starvation. The utilization of glucose and lactate was reduced during starvation by 62 and 39% respectively. There was a net production of 25 ± 1.5 and 20 ± 1 pg/min of alanine on the fifth and sixth days of starvation versus a net utilization of 23 ± 2 pig/min prior to starvation. The net alanine production during starvation provides a precursor for gluconeogenesis. / Land and Food Systems, Faculty of / Graduate

Identification of patients with suboptimal nutritional status allows for early treatment intervention. Currently, no definitive test of nutritional status exists. Therefore, this study was conducted to identify possible functional indicators of acute nutritional deprivation. The effects of total nutritional deprivation and subsequent refeeding on lymphocyte functions and subpopulations were examined in 23 healthy cats. Peripheral blood samples were analyzed at various times during fasting and refeeding periods. During the fasting period, decreases were observed in leukocyte number (day 4; p < 0.04), lymphocyte number (p < 0.02), CD4+ cells (day 4; p < 0.06), CD4:CD8 ratio (0 hours; p < 0.004), and mitogen stimulated CD4:CD8 ratio (72 hours; p < 0.15) during the fasting period as compared to baseline. Increases were seen in CD4+ cells (day 7; p < 0.09), CD8+ cells (day 7; p < 0.04) and intracellular calcium (day 4; p < 0.02) as compared to baseline. During the refeeding period increases (p < 0.05) were observed in leukocyte number, CD4+ cells, CD8+ cells, lymphocyte proliferation (p < 0.07) and lymphocyte number (p < 0.004) as compared to day 7. These findings suggest that 7 days starvation had immunosuppressive effects on cats which were alleviated during 7 days refeeding. The use of CD4:CD8 ratio in conjunction with intracellular calcium flux may be useful as indices of nutritional status. / Master of Science

Chlamydia trachomatis is a Gram-negative, obligate intracellular pathogen that is the causative agent of sexually transmitted infections and the ocular disease trachoma. Chlamydia trachomatis undergoes a biphasic developmental cycle differentiating between the infectious elementary body (EB) and the replicative reticulate body (RB). Under certain stress conditions, C. trachomatis can stall its developmental cycle and enter an aberrant state termed persistence. While in a persistent state, C. trachomatis is refractory toward antibiotics, can evade the host immune response, and becomes undetectable using standard clinical detection methods. Environmental and other pathogenic microbes are known to utilize partner switching mechanisms (PSM) to regulate sigma factors used to initiate a stress response. For this reason, this study focuses on the chlamydial PSM, its role in regulating the availability of the housekeeping sigma factor σ66, and its role in the developmental cycle and stress response of C. trachomatis. The chlamydial PSM is composed of five known proteins: the anti-sigma factor RsbW, two anti-anti-sigma factors RsbV1 and RsbV2, a regulatory phosphatase RsbU, and a second phosphatase-like protein CTL0852. In order to test the role of the PSM in the chlamydial stress response, a panel of C. trachomatis rsbV1 mutants were generated, persistence inducing iron starvation and tryptophan starvation cell culture conditions were optimized, and growth of the rsbV1 mutants under iron starvation conditions were assayed. No significant differences were seen between rsbV1 mutants under iron starvation nor recovery conditions as determined by progeny production and inclusion size analysis. Furthermore, this study generated PSM protein producing Escherichia coli strains for in vitro protein work and performed operon mapping of the PSM genes of C. trachomatis to help aid in future studies of the chlamydial PSM by facilitating the development of new chlamydial PSM mutants. This study gives phylogenetic support to the classification of ctl0852 as a chlamydial PSM gene by comparing relative mutations rates of PSM genes across chlamydial species.