Copy of author's previously published work inserted. / Includes bibliographical references (leaves 160-182). / xi, 182 leaves, [57] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Concentrates mainly on the characterisation of the molecular mechanism of action of the tec protein tyrosine kinase using biochemical and genetic approaches. / Thesis (Ph.D.)--University of Adelaide, Dept. of Molecular Biosciences, 2001?

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No description available.

LD2668 .T4 1947 K4 / Master of Science

Life relies on the integration of external environmental stimuli and internal signals to balance fluctuations in nutrient availability to achieve homeostasis. Bone has recently emerged as a pleiotropic endocrine organ that secretes at least two hormones, FGF23 and osteocalcin, which regulate kidney function and glucose homeostasis, respectively. These findings have raised the question of whether other bone-derived hormones exist and what their potential functions are. Here we identify, through molecular and genetic analyses in mice, lipocalin 2 (LCN2) as an osteoblast-enriched, secreted protein. Loss- and gain-of-function experiments in mice demonstrate that osteoblast-derived LCN2 maintains glucose homeostasis by inducing insulin secretion and improves glucose tolerance and insulin sensitivity. In addition, osteoblast-derived LCN2 inhibits food intake. LCN2 crosses the blood–brain barrier, binds to the melanocortin 4 receptor (MC4R) in the paraventricular and ventromedial neurons of the hypothalamus and activates an MC4R-dependent anorexigenic (appetite-suppressing) pathway. These results identify LCN2 as a bone-derived hormone with metabolic regulatory effects, which suppresses appetite in a MC4R-dependent manner, and show that the control of appetite is an endocrine function of bone. Furthermore, we show that serum LCN2 levels correlate with insulin levels and β-cell function, indices of healthy glucose metabolism, in genetic and diet-induced mouse models of obesity and in obese, healthy or pre-diabetic patients. However, LCN2 serum levels also correlate with body mass index (BMI) and insulin resistance in the same patients; and are increased in obese mice. To dissect this apparent discrepancy, we examined LCN2 effects in hyperphagia and β -cell function mouse models of obesity or β -cell destruction. Silencing Lcn2 expression increases hyperphagia, fat and body weight and worsens β -cell function and general metabolic dysfunction in obese, leptin receptor-deficient mice. Conversely, LCN2 increases β-cell numbers and promotes β-cell function after streptozotocin-induced β -cell failure by (STZ) and acts as a growth factor necessary for β -cell adaptation to higher metabolic load in mice. These results support a protective role for LCN2 in obesity-induced glucose intolerance and insulin resistance that stem from its ability to decrease food intake and promote adaptive β-cell proliferation.

The overall objective of this thesis was to test the hypothesis that maternal overnutrition has adverse effects on the expression of central metabolic regulators in offspring but could be offset by supplementing green tea extract (GTE) to the dams during gestation and/or lactation. This thesis focuses on two aspects of central metabolic regulation: the leptin signaling that links to appetite regulation and the sirtuin 1(SIRT1)/oxidative stress pathway that links to insulin sensitivity (IS). This study was initiated based on previous findings of this laboratory that via developmental programming energy intake of offspring born to dams given GTE during lactation was suppressed and that IS was improved in offspring of dams supplemented with GTE during gestation and/or lactation. The diets used included low fat (LF), high-fat (HF), and HF diet added with 0.75% or 1%GTE (GT1, GT2). In experiment 1, female rats were given the respective diet 8 weeks prior to mating till the end of lactation. Male offspring were weaned to the HF, GT1 or GT2 diet for 10 weeks forming the LF/HF, HF/HF, GT1/HF, GT2/HF, HF/GT1 and HF/GT2 groups. Maternal and postweaning GTE supplementation increased hypothalamic leptin receptor (OB-Rb) and signal transducer activator of transcription 3 (STAT3) mRNA suggestive of enhanced leptin signaling but pro-opiomelanocortin (POMC) mRNA expression, an appetite inhibitor was only elevated in the HF/GT1 group which was associated with reduction in food intake in this group. Central oxidative status was improved in GT1/HF and GT2/HF offspring through enhanced hypothalamic SIRT1 and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) expression compared with the HF/HF group. These improvements coincided with better IS in the HF offspring born of GTE supplemented dams. Experiment 2 was designed to determine the relative importance of gestation and lactation as the critical period for GTE supplementation. Female rats were assigned to LF, HF or GT1 diet 9 weeks prior to mating till the end of pregnancy. During lactation half of the HF and GT1 dams had the diet switched to GT1 and HF, respectively. Male offspring were fed the LF or HF diet until 22 weeks of age forming 10 offspring groups: LF/LF/LF, LF/LF/HF, HF/HF/LF, HF/HF/HF, HF/GT1/LF, HF/GT1/HF, GT1/HF/LF, GT1/HF/HF, GT1/GT1/LF, and GT1/GT1/HF. Consistent with a reduction in energy intake in offspring born to dams receiving GTE supplementation during lactation, there was an increase in melanocortin 4 receptor (MC4R) expression in the hypothalamus (P<0.05). Regardless of postweaning diet, offspring of dams given GTE during gestation and/or lactation had elevated hypothalamic PGC-1α and reduced protein phosphorylation of c-Jun N-terminal kinase-1 when compared with offspring of unsupplemented dams(P<0.05) which was associated with improved IS. Hence, leptin signaling and appetite regulators in the offspring were selectively affected by GTE supplementation during lactation whereas offspring exhibited improved ability to handle oxidative stress if dams received GTE supplementation during gestation and/or lactation. Collectively, these results support the notion that central mechanisms with roles in appetite control and oxidative status are susceptible to the programming phenomenon triggered by maternal nutritional status. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

Batch cultures of Candidatus Pelagibacter ubique were grown under iron-, organosulfur-, and nitrogen-limiting conditions to understand how this ubiquitous marine bacterium responds to and interacts with environments where growth is limited by the availability of these nutrients. Global gene expression was monitored using microarrays and quantitative mass spectrometry to observe both transcriptional and post-transcriptional responses to nutrient limitation. Iron- and nitrogen-limited cultures were characterized by increased transcription and translation of transporters involved in acquisition of the limiting nutrient, whereas organosulfur-limited cultures were not. Methionine synthesis genes downstream of S-adenosyl methionine riboswitches were up-regulated in mRNA and protein during organosulfur-replete stationary phase. Comparative genomics also revealed Ca. Pelagibacter to be the only genus among the free-living Alphaproteobacteria to lack a P[subscript II]-mediated nitrogen regulatory pathway – a pathway which may be complemented in Ca. P. ubique by putative riboswitches and a citric acid cycle able to bypass the glutamate precursor 2-oxoglutarate. Overall, the results of this study provide insight into the regulatory and metabolic processes of this ecologically significant organism, and enable better interpretation of metatranscriptomic and meta-proteomic surveys by identifying sfuC and amtB as likely biomarkers for iron and nitrogen limitation, respectively, in natural Ca. P. ubique populations. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Dec. 13, 2011 - Dec. 13, 2013

Seven genes involved in metabolism were tested as direct targets of the Notch signalling pathway. For each gene the occupancy of its enhancers by Su(H), its transcriptional response to Notch pathway and its biological functionality was verified in vitro and in vivo.

Opioid/adrenergic interactions were studied to evaluate two hypotheses: (1) naloxone potentiates the effect of epinephrine on cardiac contractility by increasing circulating epinephrine concentrations; and (2) endogenous and exogenous opioids alter left cardiac nerve stimulationinduced norepinephrine release and cardiac function. A canine isolated heart-lung preparation was used for the first study. Plasma epinephrine was determined and myocardial epinephrine uptake was calculated during intravenous epinephrine infusion. Naloxone (4 mg) was given and the epinephrine infusion was repeated. Naloxone increased cardiac contractility, coronary blood flow, and the coronary sinus epinephrine concentration. When coronary blood flow was subsequently held constant (100% above resting), naloxone increased only contractility. This result indicated that the previously observed increase in coronary sinus epinephrine was flow dependent. Corticosterone (an uptake II blocker) was employed as a positive control. Corticosterone increased the contractile response to epinephrine, but unlike naloxone, corticosterone was accompanied by a clear decrease in myocardial epinephrine uptake. The stereospecificity of the response to naloxone was investigated and (+) naloxone equaled or exceeded (-) naloxone in potentiating the inotropic effect of epinephrine. In the second study, the left cardiac nerve was isolated and electrically stimulated in intact dogs. Norepinephrine overflow gradually declined during successive control stimulations. Pretreatment with naloxone (100 Mg/kg) prevented or delayed the decline. An intracoronary dynorphin 1-9 infusion (2 nmol/min/kg for 20 minutes) reduced both norepinephrine overflow and cardiac performance, and both effects were prevented by pretreatment with naloxone (100 /xg/kg) . To summarize, naloxone potentiated the inotropic effect of infused epinephrine without altering circulating epinephrine concentrations or myocardial epinephrine uptake. This effect of naloxone was not stereospecific and probably not mediated through a traditional opiate receptor. Endogenous and exogenous opioids inhibited the left cardiac nerve stimulation-induced norepinephrine overflow, suggesting that opiate receptors may regulate cardiac excitability by modulating norepinephrine release.

The temperature-dependent catalytic activity of rat liver 3-hydroxy-3 -methylglutaryl coenzyme A reductase (HMG-CoA reductase) displays the nonlinear Arrhenius behavior characteristic of many membrane-bound enzymes. A two-conformer equilibrium model has been developed to characterize this behavior. In the model, HMG-CoA reductase undergoes a conformational change from a low specific activity to a high specific activity form. This conformation change is apparently driven by a temperature-dependent phase transition of the membrane lipids. It has been found that this model accurately describes the data from diets including rat chow, low-fat, high-carbohydrate, and diets supplemented with fat, cholesterol or cholestyramine. The effects characterized by the model are consistent with the regulation of HMG-CoA reductase by enzyme-lipid interactions.