The Ins and Outs of Sleep: How Internal Metabolic and External Environmental Signals Affect the Sleep Process

The behavioral pattern of activity followed by rest (activity:rest) is an evolutionarily conserved trait. A prominent manifestation of rest in vertebrates consists of sleep, which is adaptive because a disruption of sleep by internal or external influences results in severe health outcomes such as obesity, mood disorders, cognitive impairment, and so forth. Despite the clinical imperative to understand how these cues influence sleep, the mechanisms by which they do so are still unclear. Internally, metabolic cues interact with biochemical pathways that regulate sleep amount and quality. Externally, numerous environmental cues such as light, temperature, and chemicals affect the timing of sleep behavior. The goal of this thesis is to understand the mechanisms by which one internal (the `ins\u27) and one external (the `outs\u27) cue regulates sleep behavior using Drosophila melanogaster. This work consists of two independent projects that evaluate the `ins and outs\u27 of sleep. We begin with the `ins\u27 by addressing how one metabolic enzyme GABA Transaminase (GABAT) controls energy and sleep homeostasis. GABAT is a mitochondrial enzyme found in GABAergic neurons and glial cells where it breaks down the sleep-promoting neurotransmitter, GABA, into glutamate and succinic semialdehyde, both of which can also be used for energy via the TCA cycle. In this study, we determine the mechanism by which GABAT regulates metabolic and sleep homeostasis. In our second project, we evaluate the `outs\u27 of sleep by examining an uncharacterized phenomenon whereby organisms lose their ability to maintain the circadian timing of sleep cycles in the presence of cold-temperature stress. In this project, we use wild-derived flies to evaluate the evolutionary significance of maintaining circadian cycles in some strains regardless of temperature variance, and then determine the cellular and molecular mechanism by which other strains lose their ability to drive circadian rhythms of behavior at low temperature. Overall, the work accomplished in this thesis puts us one step closer towards understanding the `ins and outs\u27 of sleep

Natural and Anthropogenic Radionuclides in Organic and Mineral Soils

In 1986 anthropogenic radionuclides were released into the atmosphere as a direct result of the nuclear reactor accident at Chernobyl. Radiocaesium deposited on the U.K has undergone a considerable amount of recycling with areas of high plant concentrations being found above soils of high organic matter content. This was contrary to the expected behaviour of radiocaesium as it was expected to fix rapidly to mineral soils and to leach rapidly from organic soils and thus be unavailable to plants and animals. This thesis examines the mobility of radiocaesium in organic rich and mineral soils from selected sites in Scotland using gamma spectroscopy and 210Pb dating in an attempt to correlate the observed behaviour with the soils properties and local topography. Laboratory methods such as adsorption/desorption isotherms are used to examine the sorption of caesium and lead in a selected range of fully characterised soils and clays in order to understand further the environmental behaviour of the radionuclides. As the behaviour of radiocaesium and other radionuclides is of interest this thesis takes both a qualitative and quantitative view of the binding of a range of metal ions to soil humic acid using techniques such as infra-red spectroscopy and potentioraetric titrations. In addition, the influence of clay/humic acid interactions upon caesium sorption are examined. The main findings of this thesis support the observed long term availability of radiocaesium in soils of high organic matter content. Radiocaesium appears to undergo lateral movement in peatlands resulting in the enrichment of layers fed by surface water run-off. Little evidence was found to support the downwards diffusion of radiocaesium in peats. The presence of humic acid in clay/humic acid systems depressed the sorption of caesium and enhanced the desorption of caesium from bentonite and kaolinite. For both sorption and desorption, the presence of humic acid resulted in lower values thus causing caesium to be more mobile

Charikleia in Context.

This is a full-length study of Charikleia, the heroine of Heliodoros' Ailhiopika. I set Charikleia in both her literary and cultural/ historical context. The thesis is divided into three chapters. In the first chapter, 1 discuss Charikleia within the genre of the Greek novel. The second chapter focuses on the issue of virginity and looks at the relationship between the Aiihiopika and early Christian literature, in particular, the Acts of Paul and Thekla. The final chapter focuses on the issue of women and education and considers the literary evidence regarding women philosophers