xiii, 56 p. : ill. (some col.) / Correct regulation of insulin/insulin-like growth factor signaling (IIS) is essential for proper development and growth. More recently, proper regulation of IIS has been shown to be important for adaptation and survival under stressful conditions. Despite the importance of IIS, the mechanism underlying IIS regulation under various environmental stresses remains to be elucidated. One mechanism of regulating IIS involves the binding of insulin and insulin-like growth factors by insulin-like growth factor binding proteins (IGFBPs), which prevent the factors from interacting with the insulin receptor (InR). The only identified IGFBP in <italic>Drosophila</italic> to date is imaginal morphogenesis protein late 2 (Imp-L2), which was previously implicated in the regulation of IIS during starvation. Here, we investigate whether Imp-L2 is required to regulate IIS under low oxygen stress (hypoxia). The ability to tolerate hypoxia requires cellular adaptations that decrease the need for oxygen and increase the supply of it. In a wide variety of organisms many of these adaptations are either directly or indirectly regulated by the transcription factor hypoxia-inducible factor-1 (HIF-1). Our results reveal a regulatory link between HIF-1, Imp-L2, and IIS during hypoxia. We demonstrate that Imp-L2 transcript abundance is increased during hypoxia in a HIF-1 dependent manner resulting in inhibition of IIS and increased hypoxia tolerance. This dissertation includes unpublished co-authored material. / Committee in charge: Dr. Victoria Herman, Chairperson; Dr. Eric Johnson, Advisor; Dr. Bruce Bowerman, Member; Dr. Christopher Doe, Member; Dr. Kenneth Prehoda, Outside Member

The main aim of this thesis is to investigate the role of Impl2 gene in the regulation of immune response to bacterial infection in Drosophila melanogaster. The theoretical part provides a conceptual background concerning immunity in drosophila and also it summarizes what is known about the Impl2 gene. In the practical part, the function of Impl2 gene during infection is examined, starting with the location of its production during immune response, the changes of Impl2 gene amount during infection and its essentiality for a proper immune response. Furthermore, it examines the metabolic changes underlying an immune activation in connection to Impl2 gene. Last but not least, it tests how Impl2 gene is connected with the mobilization of energy during Chill Coma Recovery assay.