Gibbens, Ying Ye2010-11-052010-11-052010-08https://hdl.handle.net/11299/96237University of Minnesota Ph.D. dissertation. Major: Molecular, Cellular, Developmental Biology and Genetics. Advisor: Michael B. O’Connor. 1 computer file (PDF); vii, 167 pages, Ill., (some col.).In insects, the timing of metamorphosis is modulated by a large titer of the steroid hormone ecdysone produced by the prothoracic gland. However, the molecular mechanisms that control production of the ecdysone titer are not completely understood. Here we show that blocking Activin signaling in Drosophila prothoracic gland causes developmental arrest prior to metamorphosis. This defect is due to the absence of the ecdysone titer, a likely consequence of reduced expression of the ecdysone biosynthetic enzymes. We further demonstrate that Activin signaling may regulate the competence of the prothoracic gland to respond to prothoracicotropic hormone and insulin, two hormonal signals that have been shown to trigger ecdysone synthesis. These findings suggest that Activin signaling is required for insect metamorphosis by providing competence that allows tissue- and stage-specific response to metamorphic stimuli.en-USActivinCompetenceEcdysoneInsulin signalingMetamorphosisProthoracic glandMolecular, Cellular, Developmental Biology and GeneticsThesis or Dissertation