Truman, J.W.; University of Washington: Insect Ecdysis: dissection of an endocrine cascade that underlies a complex program of behavior.

Natural behaviors are often organized into discrete phases that have to be performed in a specific sequence if they are to be of adaptive value. Studies on simple networks, like the stomatogastric ganglion of lobsters, show that neuroendocrine signals play a key role in configuring these networks into discrete functional states. At the level of whole animal behavior, one would then like to know if distinct neuroendocrine signals are associated with each behavioral phase. If so, what is the organization of the neuroendocrine circuitry and how is it related to behavioral organization and to sign stimuli that normally shift the animal from one behavioral phase to the next. We have been exploring these issues using insect ecdysis behavior, the stereotyped behavioral sequence used by an insect as it casts off its old cuticle and expands and hardens a new one. During the past 7 years studies from a number of labs have revealed that the ecdysis sequence is orchestrated through the regulated release of a series of hormones, and that the complexity of this hormonal network matches the complexity of behaviors that are displayed. Relying heavily on our recent work in Drosophila, I will describe physiological and genetic approaches that we are taking to identify new components in this control pathway and to dissect how regulatory interactions are modified as insects change form during metamorphosis. Finally, I will discuss how some of the modulatory strategies illustrated by ecdysis might be generalized to other behavioral systems.