Endocrine Control of Imaginal Disk Growth

Duke University, Durham NC

Investigators

Abstract

The imaginal disks of insects are tissues that grow internally during larval life and that will transform into the eyes, wings, legs, mouthparts and genitalia of the adult insect during metamorphosis. The mechanisms that control the growth and development of imaginal disks are the subject of extensive investigation by developmental biologists. A new growth factor has been discovered that regulates the growth of wing imaginal disks. Evidence has been obtained that this factor is the neurohormone bombyxin, a member of the family of insulin-like proteins. Bombyxin acts together with the steroid hormone ecdysone, to induce normal growth in cultured wing imaginal disks. In normal life, the level of this growth factor in the blood depends on the amount of food intake, and it appears to be part of the mechanism by which the growth of internal tissues is coordinated with overall body growth and nutrition. The proposed work will clone and sequence the genes for bombyxin, and study the relative roles of bombyxin and ecdysone in the regulation of cell growth and cell division. In addition, studies will be done to elucidate the mechanisms by which variation in nutrition causes changes in the blood-level of bombyxin and ecdysone, and how variation in the level of these hormones in turn regulate normal growth and development. Because bombyxin is a member of the insulin family, this research will help shed light on the roles these important hormones play in regulating the relative growth of different body parts, and will enhance our understanding of how insulin regulates growth in response to variation in nutrition. This research will also support the training and education of graduate and undergraduates students.