Insect molting and metamorphosis are regulated by two hormones, ecdysone
which causes molting and juvenile hormone (JH) which allows larval molting but prevents metamorphosis. We use both the tobacco hornworm, Manduca sexta, and Drosophila melanogaster to study: 1) the molecular basis of this unique action of JH which allows the modulation of ongoing gene expression by ecdysteroid but prevents its activation of new genes and repression of active genes; 2) the role of insulin signaling and nutrition in determining the critical size for metamorphosis. Much of our attention is currently focused on the action of JH in regulating the expression of the ecdysone-induced, pupal-specifying transcription factor Broad so as to interfere with metamorphosis. We also are studying how nutritional signals regulate the neuroendocrine signaling pathway that control metamorphosis.
An emerging theme of the laboratory in conjunction with the laboratory of Professor James Truman is the evolution of metamorphosis. We are particularly interested in how the hormonal control of embryonic development in the ancestral insects may have driven the evolution of complete metamorphosis. Therefore, we are using diverse species such as firebrats, locusts, crickets, and the milkweed bug Oncopeltus fasciatus to study the effects of JH on embryonic development and on the development of imaginal primordia. Broad is also found in these direct developing insects but here first appears in the embryo and initial experiments show that it is necessary for progressive morphogenesis during nymphal life. Therefore, we are interested in the evolution of Broad and its signaling role as a key to the evolution of metamorphosis. We are now extending our study of Broad to other arthropods and have found it in barnacles and amphipods and are currently studying its developmental expression in these two crustaceans.
magna cum laude, Radcliffe College, Biochemical Sciences, 1958
Ph.D., Cornell University, 1961