Education:
PhD Biology – Northwestern University, Evanston, 1978
M.S. Entomology – University of California, Davis, 1972
B.S. Entomology – University of California, Davis, 1970

Research Interests:
Insect metamorphosis and reproduction is the result of an exquisite interplay between genes, hormones, physiology and abiotic factors. Integrating these processes are small acyclic sesquiterpenoid molecules, the juvenile hormones (JHs). The central role of JH in orchestrating the insect life cycle and reproductive events has not gone unnoticed among agroecologists, chemists, and entomologists who are concerned with developing better strategies for insect pest management. That we know almost nothing about the molecular mode of action of this family of hormones and synthetic agonists poses serious questions about the use of these unique molecules. Thus, it is crucial that we decipher the molecular action of the hormone before further expanding the use of the JH agonists in pest management.

To better understand the action of JH at the molecular level, we have taken several approaches. Discovery that a JH specific hemolymph transport protein (hJHBP) is positively regulated by JH suggested a model in which to study the molecular actions ofthe hormone. The gene structure ofhJHBP as well as flanking regions was elucidated. Promoter analysis probing the 5′ upstream region of the hJHBP gene as well as regions in the first intron indicated that control of hJHBP expression is complex. (NIH,USDA funding). Our inability to clearly delineate promoters led us to shift our attention towards more tractable models. We identified a JH-regulated gene critical to a cyclic AMP (cAMP) activated signal transduction pathway in Drosophila S2 cells. This gene, Epac, (Exchange Protein directly Activated by cAMP) regulates cell shape, movement and cell-cell adhesion and is consistent with the known morphostatic actions of JH in insects.

We are now in a position to examine the initial events in JH regulation of gene expression focusing on a problem that has long baffled insect endocrinologists ­ a JH receptor (Hatch funding). The goals of our present research are: (1) isolate and characterize the JH receptor (JHR) from Drosophila S2 cells. (2) Clone and express recombinant JHR (rJHR) to examine binding pocket dimensions. Perform pull-down experiments with the immobilized rJHR to catalog proteins that potentially interact with the receptor. (3) Characterize the JHR in vivo. Discovery and characterization of this receptor will be of exceptional importance for several reasons. It has been a long­ held concept that development of a JH antagonist would be an excellent candidate for control of larval pests by specifically blocking the hormone receptor site thereby forcing the insect to develop prematurely. By developing a molecular model of the receptor’s binding site, the development of more potent antagonists as well as agonists may be achieved. Understanding these associations will unlock the enigma of JH action and provide new molecular targets that can be disrupted in an environmentally sound fashion.

Research Category: Suborganismal