Mary E. Chamberlin, Ph.D.

     My research interests are centered on cellular bioenergetics with current emphases in two areas: 1) regulation of insect mitochondrial metabolism and 2) the developmental changes in insect ion-transporting epithelia.

     Regulation of Mitochondrial Metabolism. Mitochondria produce most of the ATP in animal cells, but not all mitochondria are alike. Mitochondria isolated from homologous tissues  in different animals or different tissues in the same animal may be functionally distinct.  Furthermore, factors such as temperature or the animal's developmental status or age affect mitochondrial function. My research is focused on the mitochondrial metabolism of the larval (tobacco hornworm) and adult (Carolina sphinx moth) stages of the lepidopteran insect, Manduca sexta. Each of these two developmental stages has a large, highly aerobic tissue from which it is possible to isolate and study mitochondria. In the larval stage (caterpillar), there is a large midgut, which digests food and engages in high rates of solute transport.  These processes are dependent on aerobic metabolism and the midgut is a mitochondria-rich tissue. The moth, on the other hand, eats very little, but flies a great deal. In insects, flight is absolutely dependent on aerobic metabolism and the flight muscle is tightly packed with mitochondria. The midgut and the flight muscle differ, however, in their normal thermal regime as well as their fate. Because the caterpillar is an ectotherm and the moth is a regional (flight muscle) endotherm, the mitochondria from these two tissues normally operate at different temperatures.  In addition, these two tissues have different destinies: the midgut is destroyed by programmed cell death, whereas the flight muscle of the moth simply senesces. My current research focuses on these two insect tissues in order to determine how oxidative metabolism is designed to operate at different temperatures and how mitochondrial function is altered during development and aging.

     Changes in Epithelial Ion Transport and Metabolism. The midgut changes throughout the growth and development of insects. The caterpillar midgut epithelium increases in cell number at every larval-larval molt and, during the preparation for metamorphosis, the larval midgut is destroyed and replaced by a pupal epithelium. An important aspect of my research involves studying the changes in midgut metabolism and active ion transport during larval growth and development. Studies underway are examining the hormonal modulation of in vitro epithelial active ion transport,  changes in midgut intermediary metabolism and antioxidant defense systems, and the processes underlying the programmed cell death of the midgut.

Selected References:

• Woods, H.A. and M.E. Chamberlin. (1999) Effects of dietary protein concentration on L-proline transport by Manduca sexta midgut. J.Insect Physiol. 45:735-741.

• Coddington, E.J. and M.E. Chamberlin (1999).  Acid/base transport across the midgut of the tobacco hornworm, Manduca sexta. J.Insect Physiol. 45:493-500.

• Lee, K.-Y., F.M. Horodyski, and M.E. Chamberlin (1998). Inhibition of midgut ion transport by allatotropin (MAS-AT) and Manduca FLRFamides in the tobacco hornworm, Manduca sexta. J. Exp. Biol. 201: 3067-3074

• Chamberlin, M.E. and M.E. King (1998). Changes in midgut active ion transport and metabolism during the fifth instar of the tobacco hornworm (Manduca sexta). J.Exp.Zool. 280:135-141.

• Chamberlin, M.E. (1997) Mitochondrial arginine kinase in the midgut of the tobacco hornworm (Manduca sexta).   J. Exp. Biol. 200:2789-2796.

• Chamberlin, M.E., C.M. Gibellato, R.J. Noecker, and E.J. Dankoski (1997). Changes in midgut active ion transport and metabolism during larval-larval molting in the tobacco hornworm (Manduca sexta). J.Exp.Biol. 200:643-648