Ohio University
Athens, OH 45701
(740) 593-2275
Overview
My research is centered on cellular energetics, with a special emphasis on the metabolism of ion-transporting epithelia. As a result, my research bridges the fields of ion transport physiology and metabolic biochemistry.
Most of my research focuses on the metabolism and physiology of the insect, Manduca sexta. On-going and future research projects deal with the following three areas:
Mitochondrial Function During Insect Metamorphosis and Programmed Cell Death
Modulation of Active Ion Transport by Peptides
Midgut Acid/Base Transport
Mitochondrial Function During Insect Metamorphosis and Programmed Cell Death
Caterpillars
are essentially eating machines that eat and grow at phenomenal rates. Manduca
undergoes four larval molts and increases its mass 10,000-fold in 16 days. The
larva has a very large midgut epithelium, which is involved in digestion and
absorption of nutrients, as well as ion homeostasis. The larval midgut,
however, undergoes programmed cell death when the caterpillar
metamorphoses into a pupa. The primary area of
research in my lab is to understand how midgut mitochondrial function changes as
this tissue undergoes cell death. It is now clear from studies on
mammalian cells that early steps in programmed
cell death include depolarization of the mitochondrial membrane
potential and the release of cytochrome c into the cytoplasm. The fact that changes in mitochondrial
function occur early in programmed cell death presents an interesting dilemma
for cells. The process of
programmed cell death requires ATP, yet the organelle that generates ATP is
being altered during the cell death process. In order to understand how the
midgut cells deal with this problem, my research employs metabolic control
analysis to quantify how oxidative phosphorylation is altered during programmed
cell death. In This approach is also being used to determine if the molting
hormones, the ecdysteroids, are ultimately responsible for initiating changes in
mitochondrial function and programmed cell death in the midgut epithelium.
One important epithelial ion transport process is alkalinization of the lumen. In vivo, there is a huge pH gradient across the midgut epithelium (luminal pH = 11.3; hemolymph pH = 6.7), yet the mechanism by which the midgut transports base equivalents is unknown. Furthermore, it is not known if acid/base transport changes during development. We have established the protocol necessary for measuring in vitro acid/base transport across the midgut. In the future we will extend these studies to explore the nature of the base equivalents that are transported to the lumen and to determine if this process changes during development.
Modulation of Active Ion Transport by Peptides
In collaboration with Drs. Lee and Horodyski, also at Ohio University, we have shown that alltatropin and other neuropeptides affect midgut ion transport. Allatotropin and some FLRFamides inhibit short-circuit current and future studies will involve determining the intracellular messenger(s) that mediate the actions of these neuropeptides. Furthermore, the effects of these peptides on acid/base transport will be studied.
Chamberlin, M.E. Top-down control analysis of the effect of temperature on ectotherm oxidative phosphorylation. Am.J.Physiol. (2004) 287:R794-R800.
Chamberlin, M.E. Control of oxidative phosphorylation during insect metamorphosis. Am.J.Physiol. (2004) 287:R314-R321.
Lee, K.-Y., M.E. Chamberlin, F.M. Horodyski. Biological activity of Manduca sexta allatotropin-like peptides, predicted products of tissue-specific and developmentally regulated alternatively spliced mRNA’s. Peptides (2002) 23:1933-1941.
Woods, H.A. and M.E. Chamberlin. Effects of dietary protein concentration on L-proline transport by Manduca sexta midgut. J.Insect Physiol. (1999) 45:735-741.
Coddington, E.J. and M.E. Chamberlin. Acid/base transport across the midgut of the tobacco hornworm, Manduca sexta. J.Insect Physiol. (1999) 45:493-500.
Lee, K.-Y., F.M. Horodyski, and M.E. Chamberlin. Inhibition of midgut ion transport by allatotropin (MAS-AT) and Manduca FLRFamides in the tobacco hornworm, Manduca sexta. J.Exp.Biol. (1998) 201:3067-3074.
Chamberlin, M.E. and M.E. King. Changes in midgut active ion transport and metabolism during the fifth instar of the tobacco hornworm (Manduca sexta). J.Exp.Zool. (1998) 280:135-141.
Chamberlin, M.E. Mitochondrial arginine kinase in the midgut of the tobacco hornworm (Manduca sexta). J.Exp.Biol. (1997) 200:2789-2796.
Chamberlin, M.E., C.M. Gibellato, R.J. Noecker, and E.J. Dankoski. Changes in midgut active ion transport and metabolism during larval-larval molting in the tobacco hornworm (Manduca sexta). J.Exp.Biol. (1997) 200:643-648.
Chamberlin, M.E. Developmental changes in midgut ion transport and metabolism in the tobacco hornworm (Manduca sexta). Physiol.Zool. (1994) 67:82-94.
Gibellato, C.M. and M.E. Chamberlin. Midgut metabolism in different instars of the tobacco hornworm (Manduca sexta). J. Exp.Zool. (1994) 270:405-409.
Ballantyne, J.S. and M.E. Chamberlin. Regulation of cellular amino acid levels. In: Cellular and Molecular Physiology of Cell Volume Regulation, CRC Press, (1993), pp. 111-122.
Ballantyne, J.S., H.C. Glemet, M.E. Chamberlin and T.D. Singer. Plasma nonesterfied fatty acids of marine teleost and elasmobranch fishes. Marine Biology (1993) 116:47-52.
Chamberlin, M.E. and J.S. Ballantyne. Glutamine metabolism in elasmobranch and agnathan muscle. J.Exp.Zool. (1992) 264:267-272.
Ballantyne, J.S., M.E. Chamberlin and T.D. Singer. Oxidative metabolism in thermogenic tissues of the swordfish and mako shark. J.Exp.Zool. (1992) 261:110-114.
Chamberlin, M.E., H.C. Glemet and J.S. Ballantyne. Glutamine metabolism in a holostean fish (Amia calva) and a teleost (Salvelinus namaycush). Am.J.Physiol. (1991) 260:R159-R166.
Chamberlin, M.E. Luminal alkalinization by the isolated midgut of the tobacco hornworm (Manduca sexta). J.Exp.Biol. (1990) 150:467-471.
Chamberlin, M.E. Ion transport across the midgut of the tobacco hornworm (Manduca sexta). J.Exp.Biol. (1990) 150:425-442.
Chamberlin, M.E. and K. Strange. Anisosmotic cell volume regulation: a comparative view. Am.J Physiol. (1989) 257:C159-C173.
Chamberlin, M.E. and K.A. Jones. Inhibition of palmitoyl carnitine oxidation by 3-mercaptopropionic acid in mitochondria isolated from tobacco hornworm (Manduca sexta) midgut. Insect Biochem. (1989) 19:257-260.
Chamberlin, M.E. Metabolic stimulation of transepithelial potential difference across the midgut of the tobacco hornworm (Manduca sexta). J.Exp.Biol. (1989) 141:295-311.
Phillips, J.E., N. Audsley, R. Lechleitner, B. Thomson, J. Meredith and M. Chamberlin. Some major transport mechanisms of insect absorptive epithelia. Comp.Biochem.Physiol. (1988) 90A:643-650.
Ballantyne, J.S. and M.E. Chamberlin. Adaptation and evolution of mitochondria: osmotic and ionic considerations. Can.J Zool. (1988) 66:1028-1035.
Chamberlin, M.E. and J.E. Phillips. Effects of stimulants of electrogenic ion transport on cyclic AMP and cyclic GMP levels in the locust rectum. J Exp.Zool. (1988) 245:9-16.
Chamberlin, M.E. Enzyme activities and mitochondrial substrate oxidation in tobacco hornworm midgut. J.Comp.Physiol. (1987) 157:643-649.
Chamberlin, M.E. and L.J. Mandel. Na+-K+-ATPase activity during short-term anoxia in the thick ascending limb. Am.J.Physiol.(1987) 252:F838-F843.
Phillips, J.E. J. Hanrahan, M. Chamberlin and B. Thomson. Mechanisms and control of reabsorption of insect hindgut. Adv.Insect Physiol. (1986) 19:330-422.
Chamberlin, M.E. and L.J. Mandel. Substrate support of oxygen consumption in the medullary thick ascending limb. Am.J.Physiol. (1986) 251:F758-F763.
Murphy, E., M.E. Chamberlin and L.J. Mandel. Effects of calcitonin on cytosolic free calcium in a suspension of rabbit medullary thick ascending limb tubules. Am.J.Physiol. (1986) 251:C491-C495.
Chamberlin, M.E., A. LeFurgey and L.J. Mandel. Suspension of medullary thick ascending limb tubules from the rabbit kidney. Am.J.Physiol. (1984) 247:F955-F964.
Chamberlin, M.E. and J.E. Phillips. Oxidative metabolism in the locust rectum. J Comp.Physiol. (1983) 151:191-198.
Chamberlin, M.E. and J.E. Phillips. Regulation of hemolymph amino acid levels and active secretion of proline by Malpighian tubules of locusts. Can. J. Zool. (1982) 60:2745-2752.
Phillips, J.E., J. Meredith, J. Spring and M.E. Chamberlin. Control of ion reabsorption in locust rectum: Implications for fluid transport. J.Exp.Zool. (1982) 222:297-308.
Chamberlin,
M.E. and J.E. Phillips. Metabolic support of chloride-dependent short-circuit current
across locust recta. J.Exp.Biol. (1982) 99:349-361.
Degrees
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B.S. (highest honors), Zoology, University of California, Davis |
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Ph.D., Zoology, University of British Columbia |
Professional History
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Rush Elliott Endowed Professor |
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Associate Professor, Department of Biological Sciences,Ohio University |
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Assistant Professor, Department of Biological Sciences, Ohio University |
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Visiting Scientist, Department of Zoology, University of Guelph, Ontario, Canada |
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Research Associate, Department of Physiology, Duke University Medical Center |