Michael A. Wells
Regents Professor Emeritus of Biochemistry
Ph.D. 1965, University of Kentucky

Laboratory Homepage

We combine biochemical, physiological and molecular biological approaches in the study of insects. Our major experimental insects are the tobacco hornworm, Manduca sexta and the yellow fever mosquito Aedes aegypti.

Regulation of trypsin synthesis in the midgut of Aedes aegypti following a blood meal.

The conversion of protein from a blood meal into yolk proteins and lipids for the developing oocytes is an essential part of the reproductive cycle. Blood feeding by a female Aedes aegypti mosquito initiates a series of events in the midgut, the fat body and the ovaries. Female mosquitoes ingest more than their own weight in blood in a short time and then spend the next 36 hours converting the amino acids from the blood proteins into the constituents of their eggs. The regulation of digestive enzyme synthesis in the midgut occurs in two phases. The early phase begins immediately after ingestion of the meal and involves activation of translation. The synthesis of early trypsin serves as a model for this phase. The late phase begins 6-8 hours after the meal and involves activation of transcription. The synthesis of late trypsin serves as a model for this phase.

Working Hypothesis:

• In the first 30 minutes, in addition to the midgut filling, a peptide or small molecule is present in whole body extracts, which makes an in vitro midgut preparation competent for early trypsin translation. After 30 minutes, a phosphorylation cascade is initiated in the midgut which leads to activation of translation of early trypsin.
• About 6 hours after feeding, late trypsin transcription in the midgut is initiated. We have recently found that ecdysone, and an uncharacterized factor present in extracts prepared from fat bodies of fed mosquitoes, are involved in late trypsin gene induction.

Regulation of amino acid metabolism in mosquitoes

• We have been studying how the female mosquito partitions blood protein amino acids between synthesis of energy reserves in the female, energy production and production of egg proteins. We are particularly interested in how larval and adult nutrition affect this partitioning.
• We are studying how the female mosquito uses her lipid and carbohydrate reserves during a gonotrophic cycle.
• We are also studying how female mosquitoes regulate amino acid metabolism, especially in relation to how they handle the large amount of ammonia they produce during blood meal digestion and egg production.

Lipoprotein metabolism in Manduca sexta. 

Currently, we are focusing on these areas of research

•  Characterization of lipoprotein receptors. We use vertebrate tissue culture cells for expression cloning of lipoprotein receptors and stably transformed cell lines to characterize the properties of the receptors. 
• Studies on the mechanism of lipid transport. We are interested in how lipids cross membranes both during lipid absorption in the gut and in lipid transfer from lipoproteins to cells. We are expression cloning fatty acid and sterol receptors from the midgut and isolating factors that facilitate lipid transfer from cells to lipoprotein.
• A recent review highlights our current interests -" Lipid Storage and Mobilization in Insects: Current Status and Future Directions." E. L. Arrese, L. E. Canavoso, Z. E. Jouni, J. E. Pennington, K. Tsuchida, and M. A. Wells, Insect Biochem. Molec. Biol. 31, 7-17 (2001) (PDF reprint). 

Science Education using Insects

I also maintain the Manduca Project, which provides caterpillars eggs and diet to elementary school classes. See our web site http://www.manducaproject.com/ for more details.

Chapters and Reviews

Pennington, J. E. and Wells, M. A. The Midgut: Structure and Function in (Marquardt WC, Black WC, Freier J, Hagedorn H, Hemingway J, Higgs S, James AA and Kondratieff, Eds.) “Biology of Disease Vectors”, 2nd ed., Elsevier, (2004).

Zhou, G., Scaraffia, P. Y. Wells, M. A. Vector Nutrition and Energy Metabolism in (Marquardt WC, Black WC, Freier J, Hagedorn H, Hemingway J, Higgs S, James AA and Kondratieff, Eds.)  “Biology of Disease Vectors”, 2nd ed., Elsevier, 311-315 (2004).

Isoe, J, Noriega, F. G. and Wells, M. A. Genomics and Gene Expression in Vectors in (Marquardt WC, Black WC, Freier J, Hagedorn H, Hemingway J, Higgs S, James AA and Kondratieff, Eds.) “Biology of Disease Vectors”, 2nd ed., Elsevier, 551-563, 2004.

Research Publications

Proline can be utilized as an Energy Substrate during Flight of Aedes aegypti Females. P.Y. Scaraffia and M.A. Wells, J. Insect Physiol. 49, 591-601(2003).

Metabolic Fate of [14C]-Labeled Meal Protein Amino Acids in Aedes aegypti Mosquitoes, G. Zhou, M. Flowers, K. Friedrich, J. Horton, J. E. Pennington and M. A. Wells, J. Insect Physiol 50, 337-349 (2004).

Lipid Transfer Particle Mediates the Delivery of Diacylglycerol from Lipophorin to Fat Body in Larval Manduca sexta. L. E. Canavoso, H. K. Yun, Z. E. Jouni and M. A. Wells J. Lipid Res. 45, 456-465 (2004).

Characterization of the Carotenoid-Binding Protein of the Y-Gene Dominant Mutants of Bombyx mori. K. Tsuchida, Z.E. Jouni, J. Gardetto, Y. Kobayashi, H. Tabunoki, M. Azuma, H. Sugiyama, N. Takada, H. Maekawa, Y. Banno, H. Fujii, H. Iwano and M. A. Wells. J Insect Physiol. 50:363-72 (2004).

The effect of larval and adult nutrition on successful autogenous egg production by a mosquito. Telang A. and Wells M.A. J Insect Physiol. 50:677-85 (2004).

Utilization of Pre-existing Energy Stores during Blood Meal Digestion in Female Aedes aegypti Mosquitoes. G. Zhou, J. E. Pennington and M. A. Wells, Insect Biochem. Molec. Biol. 34: 919-925 (2004).

Lipid Transfer Particle Mediates the Delivery of Diacylglycerol from Lipophorin to Fat Body in Larval Manduca sexta. L. E. Canavoso, H. K. Yun, Z. E. Jouni and M. A. Wells J. Lipid Res. 45, 456-465 (2004).

Characterization of the Carotenoid-Binding Protein of the Y-Gene Dominant Mutants of Bombyx mori. K. Tsuchida, Z.E. Jouni, J. Gardetto, Y. Kobayashi, H. Tabunoki, M. Azuma, H. Sugiyama, N. Takada, H. Maekawa, Y. Banno, H. Fujii, H. Iwano and M. A. Wells. J Insect Physiol. 50:363-72 (2004).

The Basis for Colorless Hemolymph and Cocoons in the Y-gene recessive B. mori Mutants: A Defect in the Cellular Uptake of Carotenoids. K. Tsuchida, C. Katagiri, Y.Tanaka, H. Tabunoki, R. Sato, H. Maekawa, N. Takada, Y. Banno, H. Fujii, M. A. Wells, and Z. E. Jouni, J. Insect Physiol. (Journal of Insect Physiology 50:975–983 (2004).

cAMP-Dependent Protein Kinase of Manduca sexta Phosphorylates but does not Activate the Fat Body Triglyceride Lipase. R. Patel, J. L Soulages, M.A. Wells and E. L. Arrese. Insect Biochem. Molec. Biol. 34:1269–1279 (2004).

Sphingomyelinase D from venoms of Loxosceles spiders: evolutionary insights from cDNA sequences and gene structure. G.J. Binford, M.H.J. Cordes and M.A Wells. Toxicon 45:547-60 (2005).

Ammonia Metabolism in Aedes aegypti. P.Y. Scaraffia, J. Isoe, A. Murillo and M.A. Wells, Insect Biochem. Molec. Biol. 35: 491-503 (2005).

Contact Information

Mailing:
Dr. Michael A. Wells, Professor
Department of Biochemistry & Molecular Biophysics
University of Arizona
1041 E. Lowell Street
Biosciences West #516
Tucson AZ 85721-0088

Telephone: (520) 621-3847
Fax: (520) 621-9288

mawells@u.arizona.edu