S Sridhara, Ph.D.
| Associate Professor | s.sridhara@ttuhsc.edu |
Biography
Ph.D. from the Indian Institute of Science, Bangalore India. Post-doctoral studies at UCLA Medical School and Harvard Medical School. Having spent about a year each at the University of Lyon France and NIH as a visiting scientist, I went to Northwestern University, Evanston Illinois as an Established Investigator of the American Heart Association. It is there that I developed my continuing interest in understanding the biochemical and molecular biological basis of hormonal regulation of insect development and metamorphosis using silkmoths as the experimental model.
Research Interests
Two hormones - Ecdysone, a steroid hormone and Juvenile Hormone, a sesquiterpenoid - regulate the multitude of biochemical activities involved in growth, metamorphosis, homeostasis, and even reproduction in all insects. The fact that all the millions of species in the class Arthropoda, with an evolutionary history of ' 600 million years, utilize these hormones to regulate their physiological functions, accentuates the importance of understanding the structure and function of the receptors for these hormones: Hence current research in the laboratory is focused on these two hormone receptors: (1) Functional Analysis of the Ecdysone Receptor: Studies on E/EcR regulation of gene activity will define how steroid dependent hierarchy of transcription factor expression, and the consequent protein-protein interactions, combine to signal either tissue development or differentiation. The goals of our studies are to answer the following questions: (1). Does EcR use different response elements for gene regulation at different stages of development? (2). How does EcR regulate gene activity in the absence of the ligand? and (3). What other proteins interact with EcR to account for differential gene activity that occurs in a hormonal-, developmental-, and tissue-, specific manner?, (2) Molecular Characterization of Juvenile Hormone Receptor: Definitive understanding of the mechanism of action of the Juvenile Hormone requires the isolation and characterization of the receptor for this hormone (JHR) that has not yet been achieved. The main goal of our studies is to take advantage of the exogenous Juvenile Hormone’s ability to promote a second pupal development in silkmoths to characterize the JHR. Currently we are extending our studies with a new affinity agonist that has been developed for purification, expression screening, and phage display selection in appropriate combinations to successfully achieve the stated goal.
Recent Publications
- Sridhara, S, Bhaskaran, G., Dahm, K. H. (2004). Endocrine Glands and Hormones. In Handbuch der Zoologie, Vol 4. (N. P. Kristensen, ed), Walter De Gruyter Berlin. pp 389-425.
- Sridhara, S. and Mattes, C.E. 20-Hydroxy ecdysone regulates RNA polymerase I activity by stimulation of synthesis and phosphorylation. Molec. Cell. Endo. 111:39-99, 1995.
- Sridhara, S. RNA polymerases and transcriptional activity of the fat body during the final instar of the tobaco hornworm Manduca sexta. Arch. Insect Biochem. Physiol. 30:115-132, 1995.
- Moine, A. and Sridhara, S. Molecular characterization of four cuticle protein genes of the silkmoth Antheraea polyphemus specific for the adult stage. Insect Biochem. Mol. Biol. 24:919-928, 1994.
- Mattes, C.E., Sridhara, S. Immunoassay for the quantitation of DNA dependent RNA polymerase I: A procedure applicable to other proteins present in minute amounts and/or isoforms. Immunology Lett. 36: 209-214, 1993.
- Sridhara, S. Evidence for the existence of different gene sets specifying pupal and adult wings in the silkmoth Antheraea polyphemus. Insect Biochemistry 15, 333-339, 1985.
- Gowda, S., Sridhara, S. Monoclonal antibodies to RNA polymerase I of the silk glands of the silkworm Bombyx mori. J. Biol. Chem. 258, 14532-14538, 1983.