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Abstract

Non-peptide hormones (like steroids) rely on Nuclear Receptors (NRs) to activate the target gene to effect hormone action. To bind with the hormone (ligand), NR has ligand binding domain (LBD). The other domain which is functionally important is the DNA binding domain (DBD), a highly conserved domain, instrumental in binding with the target gene. Evidently, NRs are ubiquitous among metazoans in both vertebrates and invertebrates. The ecdysteroids act as hormones that promote growth in several invertebrates and are known to act through the NR, theecdysteroid receptor (EcR), encoded by the ecdysteroid receptor gene (EcR). EcR expression is found to fluctuate in a stage-dependant manner related to growth. Insects became the first model organism wherein the EcR was detected and the expression was studied. Subsequently, EcR was detected in other invertebrate groups as well. Crustaceans became the other major group wherein the EcR gene expression was studied. Interestingly, Carney and Bender (2000) have demonstrated that ecdysteroid receptor is a requisite for successful vitellogenesis in Drosophila. Since then, researchers have been trying to unravel the role of EcR in insect reproduction. Investigations have also led to the identification of retinoid receptors that dimerize with the EcR to accomplish the hormone action. These results have encouraged the carcinologists to hypothesize that a comparable situation might exist in crustaceans as well. Of late, the experiments performed on Drosophila and Tribolium have shown a putative receptor (the �Met� receptor) for the terpenoid hormone (JH), analog of MF, the gonadotropic hormone in crustaceans. However, the exact mechanism of the cascade of events, beginning from the ecdysteroids, leading to vitellogenesis is yet to be understood. The present paper would discuss at length, the possibilities of these hormone receptors getting involved in growth and reproduction in invertebrates.

Biography

Anilkumar Gopinathan is a Senior Professor at the School of Biosciences and Technology, VIT University, India. He had his Postdoctoral Training in Invertebrate Molecular Endocrinology from the University of Oklahoma, USA as a DBT Overseas Associate. A two-time Grantee of Research Projects from the International Foundation for Science (IFS, Stockholm, Sweden). He is also currently the Scientific Advisor to the IFS. He had also been Visiting Scientist to the University of Gdansk (Poland), International Sakharov Environmental University (Minsk, Belarus) and the University of Oklahoma (under Indo-US DST-NSF program). He was awarded by St. Berchman’s Best Teacher, a Covetable State-Level Award. He has also chaired scientific sessions in several international conferences.

Email: ganilkumar@vit.ac.in