author(s)
S Selvaraj, B Ahilan, A Yamaguchi and M Matsuyama

abstract
Gonadotropin-releasing hormone (GnRH) is the major neuroendocrine hormone regulating reproduction in vertebrates, including finfish. In recent years, presence of GnRH and their function in reproduction has been confirmed in shellfish, crustaceans and molluscs. Interestingly, shellfish GnRH do not cluster within finfish GnRH, suggesting diversity in gnrh genes and their evolution in animal kingdom. GnRH analogues have been synthesized chemically and successfully used in induced reproduction of finfish. Studies on GnRH potency in induced maturation and spawning of shellfish are limited. The present paper report the recent information of shellfish GnRH cDNAs that have been successfully isolated in number of molluscan species, and would help in the farming of shellfish under controlled conditions. Also, the paper highlights the scintometric mapping of GnRH research in fish, suggesting rapid accumulation of information on fish GnRH and their importance in fish reproductive biology and endocrinology.