The results have shown a close relationship between aromatase activity and gonadal estradiol (E2) levels. However, only limited data have been available for the grouper.
The baculovirus expression system is a eukaryotic expression system that can produce posttranslational modifications of recombinant protein.
Since human beta interferon was first expressed with a baculovirus expression vector in 1983, more than 500 genes from viruses, bacteria, epiphytes, plants, invertebrates, and vertebrates have been expressed by the baculovirus expression system. Recombinant grass carp Gh is able to produce immunological and biological activities similar to the native hormone in the baulovirus-silkworm larvae system. Recombinant goldfish gonadotropin has been expressed by baculovirus, and the results suggest that the biological activities of goldfish recombinant Fsh and Lh might be used to induce gonadal development in aquaculture fishes as a substitute for pituitary extract.
The orange-spotted grouper, Epinephelus coioides, is a marine fish widely cultured in Southern China. It is a protogynous hermaphroditic fish. Females reach sexual maturity at about 5 years of age when they reach approximately 5575 cm in body length; the transition of the sex gland from female to male begins at about 7 years of age. To study the biological activities and physiological relevance of the two gonadotropins, the availability of homologous hormones was essential. As a first step in unraveling the mechanism involved in the sex change and gonadotropin function of the orange-spotted grouper, rgLh was expressed in insect cells by the baculovirus expression system, and the biological effects of the recombinant protein were determined with in vitro and in vivo approaches.