Occurrence of vertebrate steroids, estradiol 17 beta and progesterone in the reproducing females of the mud crab Scylla serrata

In crustaceans, vitellogenesis is known to be controlled by eyestalk neurop eptides, biogenic amines, ecdysteroids and a juvenile hormone-like compound , methyl farnesoate. In recent years, the occurrence of vertebrate steroid hormones, estradiol 17 beta (E-2) and progesterone (PG) has also been repor ted in a few decapods, although their precise role in female reproduction i s yet to be determined. The levels of E-2 and PG in the ovary, hepatopancre as and the hemolymph of the red mud crab, Scylla serrata were analyzed in d ifferent vitellogenic stages in order to establish a correlation between ho rmone profile and stages of vitellogenesis. It was observed that the levels of both the steroids increased steeply in the tissues at the onset of vite llogenesis (vitellogenic stage I). Maximum levels of estradiol were present in the hepatopancreas whereas the highest concentration of progesterone wa s seen in the ovary, suggesting dichotomous roles for these hormones in vit ellogenesis. Furthermore, levels of these hormones were estimated in differ ent embryonic stages of the eggs of the sand crab Emerita asiatica and mud crab S. serrata. Their levels fluctuated, following a definite pattern in t he different stages, suggesting a possible functional role as morphogenetic hormones. This study, in addition, also reports the presence of E-2 and PG on lipovitellin purified from ovary and eggs as well as vitellogenin purif ied from the hemolymph implicating a role for these lipoproteins as steroid carriers. (C) 2001 Elsevier Science Inc. All rights reserved.