ZMORA, Nilli*; TRANT, John M; CHUNG, Sook J; Center of Marine Biotechnology, Univ. of Maryland Biotechnology Institute: Characterization of a vitellogenin gene and the endocrine regulation of vitellogenesis of the blue crab, Callinectes sapidus

Vitellogenesis and vitellogenin (Vg) uptake by oocytes are crucial for ovarian development and successful reproduction in many nonmammalian species. Crustacean vitellogenesis has long been suggested to be regulated by the XO-SG endocrine system. The blue crab female reaches puberty after a terminal molt, which is usually accompanied by mating. Previous studies indicated the ovary as the site of vitellogenesis^1,2. However, by isolating and characterizing cDNA of the blue crab Vg gene we have found that the hepatopancreas, not the ovary, is responsible for vitellogenesis. This was confirmed by Northern blot analysis and immunohistochemistry. Using 5�-3�RACE, the full length of 7.8 Kb Vg cDNA was amplified from the hepatopancreas. Callinectes Vg gene, like those from other crustaceans, possesses typical motifs such as cleavage and phosphorylation sites and shares 80% of sequence homology with Vg cDNA of Charybdis feriatus³. In order to understand the regulation of vitellogenesis of the blue crab, we monitored hemolymph Vg levels and gene expression in the hepatopancreas during ovarian development using a competitive ELISA and QRT-PCR, respectively. Hemolymph Vg and ovarian morphology indicate that the female undergoes a short spontaneous vitellogenesis, which is independent of mating. In vitro incubation of hepatopancreas explants with CHH and MIH neuropeptides, farnesoic acid and ecdysteroids showed that the XO-SG endocrine system may play an important regulatory role in vitellogenesis of the blue crab. Further investigation of the endocrine regulatory mechanism of female blue crab reproduction is in progress. 1. Lee CY & Watson D. J Exp Zool. 1995. 2. Lee RF & WalkerA. J Exp Zool. 1995. 3. Mak et al. Ann N Y Acad Sci. 2005.