HORMONAL REGULATIONS OF OVARIAN DEVELOPMENT AND VITELLOGENESIS IN CHINESE MITTEN CRAB ERIOCHEIR SINENSIS FED ON TWO DIFFERENT DIETS
两组不同饲料对中华绒螯蟹(Eriocheir sinensis) 卵巢发育及卵黄发生的激素调控

crustaceans, ovarian development and vitellogenesis are known to be regulated by circulating hormones. This study examined the hormonal regulations of ovarian development and vitellogenesis in Chinese mitten crab Eriocheir sinensis fed on two different diets (group A, lipid nutrition balance; group B, lipid nutrition unbalance). The concentrations of progesterone (PG) and estradiol (E2) in the hepatopancreas, ovary, and hemolymph of E. sinensis were measured at different vitellogenic stages by radioimmunoassay. Methyl farnesoate (MF), biosynthesized and secreted by mandibular organ (MO), were analyzed by radiochemical method. The main results were as follows: 1) Occurrence of PG and E2 in the hepatopancreas, ovary and hemolymph, and PG might be the precursor of E2; 2) MF biosynthesis rates of precocious crabs were markedly higher than those of normal juvenile crabs, and large amounts of MF biosynthesized and secreted by MO were the endocrine basis for precocity; 3) MF biosynthesis rates of group B (diets containing pork lard ) were higher than those of group A (diets containing fish oil and soy lecithin), and conversion rates of PG to E2 of group B were also higher than those of group B; 4) PG and E2 possibly bound to Exogenous vitellogenin (Vg) at their lipid binding sites, and were then transported via haemolymph to follicle cells via receptor-mediated endocytosis, and finally integrated with endogenous Vg of oocytes, resulting in their incorporation into the yolk; 5) PUFA such as EPA and DHA might inhibit the production of steroid hormone. Results of this study indicated that MF might act as a gonadotropin which stimulated PG synthesis and E2 conversion, and these three hormones together induced ovarian development and vitellogenesis.