关键词:
Oocyte maturation and hydration
Free amino acid
Ions
Oocyte quality
Orange-spotted grouper
摘要:
In aquaculture, oocyte maturation, ovulation and spawning are important for successful breeding and seed production. Most marine teleost fish can be induced to spawn regularly using intramuscular injections of human chorionic gonadotropin (HCG). In this study, an intra-ovarian injection method was developed in orange-spotted grouper to deal with the broodstocks unresponsive to HCG. Successful oocyte maturation and ovulation in the unilateral injected ovary was induced within 35 h of treatment. An in vitro method was then established to induce HCG-primed oocyte maturation. HCG or maturation-inducing hormones (MIHs) induced the maturation of oocytes with a diameter between 490 and 560 mu m. Biochemical, physiological and molecular changes during oocyte maturation and hydration were also characterized. The concentration of free amino acids except the cysteine increased during oocyte maturation, whereas Na+ decreased steadily and K+ increased. The expression of genes encoding cathepsin B, D, L, and the subunits of Na+ , K+-ATPase were upregulated during hydration. Specific inhibitors for cathepsin and Na+ , K+ -ATPase were used to further confirm their crucial roles in oocyte hydration both in vivo and in vitro. These results provide valuable data for inducing oocyte maturation and evaluating oocyte quality in marine teleost fish.