C. GHOSH, A.K. RAY, S. BHATTACHARYA AND SHELLEY BHATTACHARYA
Abstract
Hypothalamic gonadotropin releasing hormone (GnRH) fraction, Acetone fraction II (AcF-II) was tested for inducing ovulation in an air-breathing fish, Anabas testudineus. The min'imal effective standard dosage of 37.5 IA e/ 100 g body weight was administered to the female fish in two instalments. An additional dose of 25l_a.,Y/100 g body weight of eGnRH to the female fish was required for complete maturation and ovulation. The male fish on the other hand, received single injection of c-GnRH (25 j.i.g1100 g body weight) at the time of second injection to the female. The experiment was carried out at the ambient temperature of 28°C and pH 7.4. The response of the female fish to metacid-50, an organophosophate pesticide, was also investigated in a similar condition with the same dosage of cGnR I I fraction (AcF-11). It was observed that the exposure of the fish to .safe concentration (0.106 ppb) of metacid50 for seven days resulted in complete failure in inducing maturation and ovulation, however with a similar dosage of cGnRH and which successful ovulation occurred in the control fish. This indicates that apparent safe concentration of metacid-50 in ambient water is sufficiently effective in producing reproductive inefficiency.