Effect of melatonin and pinealectomy on gonadal activity during prespawning period of catfish (Heteropneustes fossilis)

Aim: The effects of intraperitoneal administration of melatonin dose (25, 50, 100, 200 and 400 mg per fish) on gonadal activities were evaluated during the prespawning period of catfish, Heteropneustes fossilis for 60 days. Methodology: In this experiment, fourteen aquariums were used because the experiment was performed in replicate and fifteen fishes were suspended in each glass aquarium. One group of male and female catfishes were considered as control group and the catfishes in the second group were pinealectomized whereas the remaining five treatments were administered with low (25, 50 mg per fish) and high (100, 200, 400 mg per fish) doses of melatonin. Results: During prespawning period of reproductive cycle, the gonado-somatic index of ovary of pinealectomized and melatonin treated fish decreased as compared to the control group. The number of yolky oocytes significantly decreased in the melatonin treated group as compared to the control group. After 60 days of pinealectomy, it showed inhibitory effects on the ovarian activity. The GSI of testes of pinealectomized fish decreased as compared to the control group. The number of spermatozoa cells increased with the increase in the melatonin dose as compared to control group. The GSI of testes was found maximum in the melatonin treated group as compared to the control group. Interpretation: This study supports the concept that melatonin hormone administration helps in maturation of testes and increases the number of spermatozoa. This was just contrary to the results obtained in female catfish where melatonin treatment showed inhibitory effects on the ovarian activity during prespawning period.

Restriction fragment length polymorphisms of the human N-myc gene in normal healthy individuals and oral cancer patients in India.

Southern blot hybridization with N-myc oncogene probes coding for different regions of the N-myc gene demonstrated three polymorphic restriction sites in the Indian population. The SphI and PvuII polymorphic pattern due to the SphI polymorphic site in the second intron and the PvuII polymorphic site in the 3'-region of the human N-myc oncogene respectively, was similar to that reported in the Japanese population. The allelic frequency distribution for SphI polymorphism did not differ significantly for the S1 and S2 alleles representing presence (allele S1) or absence (allele S2) of a SphI site. However, the allelic frequency distribution was distorted in the case of PvuII polymorphism, as the frequency of P1 allele (0.7) indicating presence of PvuII site, was higher than the P2 allele (0.3) indicating absence of PvuII site, in the Indian population. An additional polymorphic HindIII site localised in the second intron of the N-myc gene was also observed in both the Indian oral cancer patients and the normal healthy individuals, indicating that this RFLP was not tumor associated and may perhaps represent N-myc alteration in the Indian population.