Effect of season on oocyte development and serum steroid hormones in LHRHa and pimozide-injected catfish Clarias macrocephalus (Günther)
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Oocyte and blood samples were taken from gravid female catfish Clarias macrocephalus at 4-h intervals to monitor the stage of oocyte development and serum steroid hormone profiles after injection of luteinizing hormone-releasing hormone analogue (LHRHa) and pimozide (PIM) during the off-season (February) and the peak of the natural breeding period (August). Results showed that the onset of final oocyte maturation (12h) and ovulation (16h), and levels of serum estradiol-17β (E2) did not vary with season in LHRHa+PIM-injected fish. In February, ovulated eggs were stripped from three and two hormone-treated fish at 16h and 20h post-injection, respectively. In August, ovulation was observed in all hormone-treated females (n=5) at 16h post-injection but stripping of the eggs was possible only 4h thereafter. Serum E2 levels were significantly different only with varying time post-injection; a marked increase occurred at 12h, but the elevation was higher in fish induced to ovulate during the peak (16.8ng/ml) than off-season (7.7ng/ml). Hormone-treated fish showed higher serum testosterone (T) levels during the peak season (17-23ng/ml) than those injected during the off-season (10-20ng/ml) at 4-12h post-injection. Serum 17α, 20β-dihydroxy-4-pregnene-3-one (DHP) levels of hormone-treated fish during the off-season were only about half the level (0.29 and 0.52 ng/ml) of those treated with the same hormones during the peak season (0.54 and 0.9ng/ml) at 8 and 12h postinjection, respectively. Development of oocytes and serum steroid hormone profiles after LHRHa+PIM-induced ovulation provide basic understanding of the processes that mediate final oocyte maturation and ovulation in captive C. macrocephalus.
CitationTan-Fermin, J. D., Marte, C. L., Ueda, H., Adachi, S., & Yamauchi, K. (1999). Effect of season on oocyte development and serum steroid hormones in LHRHa and pimozide-injected catfish Clarias macrocephalus (Günther).
PublisherJapanese Society of Fisheries Science
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Ovarian development and serum steroid hormone profiles in hatchery-bred female catfish Clarias macrocephalus (Gunther) during an annual reproductive cycle JD Tan-Fermin, S Ijiri, H Ueda, S Adachi & K Yamauchi -
Fisheries Science, 1997 - Japanese Society of Fisheries ScienceOvarian development e.g. gonadosomatic index, oocyte diameter, fecundity, histology, and related steroid hormones e.g. testosterone (T), estradiol-17 β (E2), 17α, 20 β-dihydroxy-4-pregnen-3-one (DHP), were examined in captive female catfish Clarias macrocephalus during an annual cycle to establish the optimum season for its artificial propagation. Results showed that captive C. macrocephalus had a group-synchronous pattern of ovarian development, as indicated by the presence of oocytes at all stages of development throughout the annual cycle. Mean gonadosomatic index (GSI; 11-13%), oocyte diameter (1.54-1.56 mm), fecundity (80-110 eggs/g body weight), and serum T levels (36-37 ng/mL) were lowest in January-April, suggesting that it is not the optimum season to induce C. macrocephalus to spawn during these months. Serum E2 levels were lowest in January (7 ng/mL), and highest in December (20 ng /mL). Serum DHP levels were below detectable limits (<0.02 ng/mL) throughout the year, supporting the observation that final maturation and ovulation do not occur in this species under captive conditions. Changes in various reproductive parameters and steroid hormone levels indicate that January-March, April-June, July-September and October-December correspond to the refractory, preparatory, spawning and post-spawning periods, respectively, of the annual cycle. The results of the present investigation can be used as a guide for the controlled breeding and commercial aquaculture of C. mucrocephalus in the Philippines.
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