Now showing items 1-6 of 6

    • Article

      Effect of season on oocyte development and serum steroid hormones in LHRHa and pimozide-injected catfish Clarias macrocephalus (Günther) 

      JD Tan-Fermin, CL Marte, H Ueda, S Adachi & K Yamauchi - Fisheries Science, 1999 - Japanese Society of Fisheries Science
      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.
    • Article

      The in vitro effects of cyclic nucleotides, cyanoketone, and cycloheximide on the production of estradiol-17β by vitellogenic ovarian follicles of goldfish (Carassius auratus) 

      JD Tan, S Adachi & Y Nagahama - General and Comparative Endocrinology, 1986 - Academic Press
      The effects of human chorionic gonadotropin (HCG), forskolin, cyclic nucleotides, the phosphodiesterase inhibitors IBMX and theophylline, cyanoketone, and cycloheximide on the production of estradiol-17β by isolated ovarian follicles of vitellogenic goldfish (Carassius auratus) were examined using 18-hr incubations. HCG and all test agents which are known to increase intracellular concentrations of cAMP significantly stimulated the production of estradiol-17β. However, dibutyryl cGMP was unable to stimulate estradiol-17β production at any concentration used (1–10 mM). Cyanoketone at a concentration of 1 μg/ml completely blocked forskolin-induced estradiol-17β production. Even in the presence of cyanoketone, however, forskolin stimulated conversion of exogenous testosterone to estradiol-17β in a dose-dependent manner, suggesting the involvement of an adenylate-cyclase system in the induction of aromatase activation by vitellogenic follicles of goldfish. Cycloheximide also completely abolished HCG-induced estradiol-17β production when this inhibitor was added within the first 1 hr after the addition of HCG. These results provide evidence that the stimulation of estradiol-17β by goldfish vitellogenic follicles in response to HCG is dependent upon the synthesis of new protein.
    • Article

      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 Science
      Ovarian 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.
    • Article

      Seminal plasma composition, sperm motility, and milt dilution in the Asian catfish Clarias macrocephalus (Gunther) 

      JD Tan-Fermin, T Miura, S Adachi & K Yamauchi - Aquaculture, 1999 - Elsevier
      Ionic composition of the seminal plasma and factors that initiate sperm motility in the freshwater Asian catfish Clarias macrocephalus, were examined to develop an artificial seminal plasma (ASP) that can be used to dilute milt. The optimum ratio of milt:ASP that can reversibly activate the sperm and milt–ASP:ovulated eggs that will result in high fertilization rates were further determined to minimize the number of males to be sacrificed during artificial insemination. Seminal plasma of C. macrocephalus contained 17.8±0.1 mM/l potassium, 164.4±0.6 mM/l sodium, 8.4±0.0 mM/l calcium and 1.6±0.0 mM/l magnesium, and had an osmolality of 269.0±6.4 mOsm/kg, and pH of 7.8±0.2. Sperm motility was highest and longest in all electrolyte (NaCl, CaCl2, KCl) and non-electrolyte (mannitol) solutions of 200 mOsm/kg. Catfish sperm were motile in all isotonic NaCl–KCl solutions, and were reversibly activated in the ASP (143 mM NaCl, 30 mM KCl, 8 mM CaCl2, 2 mM MgCl2, 10 mM HEPES) solutions of pH 6.4–9.4. Altogether, these results suggest that sperm motility in C. macrocephalus was mainly initiated by a decrease in osmotic pressure, rather than ions and pH. High fertilization rates (89–94%) were observed when 10 μl milt, diluted with 1000 μl ASP, was activated with 5 ml of 0.6% NaCl (198.24 mOsm/kg) to fertilize 5 or 10 g of ovulated eggs. Results obtained from the present study provide information on sperm physiology that will lead to more efficient gamete management, and hopefully, an increase in the yield of catfish fry in the hatchery.
    • Conference paper

      Serum steroid hormones, reproductive and larval performance of the Asian catfish Clarias macrocephalus (Gunther) during the off- and peak reproductive seasons 

      JD Tan-Fermin, CL Marte, S Adachi & K Yamauchi - In JYL Yu (Ed.), Recent Advances in Comparative Endocrinology. Proceedings of the Fourth Congress of the Asia and Oceana Society for Comparative Endocrinology, May 14-18, 2000, Academia Sinica, Taipei, Taiwan, R.O.C, 2001 - Institute of Zoology, Academia Sinica, Taipei, Taiwan, R.O.C.
      Serum samples were taken from gravid female catfish 0 to 24 h after injection of luteinizing hormone releasing hormone analogue (LHRHa) and pimozide (PIM) to monitor the serum steroid hormone levels during the off seasons (February) and the peak of the natural breeding period (August). A parallel study was also conducted to compare egg production, fertilization, hachuring and larval rates upon yolk resorption from spawn’s of hormone-treated fish. Serum E2 levels were significantly different only with varying times after injection (PI); a marked increase occurred at 13 h, but the elevation was higher in fish induced to ovulate during the peak (16.8 ng/ml) than off season(7.7ng/ml). Hormone-treated fish showed higher serum testosterone (T) levels during the peak season (17-23 ng/ml) than those injected during the off season (10-20 ng/ml) at 4-12 h PI. Serum 17¤, 20ß-dihydroxy-4-pregnene-3-one (DHP) levels og hormone-treated fish during the off season were only about half the level (0.29 and 0.52ng/ml) of those treated with the same hormones during the peak season (0.54 and 0.9 ng/ml) at 8 and 12 h PI, respectively. Initial eggs size was larger in fish induced to spawn in August (1.54 mm) than in fish induced in February (1.49 mm). All fish ovulated when induced to spawn during the peak of the natural breeding period, but ovulation rate was only 60% when were injected during the off season. Egg production, fertilization, hatchery and survival rates were similarly much higher when gravid females were induced to spawn in August (88 eggs/g body weight, 97%, 73%, and 95%, respectively) than those spawned in February (20 eggs/g BW,36%, 20%, and 47%, respectively). Results indicate that more eggs and of better quality, higher levels of T and DHP were produced during the peak season.
    • Article

      Testicular histology and serum steroid hormone profiles in hatchery-bred catfish Clarias macrocephalus (Gunther) during an annual reproductive cycle 

      JD Tan-Fermin, T Miura, H Ueda, S Adachi & K Yamauchi - Fisheries Science, 1997 - Japanese Society of Fisheries Science
      Testicular development, gonadosomatic index (GSI), and related steroid hormones (testosterone or T, 11-ketotestosterone or 11-KT, 17α, 20β-dihydroxy-4-pregnen-3-one or DHP) in serum were monitored during an annual reproductive cycle in tank-reared, hatchery-bred male catfish Clarias macrocephalus to established the season optimum for its artificial propagation. GSI values were highest in June (0.80%), and lowest in December, February, April (0.36%). At most times of the year, lobules in the testis and seminal vesicles were mostly lined with spermatogonia B (SGb) and spermatocytes (SC) and few spermatogonia A (SGa); spermatids (SD) and spermatozoa (SZ) were the least and most abundant of the spermatogenic cells, respectively. In January however, almost equal counts of SGa, SGb and SC were observed, as well as a significant increase in the percentage of SD and corresponding decrease in SZ. Serum 11-KT fluctuated at high levels, with the lowest level in January (159.42 ng/ml), and peak in September (434.72 ng / ml). Serum T levels ranged from 15-25 ng/ml, and were not markedly different throughout the annual cycle. Serum DHP levels were extremely low in January-May, and reached maximum levels in July (0.18 ng/ ml). Seasonal changes in the percentage of spermatogenic cells, GSI and serum steroid hormone profiles showed that captive, hatchery-bred male C. macrocephalus have a continuous reproductive cycle. Although milt release was not observed, males can readily be used as source of milt for artificial propagation at any time of the annual cycle, except in January.