Exotic Fish Germplasm Section of Fish Health Management Division

Lucknow, India

Exotic Fish Germplasm Section of Fish Health Management Division

Lucknow, India

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Singh A.K.,Exotic Fish Germplasm Section of Fish Health Management Division | Singh R.,Exotic Fish Germplasm Section of Fish Health Management Division
Animal Reproduction Science | Year: 2013

CYP19 aromatase is the key enzyme in vertebrate steroidogenesis, catalyzing the conversion of C19 androgens to 17β-estradiol (E2). The objective of the present study was to assess the effect of the CYP19 inhibitors (AIs) fadrozole and anastrozole on gonadal development and sex differentiation in Cyprinus carpio and investigate the possible involvement of in vivo melatonin (MLT) production during sex differentiation. The CYP19 activity in 30 day-post fertilized (30 dpf) fingerlings was inhibited by treating with fadrozole and anastrozole in doses of 100mg/kg and 200mg/kg of feed. Gonado-somatic-index (GSI) of fish decreased (P<0.005) and the changes in GSI was dose dependent. Serum testosterone (T) concentration increased (P<0.001) after AI treatments and was negatively correlated with serum E2 concentration which decreased (P<0.005). Morning serum MLT concentration decreased during the period of inhibited CYP19 activity with a positive correlation with E2 concentration. Sex-ratio in anastrazole (200mg/kg) treated fish were 98.1% males while with fadrozole treatment at the same dose resulted in a 97.1% masculinization. Histological examination of fadrozole-treated fish gonads resulted in detection of atretic follicles and intensified spermiation. The protein and lipid production was depressed in AIs-treated fish. The results suggested that fadrozole and anastrozole both effectively inhibited oogenesis and ovarian development in C. carpio accelerating testicular formation. There was a physiological correlation between CYP19 activity, E2 and MLT synthesis during gonadal development and sex differentiation. © 2012 Elsevier B.V.


Singh A.K.,Exotic Fish Germplasm Section of Fish Health Management Division
General and Comparative Endocrinology | Year: 2013

Of the techniques available to mass-produce a sterile or monosex population, the hormonal induction of sex reversal is the most widely practiced. This paper presents the synthesis of works done on sex reversal using 17α methyltestosterone (17αMT), 17β estradiol, non-steroidal aromatase inhibitors (AIs) and oestrogen receptor agonist, tamoxifen in commercially important aquaculture species mossambique tilapia Oreochromis mossambicus, Nile tilapia Oreochromis niloticus, common carp Cyprinus carpio, mahseer Tor putitora and African catfish Clarias gariepinus. Results on sex reversal for producing female T. putitora delineated that treatment to fry of T. putitora 60. days post fertilization (60. dpf) with 17β estradiol (150. mg/kg feed) fetched 69.5% female population. Further, raised temperature (23. ±. 1°C) five degrees above ambient temperature brought about 37.5% female populations which was above the control (24.4% females). Feeding tilapia O. mossambicus fry after yolk sac absorption stage (8. dpf) with 17αMT incorporated diet (35. mg/kg feed) under long photoperiod (16L:8D) for 60. days obtained 100% sex reversed males with excellent growth. Treatment with tamoxifen and letrozole (200. mg/kg feed) to fingerlings of C. carpio and O. niloticus for 60. days brought about 82.5% and 98.5% masculinization with increased level of testosterone (T). Letrozole treatments to C. gariepinus significantly (p<. 0.001) increased T level to 1197.76. ±. 18.79. pg/ml when treatment was given through feed for 60. days and 1470.5. ±. 20.76. pg/ml via intraperitoneal injection. There was significant deviation in sex ratio leading to high level of masculinization in different aquaculture species with treatments of hormones and AIs. © 2012 Elsevier Inc.


PubMed | Exotic Fish Germplasm Section of Fish Health Management Division
Type: | Journal: General and comparative endocrinology | Year: 2013

Of the techniques available to mass-produce a sterile or monosex population, the hormonal induction of sex reversal is the most widely practiced. This paper presents the synthesis of works done on sex reversal using 17 methyltestosterone (17MT), 17 estradiol, non-steroidal aromatase inhibitors (AIs) and oestrogen receptor agonist, tamoxifen in commercially important aquaculture species mossambique tilapia Oreochromis mossambicus, Nile tilapia Oreochromis niloticus, common carp Cyprinus carpio, mahseer Tor putitora and African catfish Clarias gariepinus. Results on sex reversal for producing female T. putitora delineated that treatment to fry of T. putitora 60 days post fertilization (60 dpf) with 17 estradiol (150 mg/kg feed) fetched 69.5% female population. Further, raised temperature (23 1 C) five degrees above ambient temperature brought about 37.5% female populations which was above the control (24.4% females). Feeding tilapia O. mossambicus fry after yolk sac absorption stage (8 dpf) with 17MT incorporated diet (35 mg/kg feed) under long photoperiod (16L:8D) for 60 days obtained 100% sex reversed males with excellent growth. Treatment with tamoxifen and letrozole (200mg/kg feed) to fingerlings of C. carpio and O. niloticus for 60 days brought about 82.5% and 98.5% masculinization with increased level of testosterone (T). Letrozole treatments to C. gariepinus significantly (p<0.001) increased T level to 1197.76 18.79 pg/ml when treatment was given through feed for 60 days and 1470.5 20.76 pg/ml via intraperitoneal injection. There was significant deviation in sex ratio leading to high level of masculinization in different aquaculture species with treatments of hormones and AIs.

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