Efficacy of 17 α-methyl testosterone and letrozole on sex reversal of protogynous grouper,Epinephelus tauvina(Forskal, 1775) and spawning performance of sex-reversed males

Abstract

This study aimed to test the efficacy of 17 amethyl testosterone (17 a-MT) alone and in combination with letrozole, an aromatase inhibitor, for the induction of sex reversal in protogynous greasy grouper, Epinephelus tauvina. Further, the long-lasting effects of these treatments and spawning performance of sex-reversed males were also investigated. Greasy grouper with oocytes in the perinucleolus stage were implanted with 5 mg 17 a-MT kg À1 body weight (T 1 ), 5 mg 17 a-MT and 0.2 mg letrozole kg À1 body weight (T 2 ) and 5 mg 17 a-MT with 0.4 mg letrozole kg À1 body weight (T 3 ) and no androgens/enzyme inhibitor implanted (C). The 17 a-MT alone and in combination of letrozole-induced sex reversal in greasy grouper, whereas untreated control fish (C) showed normal ovarian development. However, T 2 and T 3 group showed 100% sex reversal and completion of spermatogenesis up to functional male phase in 2 and 3 months, respectively, whereas T 1 group resulted in only 66.67% functional male with motile spermatozoa after 4 months. Sex-reversed males successfully fertilized the eggs during induced spawning. There were significant differences on fertilization and hatching rates between T 2 group (79.00 AE 4.36%; 77.67 AE 2.87%, respectively) and T 1 group (57.67 AE 3.17%; 63.87 AE 2.91%, respectively). The result suggested that 17 a-MT (5.0 mg kg À1 BW) in combination with letrozole (0.2 mg kg À1 BW) has the potential to produce 100% sex-reversed male in short period in greasy grouper, which might greatly help in seed production of greasy grouper.

Conditioning, maturation and year-round natural spawning of orange-spotted grouper,Epinephelus coioides(Hamilton, 1822), in recirculating aquaculture system

“…Similarly, Ranjan et al. () had reported that female fish were converted to male after 2 months of implantation of letrozole and 17 α‐MT in greasy grouper. It is understood that treatment with 17 α‐MT probably increases the androgen level in the blood; however, 17 α‐MT can be converted to oestrogen by P450 aromatase, which may also increase the oestrogen level (Kwon, McAndrew & Penman, ).…”

“…Thus, after 15 days of stocking, a total of 15 fish were randomly selected for sex reversal from female to male and were implanted with a combination of 17 α methyl testosterone (MT) and letrozole at the rate of 5 mg and 0.2 mg/kg body weight respectively. The dosage of hormone and enzyme selected and the procedure for pellet preparation and implantation were based on our earlier work (Ranjan et al., ). The remaining 15 fish were left without any implantation for development of female brooders.…”

Effects of 17α‐methyltestosterone on the growth performance, development, and reproduction of gynogenetic topmouth culter ( Culter alburnus Basilewsky)

“…and Nile tilapia (Kwon, McAndrew, & Penman, 2002;Ranjan et al, 2015). These studies indicated that increasing E2 might be due to aromatization of 17α-MT to estrogen by P450 aromatase.…”

“…Changes in growth hormone (GH) and tetraiodothyronine (T4) can reflect the growth status and testosterone (T) while estradiol can reflect the gonadal development status of fish (Power et al, 2001;Ranjan et al, 2015). Hence, comprehensive understanding of oxidation-reduction-related enzymes and growth and reproduction-related hormones is essential for evaluating the effects of exogenous 17α-MT on topmouth culter.…”

Artificial sex reversal of white grouper ( Epinephelus aeneus ) utilizing aromatase inhibitor (Fadrozole)

“…The white grouper ( Epinephelus aeneus ) in the Mediterranean Sea region is not an exception and are threatened by an increasing consumer demand. In Southeast Asia, grouper culture has been implemented and is taking advantage of the species of grouper that have rapid growth, disease resistant and efficient feed conversion (Ranjan et al, ). Decreasing amounts of wild fish and bans on the fishing of groupers in the Mediterranean region prompted studies targeting culture of native grouper species, such as the white grouper.…”