Induction of sex-reversed males using 17 α-methlytestosterone in the gold blotch grouper (Epinephelus costae)

Abstract

In this study, the effects of 17α-methyltestosterone (MT) for induction of sex reversal in protogynous hermafrodit goldblotch grouper (Epinephelus costae) was investigated. Goldblotch grouper were implanted with 5 mg (MT5) and 10 mg (MT10) 17α-methyltestosterone kg^-1 month^-1 body month weight five times with 15 days intervals. Five fish were implanted for each treatment. After week 8 post-implantation, 2 fish died in MT10 group. These two fish were dissected and MT10 oocytes were degenerated, and sperm channels of these two fish were observed. After last implantation (week 10 post-implantation), only one fish in MT5 treatment induced advanced stages of spermatogenesis. A philometrid nematode, Philometra lateolabracis (Nematoda: Philometridae) was observed in fish in MT5 treatment. It was assumed that this parasitic nematod inhibits the normal development of the gamates in sex reversed females. 

Keywords

• sex reversal,broodstock management,17α-methyltestosterone

Ziber balığında (Epinephelus costae) 17 α-metiltestosteron Kullanılarak Erkekleşmenin Öne Çekilmesi

Öz

Bu çalışmada 17α-metiltestosteron (MT)’un protogenus hermafrodit Ziber (Epinephelus costae) türünde cinsiyet dönüşümü üzerine olan etkileri araştırılmıştır. Ziber bireylerine 5 mg/kg/ay (MT5) ve 10 mg/kg/ay (MT10) 17α-metiltestosteron olacak şekilde her 15 günde bir toplam 5 kez implant yapılmıştır. Her bir uygulama için beşer balık kullanılmıştır. Sekizinci haftadaki implantın ardından MT10 grubunda bulunan 2 bireyde ölüm gerçekleşmiştir. Ölen bu balıklar disekte edilmiş, oositlerin dejenerasyona uğradığı ve sperm kanallarının belirginleştiği gözlenmiştir. Son implantın ardından (10. hafta) MT5 grubundaki bir bireyde gonadlarda fenotipik erkekleşmenin gerçekleştiği belirlenmiştir. Histolojik kesitlerde bir adet histozoik parazit olan Philometra lateolabricis’in (Nematoda: Philometridae) varlığı gözlenmiştir. Cinsiyet değişimi sağlanmaya çalışılan bireylerde  gametlerin normal gelişim gösterememesinin sebebinin bu parazitin olabileceği varsayılabilir.

Anahtar Kelimeler

• 17α-metiltestosteron,cinsiyet dönüşümü,anaç yönetimi

Kaynakça

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