Masculinization of genetic female nile tilapia (Oreochromis niloticus) by dietary administration of an aromatase inhibitor during sexual differentiation.
A series of experiments was carried out in which genetically female Nile tilapia (Oreochromis niloticus) fry were treated with Fadrozole, a nonsteroidal aromatase inhibitor (AI), in the diet during the period of sexual differentiation. Batches of tilapia fry treated with AI during the first 30 days following yolk-sac resorption (7-37 days post hatch, dph) showed a dose-dependent increase in the percentage of males from 0 to 200 mg. kg(-1). The percentage of males remained approximately constant (92.5-96.0%) from 200 to 500 mg. kg(-1). Any continuous 2- or 3-week treatment with 500 mg. kg(-1) AI in this 4-week period successfully masculinized the majority of the treated fish (>80%). Treatments of 1 week duration revealed that the most sensitive time to AI lies in the first week (between 7 and 14 dph). Progeny testing of males from AI-treated groups gave results indicating that these were XX males, as expected. These experiments strongly implicate aromatase activity as a key factor in sexual differentiation in the Nile tilapia.
Kwon
J Y
JY
The Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, Scotland, United Kingdom.
Haghpanah
V
V
Kogson-Hurtado
L M
LM
McAndrew
B J
BJ
Penman
D J
DJ
D000818:Animals; D047072:Aromatase Inhibitors; D004032:Diet; D012734:Disorders of Sex Development; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D017316:Fadrozole / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D008297:Male; D012727:Sex Characteristics; D012733:Sex Differentiation / Q000187:drug effects*; D012744:Sex Ratio; D017210:Tilapia / Q000502:physiology*
D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors; D017316:Fadrozole