Transgenic rainbow trout expressed sGnRH-antisense RNA under the control of sGnRH promoter of Atlantic salmon

A recombinant vector containing antisense DNA complementary to Atlantic sal mon (Salmo salar) sGnRH cDNA driven by specific promoter Pab derived from a corresponding sGnRH gene was introduced into rainbow trout (Oncorhynchus m ykiss) eggs. This resulted in transgenic animals that had integrated one co py of the transgene into their genome and transmitted it through the germli ne. Antisense-sGnRH mRNA (AS) was expressed mainly in the brain of transgen ic AS(+) fish. Levels of sGnRH endogenous mRNA in the brain were lower in 1 1-month-old AS(+) fish compared with nontransgenic AS(-) individuals from t he same F2 progeny, sGnRH levels significantly decreased in the pituitary o f transgenic males and females around the maturation period and in the brai n of AS(+) immature females compared with controls. No reliable statistical difference was found in the levels of FSH and LH between AS(+) and AS(-) g roups either in immature or mature fish. The majority of transgenic fish re ached maturity at the same time as did nontransgenic individuals, although the maturation of AS(+) animals seemed to be more asynchronous. For the fir st time, the influence of antisense messengers on endogenous mRNA in transg enic fish and the corresponding protein is described.