Ž . Aquaculture 173 1999 333–346 Growth performance of transgenic tilapia containing an exogenous piscine growth hormone gene M. Azizur Rahman, Norman Maclean ) DiÕision of Cell Science, School of Biological Sciences, UniÕersity of Southampton, Bassett Crescent East, Southampton, SO16 7PX, UK Abstract Three lines of transgenic tilapia were produced harbouring a novel piscine growth hormone Ž . GH gene construct containing a chinook salmon growth hormone gene spliced to ocean pout antifreeze gene regulatory sequence. One copy to multiple copies of the transgenes were integrated at a single site in the host genome. The initial transmission rate from G0 to G1 generation was found to be less than 10% in these 3 lines indicating a mosaic distribution of the transgene in the germ cells. However, transmission rates from G1 to G2 were found to follow the expected Mendelian ratio. Expression of chinook salmon GH was demonstrated in G0, G1 and G2 transgenic fish in these lines and resulted in dramatic growth enhancement. The average weight of Ž . the G1 and G2 transgenic fish was found to be 3 times P -0.001 greater than that of their nontransgenic siblings. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Transgenic fish; Growth hormone; Tilapia 1. Introduction Genetic engineering of farm animals offers great potential for improvement of selected genetic traits of agricultural significance. Several species of fish have also been used to exploit this technology for commercial purposes, and examples include at- tempted induction of freeze resistance in transgenic salmon using an antifreeze protein Ž . gene Fletcher et al., 1988 and production of growth enhanced fish using novel growth Ž . Ž . hormone GH genes Dunham et al., 1987; Brem et al., 1988; Penman et al., 1990 or Ž . Ž . an insulin-like growth factor IGF gene Chen et al., 1995 . Although several species of fish have been used to produce lines of transgenic fish, in only a few cases has germline transmission and stable long term transgene expression been satisfactorily demonstrated. ) Corresponding author. Tel: q44-1703-594403; Fax: q44-1703-594269; E-mail: nm4@soton.ac.uk 0044-8486r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. Ž . PII: S0044-8486 98 00456-6