Success of Transfer and Expression of Introduced

Although conventional breeding programs in fish parallel those in chicken, unconventional techniques not available in chicken breeding, such as intersmecific hybridization (Schwartz, 1981), ploidy manipulation and gynogenesis (Thorgaard and Allen, 1987), are used in breeding of fishes. Within the last five years, another unconventional means of genetic manipulation, gene transfer, has become available to animal breeders. Techniques utilized for gene transfer in fish are quite different from those utilized in chicken. In this report, the methods and status of gene transfer in fish are reviewed, with many aspects of progress in the field exemplified with results from our own work in the Minnesota Transgenic Fish Group. Demonstration of dramatic growth in mice bearing introduced growth factor genes (Palmiter et al., 1982; _Hammer et al., 1985) created widespread interest in the possibility of producing agricultural livestock exhibiting enhanced productivity through the action of introduced genetic constructs. Because of the possible value to aquaculture, gene transfer in fish has attracted a relatively large research effort. At least 23 laboratories (Table i), nine in the U.S. and at least 14 Ln other countries, are involved in gene transfer in fish. The broad scope of the research effort has led to rapid developaent of protocols for gene transfer in fish, and the successful production of transgenic fish of at least 13 species (Table 2).