Promotion of Rapid Growth of Rainbow Trout (Salmo gairdneri) by a Recombinant Fish Growth Hormone

The rainbow trout (Salmo gairdneri) growth hormone (GH) cDNA clone isolated previously programs the synthesis in Escherichia coli of a chimeric GH polypeptide that differs from the mature form of the natural hormone by an additional 11 amino acid residues at the NH 2 -terminus. Treatment of yearling rainbow trout with an enriched preparation of this recombinant GH resulted in enhancement of growth. Specific growth rates, weight increase, and length increase of GH-treated fish were markedly higher than those of the mock-treated or untreated fish. In addition, the chemical composition and ultrastructure of muscle tissue of GH-treated fish were not significantly different from that of control fish. These results suggest that the recombinant GH possesses growth-promoting activity and that GH-treatment results in not only accelerated but also normal growth of fish.