PRODUCTION OF A BIOLOGICALLY-ACTIVE NOVEL GOLDFISH GROWTH-HORMONE IN ESCHERICHIA-COLI

Goldfish pituitary contains two types of growth hormones. One with fiv e cysteine residues (type-I) similar to other Cyprinid GHs, and the ot her with four Cys residues (type-II) similar to those of other fish an d tertapod species. Recombinant goldfish type II GH (gfGH-II) was prod uced in Escherichia coli using the pRSETB expression vector. The gfGH- II was produced fused to a leader sequence, which sequestered into inc lusion bodies after expression. The inclusion bodies were solubilized using sodium hydroxide and the fusion protein purified by chelating af finity chromatography. Subsequently, gfGH-II was cleaved and analyzed by Western blotting, using a specific antiserum. For comparison we als o produced recombinant common carp GH (cGH) which has 95% similarity t o gfGH-II, and tested their growth promoting activity in goldfish. Bot h forms of GH significantly increased the growth rate of goldfish (P < 0.05), although cGH was found to have a somewhat higher potency than gfGH-II. (C) 1998 Elsevier Science Inc. All rights reserved.