A full length cDNA encoding yellow tail (Seriola quinqueradiata) growth hormone has been cloned into an expression vector, pUK319, which contains a Rhodobacter specific replicon. The resulting plasmid, pKGH319 was introduced by transformation into the marine photosynthetic bacterium Rhodobacter sp. strain NKPB0021. The plasmid was maintained as an autonomous replicon and showed good stability in the absence of antibiotics. Fish growth hormone was purified by HPLC from yellow tail pituitary glands and used to raise polyclonal antibodies for immuno blot analysis of Rhodobacter recombinants. Recombinant growth hormone was immunoreactive to mouse antiserum against natural yellow tail hormone. Our results suggest that the fish growth hormone gene was expressed under the lac promoter of Escherichia coli to levels suitable for the use of recombinant photosynthetic bacteria as a marine fish feed supplement.
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