EXPRESSION OF GROWTH-HORMONE GENES IN ATLANTIC SALMON

Atlantic salmon (Salmo salar) possess two genes encoding GH. We have i nvestigated the expression of these two genes in the salmon pituitary. The transcriptional start site was localized 64 nucleotides upstream of the first methionyl codon using primer extension and 5' specific po lymerase chain reaction (PCR) assays. Northern analysis revealed a maj or Atlantic salmon GPI (salGH) transcript band of approximately 1400 n ucleotides. As coexpression of the salGH genes is not discernible by t ranscript length, other techniques were used to assess gene activity; RNase protection analysis revealed GH transcript heterogeneity, while reverse transcription-PCR assays detected transcripts from both genes at approximately equivalent amounts. The encoded salGH protein, genera ted in in vitro and by Escherichia coli, shares electrophoretic and im munoreactive identity with native pituitary salGH.