EXPRESSION AND ALTERNATIVE PROCESSING OF A CHICKEN GENE ENCODING BOTHGROWTH HORMONE-RELEASING HORMONE AND PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE

The chicken growth hormone-releasing hormone (GRF) gene was isolated, sequenced, and characterized, In addition, three different mRNAs were isolated from juvenile and adult brain, The first cDNA encoded for a G RF(1-46), the second cDNA encoded for a GRF(1-43) due to a sliding int ron boundary, and the third skipped exon four and encoded only GRF(33- 46). We also determined that juvenile chicken mRNA encoding GRF is exp ressed in the brain and gonads, but not in the pituitary, heart, liver , kidney, crop, small intestine, large intestine, eye, and muscle, Thi s gene is also interesting in terms of evolution because another neuro peptide, pituitary adenylate cyclase-activating polypeptide (PACAP), i s encoded within the same gene (grf/pacap) in chicken, but on a separa te gene (pacap) in mammals, We showed previously that these two neurop eptides were encoded in the same cDNA in fish, but the present evidenc e in chicken suggests a gene duplication in stem mammals.