Title: NUCLEOTIDE SEQUENCE OF THE TURKEY PROLACTIN GENE AND ITS REGULATORY REGION
Kurima Kiyoto, - VA POLYTECHNIC INSTITUTE
El Halawani Moha, - UNIVESITY OF MINNESOTA
Wong Eric A, - VA POLYTECHNIC INSTITUTE
Submitted to: Poultry Science Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1994
Publication Date: N/A
Interpretive Summary: Incubation behavior is the birds natural tendancy to cease laying and incubate a nest of eggs. This behavior is a substantial cost to the producer of turkey hatching eggs. Prolactin is a pituitary hormone that plays an important role in ending egg production and inducing incubation behavior. The induction of incubation behavior is associated with a 50-fold increase in serum prolactin levels, and a 100-fold increase in pituitary prolactin messenger RNA (mRNA) levels. Thus, increased transcription of the prolactin gene appears to be an important step in ending egg laying and initiating incubation. This work determined the nucleotide sequence of the turkey prolactin gene, and determined possible sites where specific regulatory molecules may bind to the gene initiate prolactin synthesis is pituitary cells, or to increase or decrease prolactin mRNA synthesis. The results showed that estrogen, a major regulator of prolactin synthesis in mammals, does not appear to have a binding site on the turkey prolactin gene, but that Pit-1 (which regulates which cells produce prolactin) has two putative binding sites. The cloning and sequencing of these regulatory regions of the turkey prolactin gene will now permit molecular studies which may determine how prolactin synthesis is initiated and regulated. This knowledge should improve our understanding of the genetic and environmental factors that cause some turkey hens to cease egg production prematurely.
Two overlapping recombinant lambda phages containing the turkey prolacin gene were isolated from a turkey genomic library. The turkey prolactin gene consists of five exons and four introns, spanning approximately 6.7 kb. A major transcription start site was located by primer extension 52 nt up- stream of the initiator methhionine codon. Analysis of 2 kb of 5' flanking region failed to identify the consensus sequence for the estrogen response element. However, two regions similar to mammalian Pit-1/GHF-1 binding were identified.