Polymerase chain reaction-heteroduplex (PCR-HD) polymorphism within the bovine STAT5A gene

Signal transducers and activators of transcription (STATs) are transcription factors mediating signals of various hormones and cytokines. STAT5A, previously known as the mammary gland factor (MGF), mediates the action of prolactin on milk protein gene expression in mammary epithelial cells. We used polymerase chain reaction-heteroduplex (PCR-HD) and sequencing methods for detection of nucleotide sequence polymorphism in intron 15 of the bovine STAT5A gene. A 281-bp gene fragment, from nt 12525 to nt 12806 (GenBank AJ 237937), was amplified with PCR, denatured and subjected to polyacrylamide gel electrophoresis to detect PCR-HD polymorphism. Three genotypes and two alleles were identified. DNA samples derived from homozygotes AA and BB were sequenced. A trinucleotide CCT deletion was found in the variant B of the STAT5A gene at position 12549. In a group of 72 beef bulls of various breeds and 49 Friesian bulls genotyped by PCR-HD mostly the AA genotype was found (from 83 to 61% depending on breed). The frequency of allele A varied between 0.91 and 0.77. Animals of genotype BB were found in Charolaise and Limousine breeds only.