Porcine SRY Gene Locus and Genital Ridge Expression'

Porcine SRY gene locus was cloned through use of a strategy of anchored polymerase chain reaction (PCR) amplification from a male pig genomic DNA size-selected library constructed in a plasmid vector as well as 3 ' reverse transcription (RT)-PCR am-plification of porcine genital ridge SRYtranscripts. In total, 1664 bp of genomic DNA and 106 bp of 3 ' cDNA are presented. The open reading frame of porcine SRY consists of 624 bp repre-senting 208 amino acids (aa) with a centrally located HMG box domain of 79 aa, an amino-terminal region of 59 aa, and a car-boxy terminal of 70 aa. Structurally, porcine SRY resembles hu-man and bovine SRY more closely than it does mouse Sry, and it lacks the carboxy-terminal activation domain seen in the mouse Sry molecule. Similar to human and bovine testicular SRY transcripts, the porcine SRY genital ridge transcript has a rela-tively short 3 ' untranslated region (UTR), in contrast to the ex-tended UTR of the mouse genital ridge Sry transcript. The por-cine SRY gene is expressed within the cells of the genital ridge of the developing male pig embryo between Days 21 and 26 (e21-e26) of gestation, during which time the primitive gonads are bipotential, but not on Day e31, by which time male testis determination is histologically evident