Amplification of Porcine SRY Gene for Sex Determination

The separation of X and Y chromosome-bearing sperm is of use in many aspects of livestock maintenance. In this study, we sought to determine the difference in DNA content between X- and Y-bearing sperm, separate sperm into X- and Y-enriched pools, and assess the efficacy of sorting. Sperm collected from Duroc and miniature pigs were stained with 20.8 $\mu{M}$ Hoechst 33342 and analyzed using a high-speed cell sorter. Measurement of the fluorescence intensity of stained sperm nuclei revealed that the X-bearing sperm of Duroc and miniature pigs respectively contain 2.75% and 2.88% more DNA than Y-bearing sperm. In total, 50.18% of the sperm were assigned to the X-sorted sample and 49.82% was assigned to the Y-sorted sample for Duroc pigs. For miniature pigs, the Xsorted sample represented 50.19% of the population and the Y-sorted represented 49.81% of the population. Duplex PCR was used to evaluate accuracy of sorting. A fast and reliable method for porcine sexing was developed through amplification of the sex-determining region of the Y chromosome gene (SRY). Oligonucleotide primers were designed to amplify the conserved porcine SRY high motility group (HMG) box sequence motif. We found that the primer pair designed in this study was 1.46 times more specific than previously reported primers. Thus, this study shows that the present method can be applied in porcine breeding programs to facilitate manipulation of the sex ratio of offspring and to achieve precise sexing of porcine offspring by amplification of the HMG box of the SRY gene.