Sex diagnosis of equine preimplantation embryos using the polymerase chain reaction.

This research article presents a reliable and quick method for determining the sex of equine embryos before implantation, using an enzyme to distinguish sex differences amplified through the Polymerase Chain Reaction.

Objective of the Study

• The main aim of this study is to identify an enzyme that would differentiate between male and female horses by finding a polymorphic restriction site between the ZFY and ZFX homologues. These homologues are amplified by the Polymerase Chain Reaction (PCR), a method to create millions of copies of a DNA sequence for identification purposes.

Methodology

• The researchers tested 38 different restriction enzymes using DNA extracted from the blood of both male and female horses.
• The enzyme Bsm I was identified as the only enzyme yielding different banding patterns in female and male DNA, thus making it unique in distinguishing between the sexes.
• Additionally, the primers, short strands of DNA that serve as starting points for PCR, were selected from conserved sequences between human ZFY and ZFX genes and mouse Zfy-1 and Zfy-2 genes. These genes are necessary for male sexual development.

Testing on Embryonic Cells

• Researchers used the Bsm I enzyme to test the method on embryonic cells. They obtained 17 horse “demi-embryos” (half embryos) from expanding blastocysts—early-stage embryos—at varying diameters.
• These demi-embryos were further divided into 3 to 7 parallel samples, which were individually analyzed to test the repeatability of the method.
• The sex of eight of the original embryos were diagnosed as female and nine as male. None of the samples showed inaccuracies within the embryonic samples.

Conclusion

• The study resulted in a method that can accurately and reliably predict the sex of horse embryos prior to implantation.
• This innovation could have significant implications for the equine industry, allowing for selective breeding programs and possibly improving the health and quality of the horse population over time.