A single blastomere sexing of caprine embryos by simultaneous amplification of sex chromosome-specific sequence of SRY and amelogenin genes

The primary objective of this study was to develop a simplified, rapid and authenticated protocol for sexing of caprine embryos. Polymerase chain reaction (PCR) is a powerful tool in preimplantation sex diagnosis, using embryo biopsy at the early developmental stage. Based on the amelogenin gene located on the conserved region of the sex chromosome, a primer pair was used and PCR was established to amplify a 262-bp fragment from the Xchromosome in female goat embryos and 262-bp fragments from the X chromosome and 202-bp fragments from the Y chromosome in male embryos. To validate the reliability of PCR, using the sex-determining region Y (SRY) gene located on the conserved region of Y chromosome, a primer pair was used and PCR was established to amplify a 122-bp fragment specific to the Y chromosome in male embryos. The in vitro-produced goat in vitro fertilisation (IVF)-embryos were made zona free by treating with pronase. The cell number in each embryo was counted before sexing. A single blastomere taken from these embryos was directly used as a template in PCR containing SRY and amelogenin gene-specific primers separately. Of 75 pronase-treated and 60 micromanipulated goat IVF embryos, 33 (44%) and 26 (43.33%) were confirmed as male and 42 (56%) and 34 (56.66%) as female, respectively. The sex-diagnosed embryos were kept in research vitro cleavage (RVCL) medium, and developed into 42.66% and 61.66% morulae and 13.33% and 23.33% blastocysts among pronase-treated and micromanipulated embryos, respectively. The AMELX gene-specific primer served as the internal control and did not interfere with amplification of the Y-specific sequence. In conclusion, a single blastomere sexing protocol based on the SRY and the amelogenin gene is simple, rapid, sensitive and efficient for sex determination in caprine early stage embryos.