Amplification of the Sry gene allows identification of the sex of mouse preimplantation embryos

Abstract

The Sry gene is key in determining male testis formation located in the sex-determining region of the Y chromosome during gonadal differentiation. In the present study, the Sry gene, chosen as the Y-specific target sequence, was amplified in order to sex mouse preimplantation embryos rapidly using the polymerase chain reaction (PCR). Meanwhile, the actin gene on the autosome was also amplified and served as a control for both male and female samples. When genomic DNA of male and female origin was amplified with Sry and actin primers, a 504 bp fragment was detected in both samples, while a 227 bp product was observed in only the male DNA. Morula and blastocyst stage embryos (n=135) were typed either as male or female with the exception of 2 samples. The Sry gene fragment was detected in about half of the embryos, which showed a 1:1 male and female ratio (P > 0.05). Based on developmental rates of embryos during morula and blastocyst stages, approximately 65% of faster-developing embryos were diagnosed as male and 63% of slower-developing embryos as female. The products of PCR were confirmed by restriction mapping and indicated that the sex of a preimplantation embryo can be determined accurately by amplifying the Sry gene. Use of this method would allow animal breeders to determine the sex of other mammalian preimplantation embryos before transfer to recipient females.