Examination of Y Chromosome Linked Gene Expression in Healthy and Arrested Pre-implantation Bovine Embryos

Abstract

Sexual dimorphisms in growth rate and metabolism have been observed in the early embryo suggesting a role for sex chromosome linked gene expression in the early embryo. It is hypothesized that Y chromosome gene expression is aiding male embryo development in vitro. Reverse transcription polymerase chain reaction revealed the expression of DDX3Y, EIF1AY, TSPY, USP9Y, ZFY, and ZRSR2 in blastocysts but not HSFY or SRY. Furthermore DDX3Y, USP9Y, and ZRSR2Y showed expression in 100% of individual male blastocyst analysed. USP9Y and ZFY showed expression as early as the 4-cell and 8-cell stage however not in embryos arrested at the 2- to 8-cell stage. RNA interference to knock down the transcripts of USP9Y resulted in a significant decreased the cleavage rate but no significant difference in the blastocyst rate. Given Y linked gene expression coincidence with embryonic genome activation, and the absence of USP9Y and ZFY transcripts in the arrested embryos it was concluded that these genes may be important for early male embryo development.