Int. J. Dev. Biol. 43: 69 - 73 (1999)

Vol 43, Issue 1

Pgk1 and Hprt gene activity in the peri-implantation mouse embryo is influenced by the parental origin of the X-chromosome

Published: 15 January 1999

K Sturm, M Lafferty and P P Tam

Embryology Unit, Children's Medical Research Institute, Wentworthville, NSW, Australia.

Abstract

The activity of two X-linked genes, Pgk1 and Hprt, that are localized on X-chromosomes of different parental origins in the XX mouse embryo was analyzed by the quantification of allele-specific transcripts. For the Pgk1 gene, the maternal allele-specific transcripts were consistently more abundant than the paternal transcripts in the blastocyst and the late gastrula. For the Hprt gene, the Hprt(b) allele was preferentially expressed in the blastocysts when it is present on the maternal X-chromosome. However, this skewed expression of the maternal allele was not observed in the reciprocal situation when the Hprt(a) allele was on the maternal X-chromosome. Like the Pgk1 locus, significantly more maternal Hprt transcripts were found in the gastrula-stage embryos irrespective of their genotypes. One possible interpretation of these results is that, in the XX mouse embryos, the genetic loci on maternal X-chromosome may be transcriptionally more active than their paternal counterparts during peri-implantation development.