Sex chromosomal transposable element accumulation and male-driven substitutional evolution in humans

We sequenced the genomic region containing the human Y-linkedzinc finger gene (ZFY). Comparison of ZFY to the related regionon the X chromosome (ZFX) and to autosomal sequences revealsa significant accumulation of transposable elements on the sexchromosomes. In addition, five times as many retroviruslikeelements (RLEs) are present in the ZFY region as in the ZFXregion. Thus, transposable elements accumulate more rapidlyon the sex chromosomes, and the insertion of RLEs may occurmore frequently in the male than in the female germ line. Whenthe accumulation of substitutions in Alu elements was analyzed,it was found that the Alu elements at the Y-chromosomal locusdiverged significantly faster than those at the X-chromosomallocus, whereas the divergence of autosomal Alu elements wasintermediate. The male-to-female mutation rate ratio was estimatedto be 2.5.