Exchange of genetic information between therian X and Y chromosome gametologs in old evolutionary strata

Abstract

Therian X and Y sex chromosomes arose from a pair of autosomes. Y chromosomes consist of a pseudoautosomal region that crosses over with the X chromosome and a male‐specific Y‐chromosomal region that does not. The X chromosome can be structured into “evolutionary strata”. Divergence of X‐chromosomal genes from their gametologs is similar within a stratum, but differs among strata, likely caused by a different onset of suppression of crossing over between gametologs. After stratum formation, exchange of information between gametologs has long been believed absent; however, recent studies have shown limited exchange, likely through gene conversion. Herein we investigate exchange of genetic information between gametologs in old strata that formed before the split of Laurasiatheria (cattle) from Euarchontoglires (primates and rodents) with a new phylogenetic approach. A prerequisite for our test is an overall preradiative topology, that is, all X‐chromosomal gametologs are more similar among themselves than to Y‐chromosomal sequences. Screening multiple sequence alignments of the coding sequences of genes from cattle, mice, and humans identified four genes, DDX3X/Y,RBMX/Y,USP9X/Y, and UTX/Y, exhibiting a preradiation topology. Applying our test, we detected exchange of genetic information between all four X and Y gametologs after stratum formation.

Sex Determination Using RNA-Sequencing Analyses in Early Prenatal Pig Development

“…The Y chromosome harbors genes that are essential for testis development and function, such as the master gene for testis determination (SRY), which is expressed during a critical period of embryonic development, and other genes that are important for spermatogenic function, as the ZFY, EIF1AY and KDM5D. The importance of these Y-linked genes during male development has been elucidated for mammals [31][32][33][34]. These genes are located in the non-recombining region of the Y chromosome (NRY), which is also known as the male-specific Y (MSY) region, transmitted from fathers to sons without recombination with the X chromosome [35].…”

Convergent evolution of linked mating-type loci in basidiomycete fungi

“…In C. neoformans, gene conversion occurred in a GC-rich intergenic region within the MAT locus and was proposed as a mechanism for maintaining functionality of those genes within the MAT locus that are essential [39]. Gene conversion has also been observed in regions with suppressed recombination in the mating-type chromosomes of N. tetrasperma, in the mating type locus of the green algae Chlamydomonas reinhardtii, and in sex chromosomes of animals [95][96][97][98][99][100][101].…”

Reorganization of the Y Chromosomes Enhances Divergence in Israeli Mole Rats Nannospalax ehrenbergi (Spalacidae, Rodentia): Comparative Analysis of Meiotic and Mitotic Chromosomes

“…A genetic linkage for male-specific genes was selected as soon as male-determining genes emerged on a proto-Y chromosome [ 11 , 12 , 13 , 14 , 15 ]. The dark side of the specialization appeared to be a deficiency in recombination due to the absence of homological regions between X and Y chromosomes, the declining force of natural selection, accumulating deleterious mutations, and further degradation of the Y chromosome [ 16 , 17 , 18 ].…”