During the development of female mammals, one of the two X chromosomes is inactivated, serving as a dosage-compensation mechanism to equalize the expression of X-linked genes in females and males. While the choice of which X chromosome to inactivate is normally random, X chromosome inactivation can be skewed in F1 hybrid mice, as determined by alleles at the X chromosome controlling element (Xc...

To investigate the evolution of the mammalian sex chromosomes, we have compared the gene content of the X chromosomes in the mammalian groups most distantly related to man (marsupials and monotremes). Previous work established that genes on the long arm of the human X chromosome are conserved on the X chromosomes in all mammals, revealing that this region was part of an ancient mammalian X chro...

Pluripotent stem cells can be classified into two distinct states, naïve and primed, which show different degrees of potency. One difficulty in stem cell research is the inability to distinguish these states in live cells. Studies on female mice have shown that reactivation of inactive X chromosomes occurs in the naïve state, while one of the X chromosomes is inactivated in the primed state. Th...

Inactivation of the X chromosome in the male germ line has been suggested to contribute to the excess of gene movement off the X chromosome and the paucity of X-linked male-biased genes that have been observed in Drosophila species. Recent experimental work has demonstrated the transcriptional inactivation of the X chromosome during spermatogenesis, but it is not known if some regions of the X ...

We describe the isolation and characterization of Aberrant X segregation (Axs), a dominant female-specific meiotic mutation. Although Axs has little or no effect on the frequency or distribution of exchange, or on the disjunction of exchange bivalents, nonexchange X chromosomes undergo nondisjunction at high frequencies in Axs/+ and Axs/Axs females. This increased X chromosome nondisjunction is...

eight accessions of thyme medicinal plant, belonging to iranian endemic thymus daënensis, t. eriocalyx, t. migricus and an unknown thymus spp species, were tested for karyotypic analysis, using squash technique and 2% (w/v) aceto-orcein staining method. chromosomal parameters examined were: short arm (s), long arm (l), total length of chromosome (tl), arm ratio (ar), r-value, total chromosome v...