X-chromosome inactivation ensures dosage compensation for X-linked genes products in mammals. In eutherian mammals, X inactivation is controlled by the non-coding Xist transcript and is believed to be random, with either the paternal or maternal X chromosome being chosen for silencing. In mice, where most studies on the developmental timing of X inactivation have been conducted, Xist expression...

X-chromosome inactivation ensures dosage compensation for X-linked genes products in mammals. In eutherian mammals, X inactivation is controlled by the non-coding Xist transcript and is believed to be random, with either the paternal or maternal X chromosome being chosen for silencing. In mice, where most studies on the developmental timing of X inactivation have been conducted, Xist expression...

One of the two X chromosomes in each somatic cell of normal human females becomes inactivated very early in embryonic development. Although the inactivation of an X chromosome in any particular somatic cell of the embryonic lineage is thought to be a stochastic and epigenetic event, a strong genetic influence on this process has been described in the mouse. We have attempted to uncover evidence...

Markov segmentation is a method of identifying compositionally different subsequences in a given symbolic sequence. We have applied this technique to the DNA sequence of the human X chromosome to analyze its compositional structure. The human X chromosome is known to have acquired DNA through distinct evolutionary events and is believed to be composed of five evolutionary strata. In addition, i...

In mammals, X-chromosome inactivation occurs in all female cells, leaving only a single active X chromosome. This serves to equalise the dosage of X-linked genes in male and female cells. In the mouse, the paternally derived X chromosome (X(P)) is imprinted and preferentially inactivated in the extraembryonic tissues whereas in the embryonic tissues inactivation is random. To investigate how X(...

Early in the development of female mammals, one of the two X chromosomes is silenced in half of cells and the other X chromosome is silenced in the remaining half. The basis of this apparent randomness is not understood. We show that before X-inactivation, the two X chromosomes appear to exist in distinct states that correspond to their fates as the active and inactive X chromosomes. Xist and T...

Using genetic and cytogenetic markers, we assessed early development and X-chromosome inactivation (X-inactivation) in XX mouse androgenones produced by pronuclear transfer. Contrary to the current view, XX androgenones are capable of surviving to embryonic day 7.5, achieving basically random X-inactivation in all tissues including those derived from the trophectoderm and primitive endoderm tha...

Mammals exhibit two epigenetic phenomena whose consequence is the silencing of one of two wild-type copies of a gene X chromosome inactivation in females and parental imprinting of selected autosomal genes. As the mechanisms underlying these forms of gene dosage control are being elucidated, some striking similarities between them are being revealed. Of these similarities, none is more curious ...

The initiation of X-chromosome inactivation in female mammals is controlled by a key locus, the X-inactivation centre (Xic). The Xist gene, which maps to the candidate region for Xic and is expressed exclusively from the inactive X chromosome, is thought to be an essential component of the Xic. To test whether sequences spanning several hundred kilobases and including Xist from the Xic region a...

X inactivation is the silencing one of the two X chromosomes in XX female mammals. Initiation of this process during early development is controlled by the X-inactivation centre, a complex locus that determines how many, and which, X chromosomes will be inactivated. It also produces the Xist transcript, a remarkable RNA that coats the X chromosome in cis and triggers its silencing. Xist RNA coa...