The onset of X-chromosome inactivation was investigated cytologically in postimplantation female mouse embryos of age 5£, 6\ and 1\ days post-coitum (d.p.c.) and in the isolated epiblasts of 6 d.p.c. embryos before primitive streak formation using a heat/hypotonic technique to reveal the inactive X chromosome by differentially dark staining with Giemsa. The results indicate that X inactivation ...

We recently have identified a ubiquitously transcribed mouse Y chromosome gene, Uty , which encodes a tetratricopeptide repeat (TPR) protein. A peptide derived from the UTY protein confers H-Y antigenicity on male cells. Here we report the characterization of a widely transcribed X-linked homologue of Uty , called Utx , which maps to the proximal region of the mouse X chromosome and which detec...

BACKGROUND X chromosome inactivation, which silences gene expression from one of the two X chromosomes in females, is usually random. Skewed X inactivation has been implicated in both the expression and the suppression of X-linked disease phenotypes and has been reported to occur more frequently in breast and ovarian cancer patients, including BRCA1 or BRCA2 mutation carriers, than in control s...

Recurrent spontaneous abortion (RSA) defines as two or more consecutive losses at < or = 20 weeks of gestation and affects an estimated 1 of every 100 couples wishing to have children. However, it remains a poorly understood phenomenon. Recent reports observed a significant association between highly skewed X chromosome and RSA, supporting that X chromosome inactivation might be an important an...

Heterogametic sex chromosomes have evolved many times independently, and in many cases, the loss of functional genes from the sex-limited Y or W chromosome leaves only one functional gene copy on the corresponding X or Z chromosome in the heterogametic sex. Because gene dose often correlates with gene expression level, this difference in gene dose between males and females for X- or Z-linked ge...

X chromosome inactivation in eutherian mammals has been thought to be tightly controlled, as expected from a mechanism that compensates for the different dosage of X-borne genes in XX females and XY males. However, many X genes escape inactivation in humans, inactivation of the X in marsupials is partial, and the unrelated sex chromosomes of monotreme mammals have incomplete and gene-specific i...

T he function of BRCA1 is complex and includes roles in DNA damage repair, cell cycle control, regulation of transcription, and X chromosome inactivation. 2 TSIX is thought to control X chromosome inactivation by blocking the accumulation of XIST on the active X chromosome. BRCA1 co-localises with XIST inactive X chromosomes (Xi) and stabilises Xi. Because of this interaction, the loss of BRCA1...

T he function of BRCA1 is complex and includes roles in DNA damage repair, cell cycle control, regulation of transcription, and X chromosome inactivation. 2 TSIX is thought to control X chromosome inactivation by blocking the accumulation of XIST on the active X chromosome. BRCA1 co-localises with XIST inactive X chromosomes (Xi) and stabilises Xi. Because of this interaction, the loss of BRCA1...