A possible active segment on the inactive human X chromosome

✍ Scribed by Eeva Therman; Gloria E. Sarto; C. Distèche; Carter Denniston

• Publisher: Springer
• Year: 1976
• Tongue: English
• Weight: 867 KB
• Volume: 59
• Category: Article
• ISSN: 0009-5915
• DOI: 10.1007/bf00328482

✦ Synopsis

An idic(Xp--) in which the two X chromosomes are attached short arm to short arm, and which thus has two b regions (the Q-dark segment next to the centromere on Xp) between the inactivation centers, assumed to be situated on the Q-dark region next to the centromere on Xq, showed 63.8% bipartite Barr bodies as compared with 22.2% formed by idic(Xq--). In addition, the mean distance of the two parts of the Barr bodies in the fibroblasts of a patient with idic(Xp--) is significantly greater than in the cases with one or no b region. Contrary to the other patients with abnormal X chromosomes, the buccal cells of a woman idic(Xp--) showed a number of bipartite Barr bodies. -- To explain these observations we have put forward the hypothesis that the b region on the Xp always remains active and thus, when the rest of the chromosome forms a Barr body, this segment is extended, allowing the two parts of the X chromatin to get farther apart and at the same time increasing the percentage of bipartite bodies.