Late DNA replication of X chromosomes in female and pseudofemale cells ofMicrotus agrestis

✍ Scribed by F. Pera; P. Scholz

• Publisher: Springer
• Year: 1975
• Tongue: English
• Weight: 510 KB
• Volume: 30
• Category: Article
• ISSN: 0340-6717
• DOI: 10.1007/bf00291950

✦ Synopsis

The late replication pattern of the short arms of the X chromosomes of Microtus agrestis was studied in female cells and in cells with 2 X chromosomes of male origin by means of the BUdR-Giemsa technique and of 3H-thymidine labelling. The light absorption of Giemsa stained chromosome sections which were unifilarly substituted with BUdR (labelled), was found to be 59.2% of that of unlabelled chromosomes. In female cells, asynchrony of DNA replication of both X chromosomes indicated the presence of facultative heterochromatin in the X2 and euchromatin in the X1. In the male cells only euchromatic X chromosomes were observed in diploid XX and XO cells as well as in triploid XXY, XX and XO cells. The results show that inactivation of an X chromosone in vitro, in cells with more than one originally active X chromosome does not occur even after a culture duration of several years.