Hybridization properties of human X-chromosomal RNA transcripts from murine--human hybrids

A human--mouse hybrid cell line which has retained the human X chromosome and a fragment of chromosome 2 contains RNA sequences transcribed from human DNA. Nuclear RNA enriched for human sequences was prepared from this hybrid cell line by a multistep hybridization procedure to mouse and human DNA immoblized on nitrocellulose filters. The properties of this RNA were analyzed by RNA--DNA hybridization techniques. The results indicate that we have prepared a RNA fraction enriched for sequences homologous to repeated DNA sequences of the human X chromosome.