Xist RNA is associated with the transcriptionally inactive XY body in mammalian male meiosis.
In eutherian mammals, X inactive-specific transcripts (Xist) are expressed in somatic cells possessing more than one X chromosome, and in germline cells of males, in which the single X chromosome is transcriptionally inactive. In early meiosis of males the sex chromosomes form an inactive XY nuclear compartment (XY body). We show by in situ reverse-transcribed polymerase chain reaction that Xist RNA is concentrated in the XY body. This fine localization suggests that Xist RNA is involved in inactivation of the male X chromosome, and that it has spreading capability, not only in cis but also in a quasi-cis mode, to juxtaposed non-X chromosomes. A hypothetical scheme links the evolution of heteromorphic sex chromosomes to the development of X condensation/inactivation in the male. The mechanism of X inactivation in somatic cells of mammalian females, resulting in male/female dosage compensation, has been recruited from the Xist-activated chromosome condensation machinery that developed in male meiosis earlier in evolution.
Ayoub
N
N
Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Richler
C
C
Wahrman
J
J
D000818:Animals; D002467:Cell Nucleus / Q000235:genetics / Q000648:ultrastructure; D002874:Chromosome Mapping; D004303:Dosage Compensation, Genetic; D005260:Female; D006801:Humans; D017403:In Situ Hybridization / Q000379:methods; D008297:Male; D008322:Mammals / Q000235:genetics*; D008540:Meiosis; D051379:Mice; D008810:Mice, Inbred C57BL; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D012730:Sex Chromosomes / Q000235:genetics*; D013737:Testis / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D014157:Transcription Factors; C077885:XIST non-coding RNA; D012313:RNA