Asynchronous replication of constitutive heterochromatin on X chromosomes in female Mus dunni. Possible influence of facultative heterochromatin on the adjacent constitutive heterochromatin.
Euchromatin DNA of one X chromosome in mammalian females, which becomes facultatively heterochromatinized, is known to replicate asynchronously late in S phase compared to its active homologue. In the females of a pygmy mouse species Mus dunni, which has prominent segment of constitutive heterochromatin as the short arm of its submetacentric X chromosome, we have observed asynchronous replication of c-heterochromatin arm as well, predominant number of cells showing the segment associated with the facultatively heterochromatic X to be terminating later. The preferential later termination of replication of the c-heterochromatic arm on the "lyonized X" appears to be due to the influence of facultative heterochromatin on the adjacent constitutive heterochromatin.
D000818:Animals; D004261:DNA Replication; D005260:Female; D006570:Heterochromatin / Q000502:physiology*; D007621:Karyotyping; D008677:Metaphase; D051379:Mice / Q000235:genetics*; D012730:Sex Chromosomes / Q000502:physiology*; D014960:X Chromosome / Q000502:physiology*
D006570:Heterochromatin