Histone H3 trimethylation at lysine 9 marks the inactive metaphase X chromosome in the marsupial Monodelphis domestica.
In somatic cells of female marsupial and eutherian mammals, X chromosome inactivation (XCI) occurs. XCI results in the transcriptional silencing of one of the two X chromosomes and is accompanied by specific covalent histone modifications attributable to the inactive chromatin state. Because data about repressed chromatin of the inactive X chromosome (Xi) in marsupials are sparse, we examined in more detail the distribution of active and inactive chromatin markers on metaphase X chromosomes of an American marsupial, Monodelphis domestica. Consistent with data reported previously both for eutherian and marsupial mammals, we found that the Xi of M. domestica lacks active histone markers-H3K4 dimethylation and H3K9 acetylation. We did not observe on metaphase spreads enrichment of the Xi with H3K27 trimethylation which is involved in XCI in eutherians and was detected on the Xi in the interphase nuclei of mature female M. domestica in an earlier study. Moreover, we found that the Xi of M. domestica was specifically marked with H3K9 trimethylation, which is known to be a component of the Xi chromatin in eutherians and is involved in both marsupials and eutherians in meiotic sex chromosome inactivation which has been proposed as an ancestral mechanism of XCI.
Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russian Federation.
Irina S
IS
Zakharova
Alexander I
AI
Shevchenko
Alexander G
AG
Shilov
Tatyana B
TB
Nesterova
John L
JL
Vandeberg
Suren M
SM
Zakian
D000818:Animals; D002460:Cell Line; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D005260:Female; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism*; D008297:Male; D008677:Metaphase; D008745:Methylation; D048309:Monodelphis / Q000235:genetics* / Q000378:metabolism*; D014960:X Chromosome / Q000235:genetics* / Q000378:metabolism; D049951:X Chromosome Inactivation
D002843:Chromatin; D006657:Histones; D008239:Lysine