Vol 43, No 3 (2005)
Original paper
Published online: 2011-08-22
Rumex acetosa Y chromosomes: constitutive or facultative heterochromatin?
Folia Histochem Cytobiol 2005;43(3):161-167.
Abstract
Condensed Y chromosomes in Rumex acetosa L. root-tip nuclei were studied using 5-azaC treatment and immunohistochemical
detection of methylated histones. Although Y chromosomes were decondensed within root meristem in vivo, they
became condensed and heteropycnotic in roots cultured in vitro. 5-azacytidine (5-azaC) treatment of cultured roots caused transitional
dispersion of their Y chromosome bodies, but 7 days after removal of the drug from the culture medium, Y heterochromatin
recondensed and again became visible. The response of Rumex sex chromatin to 5-azaC was compared with that of condensed
segments of pericentromeric heterochromatin in Rhoeo spathacea (Sw.) Stearn roots. It was shown that Rhoeo chromocentres,
composed of AT-rich constitutive heterochromatin, did not undergo decondensation after 5-azaC treatment. The Y-bodies
observed within male nuclei of R. acetosa were globally enriched with H3 histone, demethylated at lysine 4 and methylated
at lysine 9. This is the first report of histone tail-modification in condensed sex chromatin in plants. Our results suggest that
the interphase condensation of Y chromosomes in Rumex is facultative rather than constitutive. Furthermore, the observed response
of Y-bodies to 5-azaC may result indirectly from demethylation and the subsequent altered expression of unknown genes controlling
tissue-specific Y-inactivation as opposed to the global demethylation of Y-chromosome DNA.
Keywords: Y chromosomesHeterochromatinMethylationHistone H3Rumex
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