title: DNA methylation of the X chromosomes of the human female: an in situ semi-quantitative analysis.
abstract: We present an in situ semi-quantitative analysis of the global DNA methylation of the X chromosomes of the human female using antibodies raised against 5-methylcytosine. The antibodies were revealed by immunofluorescence. Images were recorded by a CCD camera and the difference in intensity of fluorescence between active (early replicating) and inactive (late-replicating) X chromosomes was measured. Global hypomethylation of the late-replicating X chromosomal DNA was observed in three cases of fibroblast primary cultures that were characterized by numerical and structural aberrations of the X chromosomes [46,X,ter rea(X;X), 48,XXXX and 46, X,t(X;15)]. In these cases, the difference between early and late-replicating X chromosomes was significantly greater than the intra-metaphasic variations, measured for a pair of autosomes, that result from experimental procedures. In cells with normal karyotypes, the differences between the two X chromosomes were in the range of experimental variation. These results demonstrated that late replication and facultative heterochromatinization of the inactive X are two processes that are not related to global hypermethylation of the DNA.
authors.affiliation: Institut Curie, UMR 147, CNRS, Cytogénétique Moleculaire et Oncologie, 26 rue d'Ulm, F-75231 Paris Cedex 5, France.
authors.forename: J
authors.initials: J
authors.lastname: Bernardino
authors.forename: E
authors.initials: E
authors.lastname: Lamoliatte
authors.forename: M
authors.initials: M
authors.lastname: Lombard
authors.forename: A
authors.initials: A
authors.lastname: Niveleau
authors.forename: B
authors.initials: B
authors.lastname: Malfoy
authors.forename: B
authors.initials: B
authors.lastname: Dutrillaux
authors.forename: C A
authors.initials: CA
authors.lastname: Bourgeois
mesh_terms: D044503:5-Methylcytosine; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002478:Cells, Cultured; D003596:Cytosine / Q000031:analogs & derivatives* / Q000032:analysis / Q000276:immunology; D004247:DNA / Q000737:chemistry*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D004261:DNA Replication; D004303:Dosage Compensation, Genetic; D005260:Female; D005347:Fibroblasts / Q000648:ultrastructure; D019084:Fluorescent Antibody Technique, Indirect; D006570:Heterochromatin / Q000737:chemistry / Q000235:genetics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007621:Karyotyping; D008214:Lymphocytes / Q000648:ultrastructure; D008745:Methylation; D008856:Microscopy, Fluorescence; D000091402:Prohibitins; D011817:Rabbits; D012729:Sex Chromosome Aberrations / Q000378:metabolism; D014960:X Chromosome / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D006570:Heterochromatin; C000717331:PHB2 protein, human; D000091402:Prohibitins; D044503:5-Methylcytosine; D003596:Cytosine; D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases