DISTRIBUTION OF 5-METHYLCYTOSINE-RICH REGIONS IN THE METAPHASE CHROMOSOMES OF VICIA-FABA

The DNA methylation pattern of Viola faba metaphase chromosomes was ex amined with a specific monoclonal antibody. 5-methylcytosine (5-mC) re sidues are present in different chromosomal sites, and are particularl y abundant in telomeric and/or subtelomeric regions and in certain int ercalary bands. Chromosomal localization of methylated regions enables a better knowledge of the lengthwise differentiation of this chromoso me complement. Our results also indicate that there may be differences in monoclonal antibody binding between corresponding regions of homol ogous chromosomes in V. faba. This behaviour is detectable in specific regions with different frequencies. The data support results previous ly obtained for Allium cepa metaphase chromosomes using the same monoc lonal antibody.