IMMUNOCYTOCHEMICAL ANALYSIS OF HUMAN METAPHASE CHROMOSOME METHYLATION STATUS
A. A. Pendina,1 O. A. Efimova,2 A. N. Kaminskaya,2 T. V. Kuznetzova,1
V. S. Baranov 1
1 D. O. Ott's Institute of Obstetrics and Gynecology, RAMS, St. Petersburg, and
2 Department of Genetics and Breeding, St. Petersburg State University, St. Petersburg, Russia;
e-mail: pendina@mail.ru
The present paper describes a distribution of 5-methylcytosine-rich DNA in human metaphase chromosomes from PHA-stimulated lymphocytes.
Immunocytochemical detection of 5-methylcytosine was carried out with monoclonal antibodies. Fluorescent signals were preferentially localized in certain chromosomal
regions, corresponding to R-, some T-bands, pricentromeric heterochromatin, and short arms of acrocentric chromosomes. Specificity of fluorescent signals distribution
along chromosomes allowed to describe a new type of human metaphase chromosomes banding pattern, which we call M-banding. Specific M-markers of landmarks
were identified for each chromosome pair. The analysis of M-bands methylation status was carried out taking into account data available in literature on their nucleotide
structure features, namely GC-rich H3 isochore content and CpG-islands concentration. According to our results, a high level of methylation is typical for the majority
of GC-rich regions. However, certain bands of 6, 9, 10, 13, 15 chromosomes (6ql5, 6q21, 6q23, 9pl3, 9p22, 9p32, 10q24, 13q22, 15ql5, 15q24) were shown to be
hypomethylated, suggesting their special functional status in lymphocytes.
Key words: DNA methylation, 5-methylcytosine, human metaphase chromosomes, GC-rich DNA, heterochromatin
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