Study of acetylated histone h3k9 – an active chromatin mark – in chromosomes from adult and fetal human lymphocytes

Background: Incorrect epigenetic modifications of the human genome may result in epigenetic disorders, thus, highlighting the necessity of studying chromosome epigenetic patterns in human development. Aim of the study: A comparative analysis of acetylated histone H3K9 (AcH3K9) patterns in human metaphase chromosomes from the lymphocytes of adults and fetuses. Materials and methods: The immunocytochemical detection of AcH3K9 in the metaphase chromosomes from PHA-stimulated peripheral lymphocytes of 13 adults and cord blood lymphocytes of 10 fetuses at 20-22 weeks of gestation. Results: Both in the chromosomes of the adults and the fetuses, AcH3K9 accumulated in the R- and T-, but not G-bands and avoided the regions of pericentromeric heterochromatin of the chromosomes 1, 9 and 16. When comparing the adult and the fetal chromosomes, different levels of AcH3K9 were revealed in a few bands: 2q31, 5p13, 5p15 and 16p13 had higher level of Н3К9 acetylation in adults, in contrast to 9q13 which was hyperacetylated in fetuses. Conclusion: The АсН3К9 distribution in metaphase chromosomes is band-specific and is similar between the adults and the fetuses, excluding a few bands with different acetylation levels.