Hydroxyurea and Caffeine Impact pRb-like Protein-Dependent Chromatin Architecture Profiles in Interphase Cells of Vicia Faba

The survival of cells depends on their ability to replicate correctly genetic material. Cells exposed to replication stress can experience a number of problems that may lead to deregulated proliferation, the development of cancer, and/or programmed cell death. In this article, we have induced prolonged replication arrest via hydroxyurea (HU) treatment and also premature chromosome condensation (PCC) by co-treatment with HU and caffeine (CF) in the root meristem cells of Vicia faba. We have analyzed the changes in the activities of retinoblastoma-like protein (RbS807/811ph). Results obtained from the immunocytochemical detection of RbS807/811ph allowed us to distinguish five unique activity profiles of pRb. We have also performed detailed 3D modeling using Blender 2.9.1., based on the original data and some final conclusions. 3D models helped us to visualize better the events occurring within the nuclei and acted as a high-resolution aid for presenting the results. We have found that, despite the decrease in pRb activity, its activity profiles were mostly intact and clearly recognizable, with some local alterations that may correspond to the increased demand in transcriptional activity. Our findings suggest that Vicia faba’s ability to withstand harsh environments may come from its well-developed and highly effective response to replication stress.

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.

ALDEHYDE DEHYDROGENASE 1L1 IN RAT BRAIN CELLS

Aldehyde dehydrogenase belonging to family 1, member L1 (Aldh1L1) is one of the most important enzymes called astrocytes that determine such important functions of these cells as participation in folate metabolism and inactivation of formiate in the CNS. The aim of this study was immunocytochemical detection of cells synthetizing Aldh1L1 in rat brain, and determination of their topography and morphology features. The brain of adult male Wistar rats (n=10) was used at the work. The material was fixed in zinc-ethanol-formaldehyde, a special fixative providing high preservation of antigenic determinants. It was shown that A ldh1L1 is detected in all brain anatomic structures. Among brain cells expressing Aldh1L1 macroglia cells - astrocytes and ep-endymocytes - were identified. In astrocytes the most intensive immunohistochemical reaction was observed in the endfeets of processes of these cells and in superficial astrocytes forming the superficial glial border membrane. In ependymocytes, the product of immune reaction was detected in the cytoplasm as numerous granules of various shapes and size (from 0.1x0.2 to 1.3X3.7 pm). The predominant localization of Aldh1L1 in brain cells involved in transport of substances through blood-brain, CSF-brain, and CSF-blood barriers allows one to expect that this protein will prove to be useful functional marker during experimental investigations of the CNS barrier system and evaluating the reaction of brain to toxic metabolic products of alcohol surrogates.