396 ISSN 1022-7954, Russian Journal of Genetics, 2019, Vol. 55, No. 3, pp. 396–398. © Pleiades Publishing, Inc., 2019. DNA Methylation in Yeast-Like Fungi of the Species Candida albicans Induced by Different Lengths of Exposure to Ozone 1 M. Gryzinska a, *, L. Wlazlo b, **, B. Nowakowicz-Debek b , G. Jezewska-Witkowska a , and A. Jakubczak a a Faculty of Biology, Animal Sciences and Bioeconomy, Institute of Biological Basis of Animal Production, University of Life Sciences in Lublin, Lublin, 20-950 Poland b Department of Animal Hygiene and Environmental Hazards, Faculty of Biology, Animal Sciences and Bioeconomy, University of Life Sciences in Lublin, Lublin, 20-950 Poland *e-mail: magdalena.gryzinska@up.lublin.pl **e-mail: lukasz.wlazlo@up.lublin.pl Received September 17, 2018; revised October 11, 2018; accepted October 17, 2018 Abstract⎯The objective of the study was to determine global DNA methylation induced by lengths of expo- sure to ozone in Candida albicans isolates of human and animal origin. The level of global DNA methylation was tested as the relative methylation level in the samples in relation to a methylated control. The analysis revealed differences in the methylation level in the human and animal samples. Ozone had a significant effect on the DNA methylation process, and longer exposure substantially increased the level of total methylated DNA. As expected, the degree of methylation depended on the length of exposure to ozone. Keywords: Candida albicans, epigenetics, global DNA methylation, ozone DOI: 10.1134/S1022795419030086 The DNA methylation reaction involves the exchange of hydrogen for a methyl group in the C5 position of the cytosine pyrimidine ring or the addi- tion of CH 3 to the amino group of adenine (N6) or cytosine (N4). Methylated cytosine is a significant epigenetic factor involved in regulating gene expres- sion. Its presence is crucial to the transfer of genetic information [1]. Transcriptionally active regions of the genome have a low content of methylated cytosine, whereas the presence of CpG within gene promoters may result in inhibition of transcription or expression of genes, as well as a loss of function by their products [2]. Each species has its own characteristic, strictly defined methylation sites which are its identification pattern. These sites undergo substantial changes during embryonic development and in the post-natal period [3, 4]. The methylation level is currently regarded as an indicator of the age and lifespan of organisms. When it proceeds in an abnormal manner, it may be the cause of premature aging [5]. However, not only DNA undergoes methylation; this process also affects all of the chromatin. Histone proteins, which make up nucleosomes, are subject to a variety of biochemical processes, including methyla- tion. Moreover, these proteins are highly conserved; their homologous domains have been detected in mammals, plants and fungi [6, 7]. Candida albicans is a major pathogenic organism in individuals with low immunity. An excessive number of yeasts and yeast-like fungi in the human body may be a precursor to diseases such as diabetes, asthma, gastroesophageal reflux disease, intestinal disorders such as leaky gut syndrome, irritable bowel syndrome, or ulcerative colitis, and other conditions, which often have non-specific symptoms and are difficult to diag- nose [8, 9]. Many biological processes in humans take place in a similar or the same manner as in other living organ- isms. However, not all in vivo studies can be carried out on human beings. For this reason a group of organisms has been identified in which certain biolog- ical characteristics are similar [10]. Therefore, research on DNA methylation in C. albicans may be a key to discoveries which will be significant in solving problems associated with the pathogenic nature of these fungi. The aim of the study was to determine the level of global DNA methylation induced by various lengths of exposure to ozone in Candida albicans iso- lates from humans and animals. The material for the study came from two cultures of Candida albicans acquired from humans and ani- mals. Each group consisted of 8 isolates. The Candida 1 The article is published in the original. SHORT COMMUNICATIONS