Med. Weter. 68 (7), 391-396, 2012

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Strachecka A., Paleolog J., Borsuk G., Olszewski K., Bajda M..
DNA methylation in the honey bee (Apis mellifera) and its importance for biological research
The honey bee is the fourth insect – following the drosophila, the silkworm and the anopheles – whose genome has been fully investigated. Eighty percent of the methylation-prone apian genes are located in the brain. Only about 70 thousand out of the 60 million cytosines contained in the bee genome are methylated. Most of them have their primary methylation sites in the exons. In contrast to the intensive human genome methylation, only small and specific segments of the honey bee genome are methylated. It is estimated that approximately 35-40% of apian genes are deficient in CpG groups. DNA methylation increases the incidence of mutations at the CpG sites and may promptly lead to inconsistency between DNA sequences. Methylation in A. mellifera occurs exclusively in CpG dinucleotides characterized by a bimodal configuration and deamination of methylated CpGs to TpGs (CpA in the supplementary strand), resulting in GC mutating into AT. Genes with a low and high CpG content (low-CpG and high-CpG) are active in various biological processes. The low-CpG genes are typical of hypermethylation and particularly important for metabolism, ubiquitination, gene expression and translation. The high-CpG genes, in turn, primarily participate in hypomethylation and are fundamental for development processes, intercellular communication and adhesion. The sparing methylation system (of bees) offers unique possibilities for the study of methylation using a model organism that is much simpler than most laboratory plants and animals, let alone man. The specific epigenetic mechanisms active in the small apian genome make bees potential model objects for epigenetic analyses and experiments aiming at providing solutions to such human health problems as neoplastic, genetic, metabolic, vascular, neurological and immunological diseases. .
Key words: DNA importance, Apis mellifera, epigenome, genome, model organism