Ttransgenerational transmission of epigenetic effects by small mammals' migrants from radiocontaminated zone

Up to now there is a distinct lack of quantitative data on the real long-term biological consequences of chronic radiation exposure lasting a long period of time. Patterns of transgenerational transmission of radiation exposure' biological effects insufficiently studied. This work we used the new method of small mammals' group biomarking with rhodamine B (RB) to evaluate: 1) animals' migrations beyond Eastern Urals Radioactive Trace zone (Kyshtym Accident 1957, Southern Urals) to adjacent areas; 2) to check the suitability of biomarker' transgenerational transmission to offspringthrough mothers' milk. Animal body structures containing keratin (claws, vibrissae, fur) are marked by this dye and detected by yellow fluorescence under green light. Received data demonstrate migrants of different ecological specialization (mice, voles, shrews) in adjacent area. First time we have revealed shrews-migrants (overwintered pregnant females) to control plot (more than 9000 m). The share of all small mammals' migrants to contiguous territories varies from 5% up to 30% in different monitoring seasons. Presence of different sex and functional status individuals in structure of migrants was shown. We revealed juvenile mice and shrews (Apodemus agrarius, Sylvaemus uralensis, Sorex araneus) which received RB with mother's milk. In all cases this label was treated as systemic. Transgenerational transmission of RB through mothers' breast milk in animals from natural populations is assumed as a solid evidence of real possibility of epigenetic effects' transference. The literature discusses the epigenetic effects of breastfeeding in two ways through micro RNA and genomic DNA methylation, which, in turn, can mediate a wide range of long-term effects on the development and health. Thus, the presence of labeled individuals of small mammals of different taxa, who received a biomarker with milk, is a real basis to make a conclusion about transgenerational channel for transmitting epigenetic effects, stemming from exposure, to vertebrates' offspring in adjacent areas. This work performed as part of a State Contract of the Institute Plant and Animal Ecology UB RAS and partly supported by the RFBR (project No. 20-04-00164).