[Chromosomal instability in rodents from the EURT territory: interspecies comparison]

Area of Science:

• Environmental Science
• Genetics
• Radiobiology

Background:

• The Eastern Urals Reserve (EURT) experienced significant radioactive contamination (500-1000 Ci/km2) following the 1957 Mayak plant accident.
• Strontium-90 (90Sr) pollution is a global concern in the Middle and South Urals and Transurals regions.
• Generations of common voles (Microtus arvalis) and mole voles (Ellobius talpinus) have lived in these contaminated areas.

Purpose of the Study:

• To assess the cytogenetic effects of chronic radioactive exposure on M. arvalis and E. talpinus populations.
• To investigate potential adaptive mechanisms or lack thereof in response to long-term 90Sr contamination.
• To compare genomic responses between two rodent species inhabiting radioactively polluted environments.

Main Methods:

• Trapping of M. arvalis and E. talpinus in the EURT and control populations.
• Measurement of internal dose rates from 90Sr and total accumulated doses from external and internal sources.
• Analysis of cytogenetic parameters: frequency of cells with chromosome aberrations and gaps, rates of aneuploidy and polyploidy.

Main Results:

• M. arvalis in EURT exhibited a significantly higher frequency of aberrant cells (4.57%) compared to control populations (0.44-0.86%).
• E. talpinus showed no significant increase in any cytogenetic parameters compared to control groups.
• Average internal dose rates from 90Sr were 0.413 mGy/day in M. arvalis and 0.985 mGy/day in E. talpinus.

Conclusions:

• Chronic 90Sr exposure induces significant cytogenetic damage in M. arvalis populations.
• The absence of a genomic response in E. talpinus suggests potential protective mechanisms, such as melanin-related metabolites or evolved heritable resistance.
• Genetic drift and selection in isolated E. talpinus demes may have contributed to the observed lack of cytogenetic aberrations.