Abstract
Exposure to ionizing radiation (IR) from radionuclides released into the environment can damage DNA. An expected response to exposure to environmental radionuclides, therefore, is initiation of DNA damage response (DDR) pathways. Increased DNA damage is a characteristic of many organisms exposed to radionuclides but expression of DDR genes of wildlife inhabiting an area contaminated by radionuclides is poorly understood. We quantified expression of five central DDR genes Atm, Mre11, p53, Brca1 and p21 in the livers of the bank vole Myodes glareolus that inhabited areas within the Chernobyl Exclusion Zone (CEZ) that differed in levels of background radioactivity, and also from control areas outside the CEZ (i.e. sites with no detectable environmental radionuclides) in Ukraine. Expression of these DDR genes did not significantly differ between male and female bank voles, nor among sites within the CEZ. We found a near two-fold upregulation in the DDR initiators Mre11 and Atm in animals collected from the CEZ compared with samples from control sites. As Atm is an important regulator of oxidative stress, our data suggest that antioxidant activity may be a key component of the defense against exposure to environmental radioactivity.
Highlights
Accidental release of radionuclides into the environment presents a potential health risk to humans and wildlife (Møller and Mousseau, 2006; Lourenço et al, 2016)
Liver was selected as the tissue of interest as it is radiosensitive in a clinical context (Christiansen et al, 2007; Stryker, 2007); liver tissue appears sensitive to DNA damage, with liver tissue from bank voles exposed to environmental radionuclides having shorter telomeres compared with samples from control areas (Kesäniemi et al unpublished)
Almost two-fold, upregulation in expression of Atm and Mre11 in the livers of bank voles living within the Chernobyl Exclusion Zone (CEZ), which is the first evidence that expression of DNA repair-related genes is stimulated in vertebrates exposed to low-dose environmental radioactivity
Summary
Accidental release of radionuclides into the environment presents a potential health risk to humans and wildlife (Møller and Mousseau, 2006; Lourenço et al, 2016). On 26 April 1986, reactor 4 of the Chernobyl Nuclear Power Plant (NPP) exploded, releasing an estimated 9 × 103 to 1 × 104 petabecquerels (Pbq) of radionuclides over much of Eastern Europe, Russia, and Fennoscandia (Dreicer et al, 1996). This accident, together with the accident at the Fukushima Daiichi NPP in 2011, stimulated public and scientific interest in the impacts of environmental radionuclides on natural ecosystems (Wheatley et al, 2016). The wildlife inhabiting the CEZ provide the best-studied model of the biological impact of exposure to radionuclides (Møller and Mousseau, 2006)
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