Sylvain Costes and our new Podcast member Allison Burrell have the pleasure to interview Asako Nakamura from Ibaraki University, a principal investigator working at the Department of Biological Production Science in Ibaraki-ken, Japan. This is a special vodcast done at the Radiation Research Society meeting in Las Vegas in September 2014 where Dr. Asako Nakamura presented a poster describing how the DNA double strand break foci assay can be used to identify populations continuously exposed to ionizing radiation in and around Fukushima. For that purpose, blood from cows located in various sites around Fukushima were tested for DNA damage and compared to control groups. This work highlights the usefulness of biomarkers to identify exposed populations after a nuclear accident.
The abstract: The Fukushima Daiichi Nuclear Power Plant (FNPP) accident was one of the worst nuclear disasters in human history and resulted in widespread radiation contamination over large habitable areas. Several studies have documented the distribution of radionuclides in soil samples and animal organs throughout the contaminated region. However, assessing how such contamination affects the health of living organisms requires different techniques. One key consequence of ionizing radiation is the induction of DNA damage. One type of DNA damage, the double-strand break (DSB) can be sensitively quantitated utilizing the induced phosphorylation of histone H2AX at DSB sites. The creation of a DNA DSB in eukaryotic cells is generally accompanied by the formation of hundreds of phosphorylated H2AX (γ-H2AX) molecules in the chromatin flanking the DSB site. Antibodies to γ-H2AX allow the visualization of a "focus" at the DSB site. These foci form the basis of many biodosimetry assays used in both basic and clinical research to quantify radiation-induced DSBs. One of these assays utilizes lymphocytes in blood samples taken non-invasively by phlebotomy. Here, we evaluate the biological effects of the radiation fallout in the region surrounding the FNPP by quantifying DSBs in blood lymphocytes taken from cattle grazing in the exclusion zone. Our finding reveal that a greater than two-fold increase in fraction of damaged lymphocytes is observed in all cohorts within the 20 km exclusion zone in Fukushima. While levels of DNA damage slightly decrease over 700-days period of sample collection, the extent of damage appeared to be independent of the distance from the accident site within the exclusion zone. This study is the first to evaluate the biological impact of the accident utilizing the γ-H2AX assay.