In the Great East Japan Earthquake, a large amount of radioactive material was released due to the Fukushima Daiichi Nuclear Power Plant accident.Of these, "cesium-30," which has a half-life of 137 years, remains in the environment for a long period of time, so there are concerns about its impact on wildlife.
In investigating the effects of radiation, mice with high fertility and high levels of contamination by radioactive substances are used as models.It is also known that the testis is susceptible to radiation, that male germ cells in the testis cause cell death even at low radiation doses, and that radiation damage to germ cell DNA increases sperm malformations. There is.
Therefore, Kitasato University, in collaboration with the University of Toyama and the National Institute for Environmental Studies, investigated the radiation effects on wildlife caused by the nuclear accident, using the red rat that inhabits Japan as a model. In 2013 and 2014, 2 male A. speciosus during the breeding season were captured at two locations in Fukushima Prefecture with different air dose rates, and in Aomori and Toyama prefectures, which are more than 300 km away from the Fukushima Daiichi Nuclear Power Plant and have low air dose rates. ,investigated.
First, when the air dose rate on the surface of the capture area, the concentration of cesium-137 in the soil, and the radiation dose in the body were measured except for the internal organs and testes of the rat, high values were detected in Fukushima, and both external and internal exposures were detected. It turned out to be highly influenced.
Here, when the cell death frequency of germ cells of mice and the incidence of sperm malformations were examined, no significant difference was found in the frequency of appearance at any of Fukushima, Aomori, and Toyama.In other words, at the time of the survey, even in Fukushima Prefecture, where the dose is high, there is no effect on the number of germ cells in mice, and there is no significant effect on sperm formation.
This result shows that even at high doses, there is no effect on the reproduction of A. speciosus, at least in the part derived from males. It is suggested that it will not decrease.
In the future, we plan to proceed with research on the point that radiation changes the intracellular DNA base sequence in the Japanese field mouse in Fukushima Prefecture.A paper summarizing this achievement is published in the English scientific journal "Scientific Reports".
