Assessment of chromosome aberrations in large Japanese field mice (Apodemus speciosus) in Namie Town, Fukushima

Abstract

Purpose

After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in Japan on March 11 2011, the surroundings became contaminated with radionuclides. To understand the possible biological effects after chronic low dose-rate radiation in contaminated areas of Fukushima, we assessed the effects in large Japanese field mice (Apodemus speciosus) by means of chromosome aberration analysis.

Materials and methods

We collected A. speciosus in five sites around Namie Town, Fukushima (contaminated areas) and in two sites in Hirosaki City, Aomori (control areas, 350 km north of FDNPP) from autumn 2011 to 2013. The number of mice captured and ambient dose-rates were as follows: high (n = 11, 10.1–30.0 µGy h⁻¹), moderate (n = 10, 5.7–15.6 µGy h⁻¹), low (n = 12, 0.23–1.14 µGy h⁻¹) and control (n = 20, 0.04–0.07 µGy h⁻¹). After spleen extraction from rodents, spleen cell culture was performed to obtain metaphase spreads. Chromosome aberrations were assessed on Giemsa-stained metaphase spreads.

Results

Although the mice in the contaminated areas were chronically exposed, there was no radiation-specific chromosome aberrations observed, such as dicentric chromosomes and rings. Some structural aberrations such as gaps and breaks were observed, and these frequencies decreased annually in mice from Namie Town.

Conclusion

These findings suggest that chromosome aberration analysis is useful to evaluate and monitor radiation effects in wild animals.

Keywords:

• Fukushima
• large Japanese field mice
• chromosome aberration
• spleen cell

Acknowledgements

We express deep appreciation to the local government of Namie Town in Fukushima Prefecture, Japan for facilitating our study. We also thank Ikue Asari, Naomi Sasaki, Yuki Sato and the other members of the laboratory for their technical and secretarial support. Lastly, we would like to extend their gratitude to the reviewers for their constructive comments.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported in part by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) [Nuclear Energy S&T and Human Resource Development Project through concentrating wisdom, Grant Number JPMX 17S17942991].

Notes on contributors

Yohei Fujishima

Yohei Fujishima, Ph.D., is an assistant professor at Department of Radiation Biology, Tohoku University Grauduate School of Medicine.

Akifumi Nakata

Akifumi Nakata, Ph.D., is an associate professor at Faculty of Pharmaceutical Science, Department of Pharmacy, Hokkaido University of Science.

Risa Ujiie

Risa Ujiie, M.Sc., is a doctoral student at Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University

Kosuke Kasai

Kosuke Kasai, Ph.D., is a senior lecturer at Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences.

Kentaro Ariyoshi

Kentaro Ariyoshi, Ph.D., is an associate professor at the Integrated Center for Science and Humanities, Fukushima Medical University.

Valerie Swee Ting Goh

Valerie Swee Ting Goh, M.Sc., is a doctoral student at Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, and a post-graduate research scholar with the Singapore Nuclear Science and Safety Initiative (SNRSI).

Kojun Suzuki

Kojun Suzuki, Ph.D., is an independent researcher at Michinoku Fauna Research, Hirosaki, Aomori, Japan.

Hirofumi Tazoe

Hirofumi Tazoe, Ph.D., is an associate professor at Department of International Cooperation and Collaborative Research, Hirosaki University Institute of Radiation Emergency Medicine.

Masatoshi Yamada

Masatoshi Yamada, Ph.D., is a researcher at Central Laboratory, Marine Ecology Research Institute, Japan.

Mitsuaki A. Yoshida

Mitsuaki A. Yoshida, Ph.D., is a professor at Department of Radiation Biology Hirosaki University Institute of Radiation Emergency Medicine.

Tomisato Miura

Tomisato Miura, Ph.D., is a professor at Department of Risk Analysis and Biodosimetry, Hirosaki University Institute of Radiation Emergency Medicine.