2018 Fiscal Year Final Research Report

Studies of radiation effects on the Tohoku hynobiid salamander for environmental risk assessment of the Fukushima nuclear accident

Research Project

PDF

Project/Area Number	16K00553
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Risk sciences of radiation and chemicals
Research Institution	National Institutes for Quantum and Radiological Science and Technology
Principal Investigator	Fuma Shoichi 国立研究開発法人量子科学技術研究開発機構, 放射線医学総合研究所福島再生支援本部, チームリーダー (40260236)
Co-Investigator(Kenkyū-buntansha)	宇根ユミ岡山理科大学, 獣医学部, 教授 (40160303) 久保田善久国立研究開発法人量子科学技術研究開発機構, 放射線医学総合研究所福島再生支援本部, 専門業務員 (70161685)
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	両生類 / 被ばく / 防護 / 成長 / 性成熟 / 細胞増殖
Outline of Final Research Achievements	In chronic γ-irradiation experiment, no adverse effects on the Tohoku hynobiid salamander, Hynobius lichenatus, were observed at a dose rate of 33 μGy/h. Sexual maturation was inhibited at 150 μGy/h or higher. Body weight increase was suppressed and mortality was increased due to nephropathy and hepatic necrosis at 510 μGy/h. This suggests that a radiation exposure at the highest dose rate (50 μGy/h) estimated in the exclusion zone of the Fukushima nuclear accident may not adversely affect this salamander. The salamander larvae were exposed to contaminated sediment collected in the exclusion zone. No skin lesions occurred in the juveniles growing from these exposed larvae, unlike the juveniles growing from the larvae collected in the exclusion zone. Positive rates of PCNA (proliferating cell nuclear antigen), a cellular marker for proliferation, were significantly decreased in the hepatocytes and tubular epithelium cells of the irradiated salamanders.
Free Research Field	放射線生物学
Academic Significance and Societal Importance of the Research Achievements	高汚染地域であっても福島県に生息するサンショウウオに放射線の悪影響が生じる可能性は低いことを示したことは学術的および社会的に意義が大きい。また、本研究のように、管理された実験室で長期にわたって低線量率の放射線を動物に照射し続けて、その影響を調べた例はほとんどなく、環境の放射線防護のための国際的指針作成に資するデータとして今後利用されることが期待できる。さらに、低線量率放射線被ばくによって性成熟が阻害されたり、致死的な腎障害が発生する事象はこれまで知られておらず、これらの事象が（有尾）両生類に特異的なのか、それとも動物に共通するものなのかは放射線生物学的に興味深い。