Evaluation of sperm fertilization capacity of large Japanese field mice (Apodemus speciosus) exposed to chronic low dose-rate radiation after the Fukushima accident
Kazu Nihei Syun Tokita Hideaki Yamashiro Goh Swee Ting Valerie Ryo Nakayama Yohei Fujishima Yasushi Kino Yoshinaka Shimizu Hisashi Shinoda Kentaro Ariyoshi
Kazu Nihei
Syun Tokita
Hideaki Yamashiro
Ryo Nakayama
Yohei Fujishima
Yasushi Kino
Yoshinaka Shimizu
Hisashi Shinoda
Kentaro Ariyoshi
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Alternative Title
Abstract
Due to the risk of bias in early developmental processes of radio-sensitive germ cells, the effects of radiation on reproductive ability remain unclear. In this study, wild large Japanese field mice (Apodemus speciosus) within the ex-evacuation zone of the Fukushima Daiichi Nuclear Power Plant (FDNPP) exposed to chronic low dose-rate (LDR) radiation since 2011 were examined. We analyzed the in vitro fertilization (IVF) capacity of cryopreserved A. speciosus sperm from 2012 to 2021 using interspecific zona pellucida (ZP)-free and homogenous wild mice oocytes. The radioactivity concentrations of 134Cs and 137Cs were 3,460–37,630 Bq/kg in the Fukushima wild mice. Frozen-thawed sperm showed generally normal acrosomal and nuclear morphology. No significant differences in sperm penetration rate to that of ZP-free mouse oocytes were observed between the control and Fukushima sperm. When frozen-thawed A. speciosus sperm was used for IVF, 44%–90% homogenous wild mice oocytes fertilized and developed a 2-cell embryo. This study was the first to reveal that long-term chronic LDR radiation exposure (0.18–0.59 mGy/d) associated with the FDNPP accident showed no detrimental effect on the IVF capacity of cryopreserved sperm in wild A. speciosus. This study also provides an alternative framework to estimate radiation effects on wild mice reproduction.
Keywords
Cryopreserved sperm, Fertility, Fukushima accident, LDR radiation, Wild mice
Source Title
Journal of Radiation Research and Applied Sciences
Publisher
Elsevier
Series/Report No.
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Rights
Attribution 4.0 International
Date
2022-09
DOI
10.1016/j.jrras.2022.07.001
Type
Article