Heavy ion beams: An application to mouse mutagenesis

Abstract

Using C57BL/6J (B6) male mice from which the epididymidis was removed, experiments of mouse mutagenesis for heavy ion beam irradiation were conducted. The mice were exposed to heavy ion beams of Ar-40 at 95 MeV/u, Fe-56 at 90 MeV/u, and Ne-20, N-14 and C-12 at 135 MeV/u with dose range of 5, 10, 20, 30, 50, 75 and 100 Gy. After the irradiation, the sperm suspensions were stored at 4 C, and G1-G3 generation mice were produced by artificial manipulation. The external anomalies were found in G1-G3 generation so far. The induction of mutations was also tried on the male meiotic germ cells, and their hypogastric and scrotum regions were exposed to heavy ion beams of Ar-40, Fe-56, Ne-20, N-14 and C-12 with dose ranges of 0.5, 1, 3 and 5 Gy. The testis tissues were severely damaged after the irradiation. The germ cells in seminiferous epitheliums decreased significantly with higher dose of heavy ion beams. Following the sterile periods, some male mice could restart reproduction. In G1, the embryos morphological anomalies were found in different organs and systems.

精巣を切除した雄のC57BL/6J(B6)マウスを使って、重イオン照射によるマウスの突然変異誘発実験を行った。マウスには、95MeV/uのAr-40、90MeV/uのFe-56、ならびに135MeV/uのNe-20、N-14およびC-12の重イオンビームを、5、10、20、30、50、75および100Gyの線量で照射した。照射後、精液の懸濁液を4度Cで保存し、人工的処理を施して、G1-G3世代のマウスを生産した。これまでのところ、G1-G3世代に外部異常が見られている。また、雄の減数分裂性胚芽細胞の突然変異誘発も試み、その胃下部および陰嚢部分をAr-40、Fe-56、Ne-20、N-14ならびに12-C-12の重イオンビームを、0.5、1、3、および5Gyの線量で照射した。照射後の精巣組織は重大な損傷を受けた。精上皮の胚芽細胞は重イオンビーム線量の増大と共に著しく減少した。不妊期終了後、雄のマウスは再生産を行うことが可能となった。G1では、色々な器官および系において、胚の形態異常が見つかった。