TY - GEN A1 - Saito, Ryota A1 - Koizumi, Ryota A1 - Sakai, Tatsuya A1 - Shimizu, Taiga A1 - Ono, Taiki A1 - Wanner, Manfred A1 - Takyu, Toshio A1 - Tanaka, Toshihiko A1 - Sogame, Yoichiro T1 - Recovery of proliferative capability in gamma irradiated Colpoda cucullus (ciliated protist) resting cysts and its radiation hormesis T2 - Protistology N2 - The resting cyst is one of the quietest life stages (i.e. cryptobiosis) with hardly measurable or even ceased metabolic activity. However, are the resting cysts just resting? Here, to our knowledge, we report for the first time radiation hormesis in resting cysts. In the present study, we focused on the proliferative capability of excysted cells from 500–4000 Gy-gamma-irradiated Colpoda cucullus resting cysts by a bioassay method. Generally, excysted cells from irradiated cysts lose their proliferative capability. However, we observed an increased proliferative capability promoted by low doses of irradiation. Cells, which had excysted from 500-Gy-irradiated cysts, restored their proliferation capability with a recovery period of 12 h and 24 h before excysting. Additionally, cells, which had excysted from 500-4000-Gy irradiated cysts, recovered proliferative capability by re-forming resting cysts. Here, the proliferative capability of excysted cells from 500-Gy-irradiated cysts was even higher than that of non-irradiated. KW - cyst KW - cell proliferation KW - hormesis KW - stress repair KW - recover Y1 - 2020 U6 - https://doi.org/10.4467/16890027AP.19.006.10837 SN - 1680-0826 VL - 14 IS - 3 SP - 160 EP - 171 ER -