2020 年 52 巻 p. 1-6
Paramecium, a ciliated protozoan, moves using thousands of cilia that cover the entire cell body. When Paramecium comes into contact with harmful substances such as ethanol, its cilia spontaneously detach and motility is substantially reduced. In the present study, Paramecium cells were shown, for the first time, to acquire tolerance to toxic ethanol concentrations after pretreatment with lower, non-toxic concentrations. The effect of pretreatment was characterized by counting numbers of non-deciliated cells. Key findings were: (1) pretreated cells retained the acquired tolerance to ethanol for at least 24 h and lost tolerance within 48 h; (2) the effect of pretreatment was attenuated by protein synthesis inhibitors; (3) the effect of pretreatment depended on duration and ethanol concentration; (4) pretreatment conferred cells the tolerance to not only a toxic concentrations of ethanol but also to lethal concentrations; and (5) cells acquired ethanol tolerance during starvation. Ethanol-induced tolerance in Paramecium may be a primitive model for cellular memory function.