期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：11
页码：5645-5649
DOI：10.1073/pnas.75.11.5645
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A class of mutants of Paramecium tetraurelia has been isolated by adding a critical amount of K+ to mutagenized, autogamized cultures. Adding 35 mM K+ to the medium kills the wild type. The mutants can grow at 35 mM K+ and some survive an addition of up to 80 mM K+. Thirty-three lines of such mutants have been studied. These mutants have few or no behavioral abnormalities in culture medium. Paramecia can "adapt." Hildebrand and Dryl showed that P. caudatum incubated in 15 mM K+ for over 15 min fail to give avoiding reactions when challenged with Ba2+ or a thermal gradient [Hildebrand, E. & Dryl, S. (1976) Bioelectrochem. Bioenerg. 3, 543-544]. We have observed a similar phenomenon in wild-type P. tetraurelia. However, the K+-resistant mutants show little or no such "adaptation," i.e., they perform avoiding reactions when challenged with Ba2+ after prolonged incubation in 15 mM K+. The K+ resistance and the lack of "adaptation" are strictly correlated. Because all 33 lines of mutants show this correlation, "adaptation" and killing by K+ must share a mechanism. This mechanism may be studied by finding the basis of the K+ resistance in the mutants. The possible ionic bases of "adaptation" are discussed.
