ゾウリムシの凍結保存技術の実用化.

The ciliate Paramecium species are giant eukaryotic cells of 100-250 μm in length and have been used in various researches as model organisms. Successful cryopreservation with DMSO (dimethyl sulfoxide) had been reported. However, due to unstable and low survival rate after the thawing, these methods could not be put into practical use in long-term preservation programs for large numbers of strains. Therefore, majority of Paramecium researchers have prevented senescence by culturing paramecia at low temperatures (about 10℃) to suppress the rate of the cell division, because the lifespan of Paramecium is determined by the number of the cell divisions after fertilization. However, even with this method, clonal death due to aging cannot be avoided. In our research, conventional cryopreservation methods using DMSO have been improved and are beginning to be put to practical use. This improved method consistently resulted in higher post-thaw survival than other previous methods. This method currently yielded viable cells after thawing in P. caudatum, P. bursaria, and P. woodruffi, and further improvements are expected to increase the number of species that can be cryopreserved. [ABSTRACT FROM AUTHOR]