Application of amidic and acetonic cryoprotectants for volvocalean green algae
Atsushi Nakazawa1 and Ichiro Nishii2
1) Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
2) Department of Biological Sciences, Nara Women's University, Nara 630-8506, Japan
Cryopreservation of volvocalean green algae from unicellular Chlamydomonas to multicellular Volvox by two-step cooling method using various cryoprotectants was examined. Together with conventional use of methanol (MeOH), our present study showed that several amidic and acetonic reagents worked as cryoprotectants for these green algal strains. As previously reported, MeOH is effective for Chlamydomonas and small-colonial species but it doesn't work for larger and multicellular volvocalean genera. On the other hand, some amidic and acetonic reagents were effective for larger volvocalean species such as Volvox, Pleodorina, Astrephomene and Platydorina, most of which had never been reported to be succeeded in cryopreservation. In addition, the RFLP analysis of V. carteri wild type genomic DNA probed by a cold-inducible transposon showed no change of any bands after cryopreservation for a month, suggesting the transposon was rather stable at the long-term freezing. Thus, we propose that these applications will reduce the current difficulty of keeping many mutant strains induced by the transposon.
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