Abstract
Cryopreservation of the nematode Caenorhabditis elegans in the adult stage is of importance as the nematode is a powerful model organism. In this study, we applied the protocol previously established for cryopreservation of the L4 nematode to the adult one. Survival rate of 84% was obtained as a result. When ice nucleation active bacteria, Pseudomonas syringae, was used for the simplification of ice seeding procedure instead of the use of a pre-cooled needle, survival rate of 82% was obtained after thawing. Moreover, a simple method of cryopreservation using a deep freezer and polystyrene foam was developed for a practical purpose. According to the observation under a cryomicroscope, eggs in the nematode body were found to freeze at ca. -20℃ when cooled at the rate of 0.2℃/min after ice seeding at -3℃ although the nematode body remained unfrozen down to -100℃.
