Abstract
For the establishment of successful cryopreservation of C. elegans, the response of the nematode to low-temperature stress was investigated in the L4 stage of the life cycle. Pumping for feeding indicated by pharynx was observed under a cryomicroscope, and its frequency was used as an indicator of mobility. Pumping frequency decreased with lowering temperature to stop below 2℃, and it showed thermal hysteresis with higher mobility in the cooling process than the heating process. When kept at 5℃ for cold acclimation, mobility at low temperatures more or less recovered with the time of preservation. However, optimum recovery was indicated at ca. 10 days, and mobility lowered with the further preservation time. On parallel with the increase in the mobility, accumulation of trehalose was indicated during cold acclimation.
