Main Content

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 3792

Jacqueline A. Osborne and Donard Lee; Studies on the Conditions Required for Optimum Recovery of Tetrahymena pyriformis Strain S (Phenoset A) after Freezing to and Thawing from -196 degrees C. J.Protozool. 22(2):233-237, 1975

Reprint

In File

Notes

The toxicity of several cryoprotective agents was tested at room temperature (23 degrees C) against Tetrahymena pyriformis strain S (Phenoset A) at different stages of the growth cycle. Polyvinylpyrrolidone (PVP-40) at 10% (v/v) concentration was without effect at any stage in the growth cycle, while 1.2 M glycerol immobilized the cells which were disrupted very shortly afterwords. The toxicity of 0.25 M glucose was largely independent of the position of the cells in the growth cycle, but the toxicity of 0.25 M sucrose and 1.4 M dimethylsulfoxide (DMSO) was most marked in late log- and stationary-phase cells. After log-phase cells had been equilibrated with 1.4 M DMSO for 1 hr, the number of cells surviving cooling at defined rates from 0.45 to 12 degrees C/min decreased as the final temperature decreased from -30 to -60 degrees C. A temperature of -53 degrees C was found to be the optimum from which cells cooled at a given rate could be cooled rapidly to -196 degrees C. Nevertheless, when cells were cooled at defined rates to -35, -45, or -53 degrees C and then rapidly to -196 degrees C the optimum rate of cooling to these temperature was found to be 1 degrees C/min. The optimum rate of cooling to -60 degrees C prior to plunging into liquid nitrogen was found to be 2.7 degrees C/min.