Daughter cell fusion and formation of polykaryons in a cold-resistant (CR) L cell variant.

A cold-resistant (cr) variant of mouse L fibroblasts called LC3, isolated by repeated cooling of the parent population for several weeks at 4 degrees C, differed from the wild-type cells in morphology and function. Microcinematographic records demonstrate that their motility is markedly reduced when compared with that of the L cells. They enter mitosis at 30 degrees C, at 37 degrees C and at 39 degrees C, but they finish cytodieresis only at 30 degrees C. At the higher temperatures, they reach anaphase, but then the daughter cells fuse and form polykaryons. At 39 degrees C, bizarre forms with large undulating membranes predominate in the damaged population. The cr cells may be used as a model for the study of temperature adaptations on cellular level, as well as for the analysis of the relations between membrane properties, cold resistance and cell cycle control.