Effect of hypothermia (20–25°C) on mitosis in PtK 1 cells

Abstract

PtK 1 cells enter prophase and complete mitosis at 24–25°C but are inhibited from entering prophase at 20–21°C. Cells which have progressed up to midprophase at 24–37°C return to interphase when cooled to 20–21°C, but those in late prophase complete a normal, although prolonged mitosis. If prophase cells which have reverted to interphase at 20–21°C are incubated at 24–37°C they reenter prophase and complete mitosis. This temperature-induced prophase-interphase-prophase transition can be repeated several times on the same cell. At 24–25°C the process of spindle formation (i.e. prometaphase to the initiation of anaphase) encompasses approximately 75% of the total mitotic interval, with a duration of 8–12 h, compared to about 50% of the mitotic interval and a duration of 0.5 to 1.0 h at 37°C.