Temperature and the progression of HeLa S-3 cells from G2 into mitosis in the presence and absence of the amino acid analogue, para-fluorophenylalanine.

HeLa cells grown in suspension at 37.5 degrees C show an immediate reduction in the rate of progression from G2 into mitosis at suboptimal temperatures. The rate of progression becomes slower the longer the cells reside at the lower temperatures. Shifting cells back to 37.5 degrees C from 33.5 degrees C results in an immediate increase in the flow of cells from G2 into mitosis but not to the optimal (37.5 degrees C) rate of traverse found in unshifted controls. The longer cells reside at 33.5 degrees C before being shifted to 37.5 degrees C, the slower the rate of G2 traverse. G2 cells allowed to incorporate p-fluorophenylalanine (in the absence of phenylalanine) are inhibited from entering mitosis at 37.5 and 39.5 degrees C, partially inhibited at 33.5 and 35.5 degrees C, but remain uninhibited at 32 degrees C. Greater incorporation of 3H-p-fluorophenylalanine and of 3H-leucine in the presence of 0.2 mM p-fluorophenylalanine seen at the lower temperatures than at 37.5 and 39.5 degrees C. Although protein synthetic rates and progression of cells to mitosis at different temperatures show a close correlation, they do not appear to be casually related.