Ultra-Violet Motion Picture Studies of Effects of Ribonuclease and Deoxyribonuclease on Living HeLa Cells. ∗

Summary

1) Living HeLa cells were incubated in various concentrations of ribonu-clease and deoxyribonuclease and their ultraviolet absorption characteristics were followed for 6 hours by means of time lapse motion pictures obtained with the ultra-violet flying spot television microscope. 2) No change in ultra-violet absorption images of cells was detectable as long as 2 hours after the time that replicate cultures demonstrated a loss of affinity of cytoplasm for basic dyes and the nuclei were negative with Fuelgen stain. 3) Living HeLa cells react to incubation in ribonuclease by first shrinking slightly and then expanding their cytoplasm markedly. 4) Prolonged incubation of HeLa cells in either enzyme eventually produces collapse and pyknosis of all of the cells in the culture.