Feulgen cytophotometry of pine nuclei. II. Effect of pectinase used in cell separation.

Pectinase used for cell separation prior to cytophotometry contains a DNase that is able to penetrate the cells of pine root tips and attack nuclear DNA. When pine root tips were exposed to 1% pectinase (pH 6.0), there was a decrease in nuclear DNA content at every sample point and a sharp drop between 16 and 20 hr. The effect of the DNase was eliminated by preparing the enzyme solution in 0.01 M sodium citrate or 0.001 M EDTA. It is suggested that heat denaturation of the DNase should also be effective and might be used in combination with the magnesium chelators.