SUMMARYInfection of BHK 2I (C 13) or HEp-2 cells with herpes virus was followed by a marked increase in the activity of alkaline DNase which was prevented by actinomycin D and puromycin. Activation of a latent enzyme was not responsible for the increase. The properties of the DNase appearing after virus infection in both cell types were the same, but they differed from those of the enzyme from uninfected cells in specificity towards the secondary structure of the DNA substrate, heat-stability, requirement for thiol groups, inhibition by K + and Na + ions and response to various concentrations of Mg ~+ and Mn ~+. The activities of acid DNase and alkaline phosphomonoesterase were not significantly altered after herpes infection. Further, the activity of alkaline RNase was not altered by infection, and this implies that the induced DNase was specific for DNA. The new DNase could be separated from the DNase present in uninfected cells and from alkaline phosphomonoesterase by chromatography on columns of DEAE-cellulose; its enzymic properties were the same as those observed with soluble extracts of cells infected with herpes virus.

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SHORT COMMUNICATIONS 37c large phosphatidylethanolamine particles are hydrolysed without the necessity for the addition of diethyl ether. This latter solvent probably activates the hydrolysis of lecithin particles by causing a wider spacing of the phospholipid molecules orientated at the lipid-water interface as well as preventing the accumulation of the liberated fatty acids at this interface. The lack of hydrolysis of high-pressure phosphatidylinositol films is not consistent with this idea, but here other factors may be operative. Thus such films have a much higher affinity for 45Ca than either lecithin or phosphatidylethanolamine (Dawson, 1965, and unpublished work), and this may have the effect of masking the stimulating effect of the interfacial anionic groupings.I am indebted to Dr H. B. Stewart of the University of Western Ontario for a culture of Lipomycee lipofer.

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