Reactivation by Manganous Chloride of Spores Inactivated by Nitrogen Mustard.

enon, photoreactivation, was later observed in several other organisms such as bacteriophages (DULBECCO 1950), bacteria and fungi of the genera Penicillium and Neurospora ( KELNER 1952). Reactivation of cells inactivated by ultraviolet irradiation was also obtained by means of pyruvic acid and other acids of the Krebs cycle (THOMPSON, MEFFERD and WYSS 1951; HEINMETS et al. 1954). Up to the end of 1957, to the present authors’ knowledge, no case had come to light of the reactivation of cells inactivated by chemical mutagens. At that time it was observed, again by chance (SERMONTI and MORPURGO 1958). that manganous chloride brought about reactivation in conidia of Penicillium chrysogenum inactivated by nitrogen mustard (HN-2). Some of the first results concerning this effect, chemoreactivation, are described at length in this paper. THE by ultraviolet irradiation was first observed by KELNER (1949). The phenom-