Action Spectra for Photoreactivation of Ultraviolet-irradiated Escherichia Coli and Streptomyces Griseus* B~ Albert Kelner~

The lethal effect of ultraviolet light, k 254 m/z, on Esckerichia toll, Streptomyces griseus, and other microorganisms can be largely prevented if following ultraviolet irradiation the cells are exposed to visible and near-ultraviolet light in the vicinity of 400 m~ (Kelner, 1949 a, 1949 b, 1950). Such light-induced recovery (or pkotoreactivation, pkotore~ersal, or pkotorecwoery) has been confirmed in diverse forms, including: several bacteriophages attacking E. coli (Dulbecco, 1949, 1950); Paramecium aurella (Kimball and Gaither, 1950; Kimball, 1950); Amblystoma larvae (Blum and Mathews, 1950); and gametes of the sea urchins Arbacia punctulata (Marshak, 1949; Blum, Loos, and Robinson, 1950) and Strongylocentrotus purpuratus (Wells and Giese, 1950). In the sea urchin material it is the delay in cleavage of the zygote induced by UV 1 irradiation of sperm or egg which is reversed by visible light. Wells and Giese (1950) showed that cleavage delay in Strongylocentrotus due to irradiation with ~ 2450 A was less readily photoreactivated than that due to ), 2537, 2654, 2804, 3025, and 3130 A. In addition to its prevention of injury or death, phenomena which are at least in part physiological, visible light also prevents the genetic or mutagenic action of UV in E. coli (Keiner, 1949 b; Novick and Szilard, 1949; Newcombe, 1950), Paramecium aurelia (Kimball and Gaither, 1950; Kimball, 1950), Neurospora crassa (Goodgal, 1950), and PenidUium ckrysogenura (Roegner, 1950). Since photoreactivation works on many UV effects, it may ultimately clarify the interrelationships between the primary UV-induced change, or changes, in the cell, and the complex genetic and physiological effects resulting therefrom. And since photoreactivation is demonstrable in so many diverse organisms, it is probably a general cellular phenomenon.