PHOTOREACTIVATION OF INDUCED MUTATION AND INACTIVATION OF ESCHERICHIA COLI EXPOSED TO VARIOUS WAVE LENGTHS OF MONOCHROMATIC ULTRAVIOLET RADIATION

Ultraviolet mutagenesis and inducible DNA repair in Escherichia coli.

“…This "fluence-squared" (F2) relation implies that two independent photon absorptions (UV "hits") are required to induce a mutation. The nature of the two "hits" has been a source ofspeculation for nearly two decades (25,33,61,64,148,224,240,249).…”

Ultraviolet Mutagenesis in Bacteriophage T4 II. Photoreversal of Mutational Lesions

“…Similar studies in bacteria have been at least partly frustrated by phenomena such as nonlinear mutation kinetics and strong dependence of PHR upon the original UV dose (19), as well as PHR of mutations in cells lacking the PHR enzyme (see below). A variety of UV-induced mutations are susceptible to PHR in bacterial systems, however (15,18,19,20,25,26).…”