Chromatography and Nucleotide Sequences of Deoxyribonucleic Acid synthesized in Salmonella typhimurium after Irradiation with Ultra-Violet

IT has been shown 1,2 that ultra-violet irradiation produces in some kinds of bacteria, for example, Escherichia coli B/r and Salmonella typhimurium , a temporary inhibition of deoxyribonucleic acid (DNA) synthesis. The synthesis is resumed after 30–60 min. and proceeds at a rate similar to the control, but the surviving bacteria are growing only in mass, having lost their ability to form colonies. One of the possible explanations for such behaviour is that DNA synthesized after temporary inhibition is different from the normal one. That this might be so is supported by Kanazir et al. 3 , who found that whereas DNA from non-irradiated Sal. typhimurium could reduce the damage to an irradiated culture, that from an irradiated culture could not, and by Hudnik and Glisin 4 , who showed that the thermal denaturation pattern followed by viscosity and ultra-violet absorption measurement was different in the two DNA's.