Some Properties of the Deoxyribonucleic Acid of Phage Alpha

Abstract

WE wish to report some results concerning the unique properties of the deoxyribonucleic acid (DNA) isolated from the phage α grown on its host, Bacillus megatherium, strain Paris. This phage and its host have been studied by Drs. S. Aurisicchio, A. Celano, A. Coppo, P. Donini and F. Graziosi, and kindly supplied to us by them. These workers had found that the decay of phosphorus-32 incorporated in the DNA of the phage led to a time-dependent loss of viability similar to that of the phage ϕX-174 (Graziosi,, F., personal communication). Since the DNA of the latter phage has been shown to be single-stranded¹, the DNA of phage α was expected to display similar properties. However, as will be indicated later, many of its properties resemble those of double-stranded DNA with the notable exception that, on denaturation, there are formed two denatured units with distinct buoyant densities in a cæsium chloride gradient.