Virus DNAIn 1944, DNA was identified as the hereditary agent in a virus, published in a report by O.T. Avery, Colin MacLeod, and Maclyn McCarty. This crucial discovery in molecular genetics - that genetic information is carried in the nucleotide sequence of DNA - arose incidentally while studying pneumococcus to monitor the epidemic spread of pneumonia. Since 1928, when British physician Frederick Griffith had found that extracts of a pathogenic strain of that virus could transform a harmless strain into a pathogenic one, scientists had searched for the "transforming factor." The work by Avery, et al., now identified the transforming molecule as DNA, having ruled out, through extract digestions, RNA, protein, and polysaccharide capsular material.[Ref.: Studies on the chemical nature of the substance inducing transformation of pneumococcal types. Induction of transformation by a deoxyribonucleic acid fraction isolated from pneumococcus type III. Journal of Experimental Medicine. 79:137-158., issue of 1 Feb 1944] |
