Meselson recounts how the 1958 Meselson-Stahl experiment proved semiconservative DNA replication

Matthew Meselson tells the story, in an iBiology interview, of the 1958 experiment with Franklin Stahl that settled how DNA replicates. After Watson and Crick's 1953 double helix left the mechanism open, three hypotheses competed: conservative, dispersive and semiconservative. Using N15 isotope labeling and density gradient centrifugation in bacteria, the pair tracked heavy, light and hybrid DNA bands across generations, and only the semiconservative model fit.