“…In 1962, Menningmann and Szybalski suggested that the molecular mechanism of thymineless death, simulated by 5-fluorodeoxyuridine treatment, could be correlated to structural changes in deoxyribonucleic acid (DNA) (16). Indeed, single-strand breaks are observed in most Escherichia coli strains undergoing thymineless death (7,18,20,25), although some strains exhibit no change in sedimentation profiles of DNA when lysates of starved cells are centrifuged in alkaline sucrose gradients after several hours of deprivation (1,19). However, other authors reexamined these latter results and reported single-strand breaks (17).…”