Influence of Thymine Starvation on the Integrity of Episomal and Chromosomal Deoxyribonucleic Acids in Escherichia coli CR34 (λ ind ⁻ )

Abstract

The effect of thymine deprivation on the integrity of phage X, sex factor, and chromosomal deoxyribonucleic acid (DNA) in Escherichia coli CR34 (X ind-) was examined by sedimenting cell lysates through alkaline sucrose gradients. Both sex factor and chromosomal DNAs showed evidence of being degraded during the starvation period. In contrast, no loss of closed circular X DNA was observed.

Size and transforming activity of deoxyribonucleic acid in Diplococcus pneumoniae during thymidine starvation

“…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).…”