Summary: Salmonella typhimurium strain 4 a is temperature-sensitive. It grows normally at 25° but stops dividing immediately when shifted to 42°. After the shift cell mass increases at a normal rate and DNA synthesis is unaffected. Viable count remains constant for about 3 h. and then falls off sharply. The filaments formed at 42° divide when returned to 25° after a delay which in broth is about 70 min. This delay is not markedly dependent on the time previously spent at 42° but is mediumdependent, being shorter in enriched media. Eventually all the divisions prevented at 42° take place at 25°. Chloramphenicol almost completely stops filament septation and division, and when added early in the recovery period causes fragility, some lysis and a sharp fall in viable count. Nalidixic acid does not stop filament division. It is concluded that a shift to 42° influences cell division directly by causing the irreversible inactivation of a component required at a late stage of division. The length of the division recovery period when filaments are returned to 25° suggests that the component must accumulate throughout most of the division cycle before division can restart.
AdelbergE. A.,
MandelM.,
ChenG.1965; Optimal conditions for mutagenesis by N-methyl-N’-nitro-N-nitrosoguanidine in Escherichia colik12. Biochemical and Biophysical Research Communications 18:788–795
HelmstetterC. E.,
PierucciO.1968; Cell division during inhibition of deoxyribonucleic acid synthesis in Escherichia coli
. Journal of Bacteriology 95:1627–1633
HirotaY.,
JacobF.,
RyterA.,
ButtinG.,
NakaiT.1968; On the process of cellular division in bacteria. I. Asymmetrical cellular division and DNA-less bacteria in Escherichia coli
. Journal of Molecular Biology 35:175–192
HirotaY.,
MordohJ.,
JacobF.1970; On the process of cellular division in Escherichia coli. III. Thermosensitive mutants of Escherichia coli altered in the process of DNA initiation. Journal of Molecular Biology 53:369–387
HirotaY.,
RyterA.,
JacobF.1968; Thermosensitive mutants of E coli affected in the processes of DNA synthesis and cellular division. Cold Spring Harbor Symposia on Quantitative Biology 33:677–693
RicardM.,
HirotaY.1969; Effet des sels sur le processus de division cellulaire d’Escherichia coli
. Compte rendu Hebdomadaire des séances de l’Académie des sciences, Paris 268:1335–1338
SmithH. S.,
PardeeA. B.1970; Accumulation of a protein required for division during the cell cycle of Escherichia coli
. Journal of Bacteriology 101:901–909
SprattB. G.,
RowburyR. J.1971; Cell division in a mutant of Salmonella typhimurium which is temperature-sensitive for DNA synthesis. Journal of General Microbiology 65:305–314