Timing of initiation of chromosome replication in individual Escherichia coli cells.

Skarstad, Kirsten; Boye, Erik; Steen, Harald B.

doi:10.1002/j.1460-2075.1986.tb04415.x

Cited by 361 publications

(424 citation statements)

References 44 publications

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“…6b). In our experiments, initiation of DNA replication in the mother cell before cytokinesis cannot be attributed to multifork replication [26][27][28] because we never observe a new round of DNA replication to initiate until the previous round has finished.…”

Section: Resultsmentioning

confidence: 71%

Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria

et al. 2013

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During the bacterial cell cycle, chromosome replication and cell division must be coordinated with overall cell growth in order to maintain the correct ploidy and cell size. The spatial and temporal coordination of these processes in mycobacteria is not understood. Here we use microfluidics and time-lapse fluorescence microscopy to measure the dynamics of cell growth, division and chromosome replication in single cells of Mycobacterium smegmatis. We find that single-cell growth is size-dependent (large cells grow faster than small cells), which implicates a size-control mechanism in cell-size homoeostasis. Asymmetric division of mother cells gives rise to unequally sized sibling cells that grow at different velocities but show no differential sensitivity to antibiotics. Individual cells are restricted to one round of chromosome replication per cell division cycle, although replication usually initiates in the mother cell before cytokinesis and terminates in the daughter cells after cytokinesis. These studies reveal important differences between cell cycle organization in mycobacteria compared with better-studied model organisms.

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Section: Resultsmentioning

confidence: 71%

Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria

et al. 2013

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“…As such, cells doubling in less than this amount of time must maintain multiple chromosome replication forks at different stages of completion. This means that depending on their location along the genome, some genes in our fastgrowing cells (t D = 40 min) exist with either two or four copies [we ignore the short-lived three-copy state that arises when one replication fork briefly outpaces the other (30)] whereas others exist with either one or two copies (SI Appendix, Fig. S1B and Table S5C).…”

Section: Resultsmentioning

confidence: 99%

“…The corrections for RNAP-and TF-associated noise resulted from the promotion of certain rates-k t and k on , respectively-to random variables and Taylor expanding about their means. Similar analyses can be performed for other potential sources of noise, including variability in t r or t D ; in both cases, however, experiments show that the variance of these parameters is generally much less than 10% of their mean (30), and thus they are not likely to significantly impact measurable mRNA noise.…”

Section: Corrections To the Analytical Model For Regulation As Well mentioning

confidence: 91%

Effects of DNA replication on mRNA noise

Peterson

Cole

Fei

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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There are several sources of fluctuations in gene expression. Here we study the effects of time-dependent DNA replication, itself a tightly controlled process, on noise in mRNA levels. Stochastic simulations of constitutive and regulated gene expression are used to analyze the time-averaged mean and variation in each case. The simulations demonstrate that to capture mRNA distributions correctly, chromosome replication must be realistically modeled. Slow relaxation of mRNA from the low copy number steady state before gene replication to the high steady state after replication is set by the transcript's half-life and contributes significantly to the shape of the mRNA distribution. Consequently both the intrinsic kinetics and the gene location play an important role in accounting for the mRNA average and variance. Exact analytic expressions for moments of the mRNA distributions that depend on the DNA copy number, gene location, cell doubling time, and the rates of transcription and degradation are derived for the case of constitutive expression and subsequently extended to provide approximate corrections for regulated expression and RNA polymerase variability. Comparisons of the simulated models and analytical expressions to experimentally measured mRNA distributions show that they better capture the physics of the system than previous theories. stochastic gene expression | stochastic simulation | analytical solutions | chromosome replication | master equation

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“…In the analysis of chromosome replication in E. coli, drug treatment which inhibits initiation of replication but allows ongoing replication forks to finish is often used to determine the numbers of origins per cell (Skarstad et al, 1986). Rifampicin inhibits the transcription necessary for initiation at oriC, while ongoing forks are allowed to finish.…”

Section: The Origin Of Chrii Fires Much Later Than the Origin Of Chrimentioning

confidence: 99%

Replication patterns and organization of replication forks in Vibrio cholerae

2011

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We have investigated the replication patterns of the two chromosomes of the bacterium Vibrio cholerae grown in four different media. By combining flow cytometry and quantitative real-time PCR with computer simulations, we show that in rich media, V. cholerae cells grow with overlapping replication cycles of both the large chromosome (ChrI) and the small chromosome (ChrII). In Luria-Bertani (LB) medium, initiation occurs at four copies of the ChrI origin and two copies of the ChrII origin. Replication of ChrII was found to occur at the end of the ChrI replication period in all four growth conditions. Novel cell-sorting experiments with marker frequency analysis support these conclusions. Incubation with protein synthesis inhibitors indicated that the potential for initiation of replication of ChrII was present at the same time as that of ChrI, but was actively delayed until much of ChrI was replicated. Investigations of the localization of SeqA bound to new DNA at replication forks indicated that the forks were co-localized in pairs when cells grew without overlapping replication cycles and in higher-order structures during more rapid growth. The increased degree of fork organization during rapid growth may be a means by which correct segregation of daughter molecules is facilitated.

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Timing of initiation of chromosome replication in individual Escherichia coli cells.

Cited by 361 publications

References 44 publications

Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria

Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria

Effects of DNA replication on mRNA noise

Replication patterns and organization of replication forks in Vibrio cholerae

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