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faculty: "FNWI" and publication year: "2005"
| Authors | S.P. Elmore, M. Muller, N.O.E. Vischer, T. Odijk, C.L. Woldringh | | Title | Single-particle tracking of oriC-GFP fluorescent spots during chromosome segregation in Escherichia coli. |
| Journal | Journal of Structural Biology |
| Volume | 151 |
| Year | 2005 |
| Pages | 275-287 |
| ISSN | 10478477 |
| Faculty | Faculty of Science |
| Institute/dept. | FNWI: Swammerdam Institute for Life Sciences (SILS) |
| Keywords | DNA segregation; Escherichia cloi; Mean square displacement; Random and cinfined diffusion; Simulations |
| Classification | 35.73 biochemistry: molecular genetics |
| Abstract | DNA regions close to the origin of replication were visualized by the green fluorescent protein (GFP)-Lac repressor/lac operator system. The number of oriC-GFP fluorescent spots per cell and per nucleoid in batch-cultured cells corresponded to the theoretical DNA replication pattern. A similar pattern was observed in cells growing on microscope slides used for time-lapse experiments. The trajectories of 124 oriC-GFP spots were monitored by time-lapse microscopy of 31 cells at time intervals of 1, 2, and 3 min. Spot positions were determined along the short and long axis of cells. The lengthwise movement of spots was corrected for cell elongation. The step sizes of the spots showed a Gaussian distribution with a standard deviation of 110 nm. Plots of the mean square displacement versus time indicated a free diffusion regime for spot movement along the long axis of the cell, with a diffusion coefficient of 4.3 ? 2.6 ? 10?5 ?m2/s. Spot movement along the short axis showed confinement in a region of the diameter of the nucleoid (800 nm) with an effective diffusion coefficient of 2.9 ? 1.7 ? 10?5 ?m2/s. Confidence levels for the mean square displacement analysis were obtained from numerical simulations. We conclude from the analysis that within the experimental accuracy ? the limits of which are indicated and discussed ? there is no evidence that spot segregation requires any other mechanism than that of cell (length) growth. |
| Document type | Article |
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