Stochastic nucleoid segregation dynamics as a source of the phenotypic variability in E. coli.

Segregation of the replicating chromosome from a single to two nucleoid bodies is one of the major processes in growing bacterial cells. The segregation dynamics is tuned by intricate interactions with other cellular processes such as growth and division, ensuring flexibility in a changing environment. We hypothesize that the internal stochasticity of the segregation process may be the source of cell-to-cell phenotypic variability, in addition to the well-established gene expression noise and uneven partitioning of low copy number components.

Single Molecule Study of the Polymerization of RecA on dsDNA: The Dynamics of Individual Domains.

In the , RecA plays a central role in the recombination and repair of the DNA. For homologous recombination, RecA binds to ssDNA forming a nucleoprotein filament. The RecA-ssDNA filament searches for a homologous sequence on a dsDNA and, subsequently, RecA mediates strand exchange between the ssDNA and the dsDNA.

A preliminary census of copies of the first edition of Newton's (1687).

When Henry Macomber published his census of owners of the first edition of the in 1953, he believed the edition to be small, 'perhaps not more than 250 copies', an estimate that still enjoys currency. Lower estimates of the size of the first edition of the were based partly on assessments regarding an inhospitable market for highly technical mathematical books, and partly on the presumption that the vaunted incomprehensibility of the would have militated against a sizeable edition. Our preliminary census more than doubles the number of identified copies, to 387-suggesting a much larger print run than commonly assumed - as well as encourages us to believe that there existed a wider, and competent, readership of the from the start.

Optimal trapping stability of Escherichia coli in oscillating optical tweezers.

Single-beam oscillating optical tweezers can be used to trap rod-shaped bacterial cells and align them with their long axis lying within the focal plane. While such configuration is useful for imaging applications, the corresponding imaging resolution is limited by the fluctuations of the trapped cell. We study the fluctuations of four of the coordinates of the trapped cell, two for its center of mass position and two for its angular orientation, showing the way they depend on the trap length and the trapping beam power.

Response to H. Floris Cohen's essay review on Newtonian scholarship.

Long ago, George Sarton set down criteria for reviewers. In addition to insisting on the need to compose 'faithful' reviews, he cautioned against four types of unfit reviewers: the 'egoist', the 'obscure' reviewer, the one who is noncommittal, and the pedantic critic. Unfortunately, Cohen's review comes short on several counts.