Flagella-assisted Cell Fission in Escherichia coli

Hoffman and Frank1 have recently described what they call “snapping movements” during division of Escherichia coli. The evidence presented consists of “a time-lapse series of four photomicrographs … inadvertently obtained from a microculture of E. coli during the snapping of a cell pair”. The whole snapping sequence appears to have taken about one minute seventeen seconds, and is described as follows: “The sister cell on the right side of the photomicrograph (Fig. 2) exhibits a blurring interpreted as owing to a vibrating motion of the cell with its proximal end acting as a moving pivot. The proximal end of the second cell is slightly blurred from movement as well, indicating cell flexion with the midpoint of the cells as the pivot. The right-hand cell at one point during these movements seems to have paused in the long axis of its sister for an appreciable time, since its photographic image in this position is more fully developed than in any other. Fig. 3, photographed at one minute nine seconds from zero-time, indicates continued back and forth motion which was followed by a sudden large hinge movement of the cell in a counterclockwise direction, and a consequent decrease in the obtuseness of the angle formed with its sister … ”.