Speaker:  Professor Howard C. Berg, Harvard University

Title:   E. coli in Motion

Abstract:  Flagellated bacteria swim by rotating long, thin, helical filaments that arise at different points on the cell surface. Each filament is driven at its base by a rotary motor only 45 nm in diameter made from about 20 different kinds of parts. Motors powered by protons spin in either direction at speeds up to 300 Hz; motors powered by sodium ions spin much faster. Control of the direction of rotation is the basis for the chemotactic response, i.e., for the ability of cells to swim up spatial gradients of chemical attractants. I will review the history of this subject, describe some of the physics that bacteria know, and tell you about the signal transduction pathway that links chemoreceptors to flagella.

Further Information: http://www.rowland.harvard.edu/labs/bacteria/index.html

Figure Caption: The photograph shows cells of the bacterium Escherichia coli labeled with a green fluorescent dye and photographed with a fluorescence microscope. The cell bodies are about 1 micrometer in diameter by about 2 micrometers long. The predominant flagellar wavelength is about 2.2 micrometers long. In brief: fluorescent E. coli.

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