Salmonella “syringe” ready for its close-up Salmonella bacteria
are tiny, but they wreak mighty havoc on human health, causing
serious, sometimes fatal, food poisoning. In 1998, Jorge Galán,
Ph.D., D.V.M., the Lucille P. Markey Professor of Microbial
Pathogenesis, threw new light on Salmonella’s virulence when his
research team revealed that the bacteria infects cells by
forming “needle complexes,” syringe-like tubes through which
Salmonella exchanges proteins with its host. Now Galán and his
colleagues have joined forces with the laboratory of Vinzenz M.
Unger, Ph.D., associate professor of molecular biophysics and
biochemistry, to paint a vivid three-dimensional portrait of the
Salmonella syringe using a state-of-the-art technique known as
cryoelectron microscopy. In this method, an electron microscope
scans samples that contain many copies of the object of interest
suspended in an ice-like solid at every possible angle
(background in image at right). Researchers then feed scores of
images of the object see