Bacterial genes and cell scaffolding. (Evolution).

While human bodies have skeletons of bones, our cells have a framework made of a filamentous network. The origin of this cytoskeleton has been a mystery to biologists because more-primitive cells, bacteria, seemed to lack anything resembling a cytoskeleton or its component proteins--tubulin and actin. Indeed, some researchers suggest that the cytoskeleton represents a fundamental difference between the cells of bacteria and those of animals, plants, and the other eukaryotes.

Cheryl Jenkins and James T. Staley of the University of Washington in Seattle now report that the bacterium Prosthecobacter dejongeii has two genes that are "incredibly similar" to the eukaryotic genes for tubulin's subunits.

"If they have truly identified the origin of eukaryotic tubulins, then it would be extremely important," says Jeffery Errington of Oxford University in England, who studies a bacterial protein with actinlike properties (SN: 3/31/01, p. 1.98). The bacterium might have picked up tubulin genes from a eukaryote, he cautions.--J.T.