E. coli ages

The bacterium Escherichia coli, previously considered not susceptible to aging, and thus functionally immortal, does experience aging and death, researchers report in February's PLoS Biology.

"Until recently, people thought that bacteria cannot age," said Martin Ackermann, of the ETH Zentrum, who was not involved in the study. "Then, we published this paper showing aging in bacteria with asymmetric division. The next question was if a visible morphological asymmetry was necessary or whether all bacteria could age. This new paper suggests that aging can actually be found in all bacterial cells, maybe in all living cells."

In the PLoS study, Eric Stewart, of INSERM and Paris 5 René Descartes University, and his colleagues used automated time-lapse microscopy to follow individual bacteria throughout nine subsequent cycles of reproduction and measured several physical parameters in over 35,000 cells. They found that daughter cells that inherited the "old pole" of a dividing parent cell—a ...