Unequal Fission

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Science  18 Feb 2005:
Vol. 307, Issue 5712, pp. 1015
DOI: 10.1126/science.307.5712.1015d

Despite the apparent symmetry of cell division, the rod-shaped bacterium Escherichia coli does not produce progeny that are identical. Upon division, each daughter cell acquires a pre-existing end (old pole) from its ancestor as well as a newly created end (new pole) where the septum forms. In a present-day reenactment of the heroic lineage mapping of the nematode, Stewart et al.followed individual bacteria for nine generations of growth and reproduction; computerized analysis of about 35,000 cells revealed that the cell that inherited the parent's older pole grew more slowly than the cell bequeathed the younger pole. Cells with older poles produced less biomass (summed across their offspring) and had an increased probability of death. Because these asymmetric characteristics are hallmarks of cellular aging in multicellular organisms and in yeast, the study suggests that asymmetric cell division and fundamental mechanisms of aging may be evolutionarily conserved in bacteria. — LDC

PLoS Biol. 3, e45 (2005).

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