When a colony of soil bacteria is exposed to elevated levels of ultraviolet
light (UV), a mass migration begins. In this series of images, the colony
flees the central area and forms a ring around the edge. Initially,
there seems little benefit to the journey because the UV intensity is
equally strong at the center and edge of the colony. A new model, however,
suggests that the UV radiation makes bacteria more sensitive to slightly
higher accumulations of waste in the populated center, and that bacteria
near the colony edges emit chemical attractants to lure their kin to
pristine feeding grounds.
Reported by: A.
M. Delprato, A. Samadani, A. Kudrolli, and L.S. Tsimring, Physical
Review Letters, 8 October 2001
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