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Shedding Light on Phototaxis

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Science  17 Mar 2000:
Vol. 287, Issue 5460, pp. 1889
DOI: 10.1126/science.287.5460.1889h

Under starvation conditions, the unicellular slime mold Dictyostelium discoideum aggregates into a multicellular mass referred to as a slug. Aggregation occurs as a chemotactic response to periodic cAMP signals initiated at the center of accretion. Although these cAMP waves coordinate chemotaxis, how light produces phototaxis has been unclear. Miura and Siegert demonstrate that light directly induces the release of cAMP from severed slug tips in culture, and that this is followed by migration of single slime mold cells toward the slug tip aggregate. As expected, this chemotactic response was specifically dependent on the presence of cAMP receptors; in addition, light increased the frequency of cAMP waves in Dictyostelium aggregates. Thus, phototaxis and light perception are mediated in the multicellular slug by the anterior tip.—JN

Proc. Natl. Acad. Sci. U.S.A.97, 2111 (2000).

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