16 August 2002
Vol 297, Issue 5584

About The Cover

Cover image expansion

COVER Bacterial cells simultaneously expressing two different fluorescent proteins (red and green) from identical promoters. Because of stochasticity ("noise") in the process of gene expression, even two nearly identical genes often produce unequal amounts of protein. The resulting color variation shows how noise fundamentally limits the accuracy of gene regulation. 1183 [Image: M. B. Elowitz]