The array of genes that are expressed during the life cycle of a cell can be pictured as a complex genetic circuit. Laub et al. provide a global survey of the part of that circuit expressed during the cell cycle of Caulobacter crescentus , a bacterium that differentiates during the course of its life. Out of nearly 3000 genes, 553 show cell-cycle regulation. Temporal controls over genes involved in specific cell functions and coordinate regulation of proteins that are part of complexes were also observed. CtRA was shown to be a central regulator of the cell cycle in experiments with overexpressing or loss-of-function mutants. A histidine kinase and two RNA polymerase sigma factors were identified as possible regulators of early S phase. Laub, M.T., McAdams, H.H., Feldblyum, T., Fraser, C.M., and Shapiro, L. (2000) Global analysis of the genetic network controlling a bacterial cell cycle. Science 290 : 2144-2148. [Abstract] [Full Text]