Howard Hughes Medical Institute, Departments of Anatomy and of Biochemistry and Biophysics, The University of California, San Francisco, CA 94143, USA. cori@itsa.ucsf.edu
Two recent chromosome-wide screens for phenotypes caused by RNA-mediated interference (RNAi) in Caenorhabditis elegans have increased our understanding of essential genes in nematodes. These papers represent a major advance in functional genomics.