Figure 1 Genes used to study RNA-mediated genetic interference in C.elegans. Intron–exon structure for genes used to test RNA-mediated inhibition are shown (grey and filled boxes, exons; open boxes, introns; patterned and striped boxes, 5' and 3' untranslated regions. unc-22. ref. 9, unc-54, ref. 12, fem-1, ref. 14, and hlh-1, ref. 15). Each segment of a gene tested for RNA interference is designated with the name of the gene followed by a single letter (for example, unc22C). These segments are indicated by bars and upper-case letters above and below each gene. Segments derived from genomic DNA are shown above the gene; segments derived from cDNA are shown below the gene. NLS, nuclear-localization sequence; MtLS, mitochondrial localization sequence.