Fig. 2. Exon-intron structures of six unc-52 minigenes. Exons are represented by boxes, introns by horizontal lines and splices by angled lines that join exons together. unc-52 exons are filled with black; the position of a nuclear localization signal (NLS) is marked by a white line. The positions of nonsense codons found in unc-52(e669) and unc-52(e444) are marked. Known mec-8-dependent splices of transcripts from the complete unc-52 gene (Lundquist et al., 1996) are shown below the unc-52(+) minigene; an expected mec-8-independent splice form (Rogalski et al., 1995) that includes all of the minigene exons is shown above the unc-52(+) minigene.