Mapping and cloning of unc-18(sy671). (A, B) Summary of the cloning of sy671. (A) Initial SNP mapping placed sy671 on chromosome X between markers ZC449 and F11A1. Three-factor mapping using lon-2 and egl-15 flanking sy671 allowed for isolation of 99 Lon non-Egl recombinants. Numbers between the markers represent the number of recombinants isolated between those markers and the phenotype of those worms when made homozygous. (B) The cosmid clones covering the interval containing sy671 that were transformed in pair-wise combination are shown. F27D9 transformed alone was able to rescue sy671. The five PCR products used to further define the locus are shown, with P5 being able to rescue when transformed into sy671 mutants. (C) The genomic organization of unc-18 (boxes represent exons). Position of the putative start ATG is shown and the genomic region from start to stop is 2.3 kb. The position of the molecular lesions in 13 previously identified alleles, and the change in sy671, are indicated. The numbering is based on C. elegans isoform A (WormBase WS130).