Epidermal elongation defines the shape and form of the worm. Elongation involves reciprocal interactions between body muscles and epidermal cells. Genetic analysis of elongation has shown that intermediate filaments are required for this process (Woo et al., 2004). The intermediate filament mutations affecting elongation also show muscle detachment phenotypes. Intermediate filaments are a main component of the trans-epidermal attachment structures that are necessary for epidermal morphogenesis and muscle attachment. Mutations in several genes, including
vab-19,
vab-10A/Plectin, and
eps-8 (Ding et al, East Asia Worm Meeting 2004) cause both epidermal elongation arrest and muscle detachment. These genes either directly or indirectly affect epidermal attachment structures. We have performed clonal genetic screens for epidermal morphogenesis mutants, focusing on those that display aberrant epidermal morphology and arrest at about the two-fold stage. This phenotype corresponds to the 'weak Pat' phenotype described by Barstead and Waterston(1991). In addition to known pat genes we recovered mutations in several genes not previously shown to be involved in elongation including
vab-13/F-spondin (see abstract by Woo et al., this meeting). A second gene identified in this screen is defined by at least six mutant alleles, including the reference semi-lethal allele
ju432, making it the largest target in our screen. The
ju432 phenotype is incompletely penetrant and displays embryonic and larval lethality and muscle detachment. Surviving
ju432 adults show phenotypes varying from extremely bent heads to mild notched heads to wild type. Most mutants also have constrictions along the body and are egg laying defective. We have mapped
ju432 to the center of the X chromosome between the SNPs T21E8.1 and CE6-179, defining an interval of 207kb. No genes in this interval have been previously implicated in epidermal morphogenesis either by mutation or RNAi, suggesting that
ju432 may define a new gene. We will present our continuing efforts to identify the
ju432 locus.