Figure 2.

oig-4 encodes a single immunoglobulin (Ig)-domain protein expressed predominantly in body-wall muscle. (A) Structure of the oig-4 genomic locus. Grey line: 5′ untranslated region, SA: splice acceptor site, black box: coding regions, vertical black lines: point mutations, grey box: deletion. kr39 is a missense mutation, kr193 is a change of the fifth base pair of the first intron of oig-4, the tm3753 is a deletion of 239 base pairs. (B) OIG-4 is predicted to be a secreted protein. It contains a signal peptide (sp) and one immunoglobulin domain (Ig). The mutation in the kr39 mutant allele (vertical line) causes a glycine to arginine amino-acid change (G84R). (C) An oig-4 genomic fragment or an oig-4 cDNA expressed by muscle can rescue the oig-4 mutant phenotype. Graphs represent the percentage of dead animals after overnight exposure to levamisole 0.6 mM (mean±s.e.m., n=3 independent experiments of 3–5 independent lines, total number of animals tested: 187–300). (D) oig-4 is expressed predominantly in body-wall muscles (BWM). An artificial operon containing the gfp sequence under the control of an oig-4 genomic fragment drives GFP expression in BWM (arrows). Arrowheads indicate two processes emanating from a pair of head neurons. Non-specific fluorescence is due to the autofluorescence of the intestine (asterisk). Scale bar=10 μm.