Fig. 1. vab-19 mutants are defective in embryonic morphogenesis and muscle attachment. (A-H) Frames from time-lapse Nomarski movies of wild-type and vab-19(ju406) embryos. vab-19 mutant embryos appear normal at comma stage and twofold stage (E,F). 70 minutes after the twofold stage, the wild-type embryo has elongated to the threefold stage (C), whereas the vab-19 mutants have stopped elongation and show constrictions and lumps in the epidermis (G). vab-19 mutants typically hatch as deformed L1 stage animals with extensive muscle detachment (H, arrowhead; I,J, arrow). (K-N) Epidermal junctions visualized by AJM-1::GFP in wild-type and vab-19 embryos at 1.75-fold (K,M) and post-twofold stages (L,N), showing that epidermal adherens junctions form normally in vab-19 mutants. (O) The vab-19(e1036cs) temperature-sensitive period (TSP) is during early elongation. The x axis represents developmental stages at which embryos were up- or down-shifted. The y axis represents the proportion of embryos that showed vab-19 lethal and Vab phenotypes at 22.5°C. At least 24 embryos were scored for each time point. Up-shift involved transferring embryos raised at 15°C to 22.5°C, whereas down-shift involved transferring embryos raised at 22.5°C to 15°C. The midpoint of the TSP is between the 1.5-fold and twofold stages.

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