Figure 1.
hmp-1(
fe4);
unc-94(RNAi) Embryos Arrest during Embryonic Elongation, and Epidermal UNC-94 Localization to Junctions Requires
hmp-1 Function (A) Nomarski images of representative embryos undergoing elongation are shown at the indicated time intervals. Embryos are initially oriented with the anterior to the left and the ventral side up at time (T) = 0 hr, and lateral views are shown for all other time points. T = 0 hr shows embryos at the completion of enclosure. Wildtype (WT),
unc-94(RNAi),
hmp-1(
fe4), and hmp- 1
(fe4);
unc-94(RNAi) embryos are shown. No obvious defects in elongation are evident in the
unc-94(RNAi) embryo.
hmp-1(
fe4) embryos develop mild body-shape defects during elongation. 95% of
hmp-1(
fe4);
unc-94(RNAi) embryos (n = 93) elongate to the 1.5-fold stage or less, then retract to their original length. See Movie S1. (B) Wild-type embryo expressing JAC-1::GFP to mark AJs and stained with an affinity-purified rabbit UNC-94 antibody. Seam-ventral (*) and seam-dorsal (**) cell borders are indicated. UNC-94 is first detected at epidermal-cell borders around the 2-fold stage of elongation. The color merge shows JAC-1::GFP in green and UNC-94 in red. Enlargement of the boxed region shows UNC-94 staining overlapping JAC-1::GFP. (C) Wild-type stained with phalloidin. CFBs and the junctional-actin belt are indicated. (D) UNC-94 staining in wild-type and
hmp-1 mutants. In wild-type elongation-stage embryos, 23% have UNC-94 localization at epidermal-cell borders (n = 79). In
hmp-1(
zu278) embryos, 0% have UNC-94 localization at epidermal-cell borders (n = 87). In
hmp-1(
fe4) embryos, 35% have UNC-94 localization at epidermal-cell borders (n = 63). Note that this staining was done via freeze-cracking, which is known to disrupt actin but preserves the UNC-94 epitope recognized by UNC-94 antibodies. Disruption of junctional actin caused by this technique may account for the percentage of embryos exhibiting UNC-94 localization at epidermal-cell borders. Bars represent 10 um.