Obelus regulates the localization of adherens junction proteins. (A and B) Localization of Par-3 in wild-type (WT) embryos and obe¹/obe² mutants. Par-3 aggregates were observed in 71% of obe¹ (n = 24), 92% of obe¹/obe² (n = 26), and 100% of obe²/Df embryos (n = 12) at stage 7, compared with 4% in wild type (n = 23). (C) Stills from bright-field videos of wild-type and obe¹ mutants 30 min after the onset of elongation (germband, black line) with weak (50% egg length), moderate (30–40% egg length), or strong (<20% egg length) defects. (D) Axis elongation in bright-field videos of wild-type and obe mutant embryos (n = 62–93 embryos per genotype). (E) Axis elongation based on automated cell tracking in embryos expressing Resille:GFP. Elongation was significantly reduced in moderate obe¹ mutants (n = 4 wild type and 3 obe¹ videos; P < 0.006 by unpaired t test [t = 30 min value as the test statistic]). Tissue length along the anterior–posterior axis was normalized to the length at t = 0. The mean ± SEM between embryos is shown. (F and G) β-Catenin (red) and neurotactin (green) in stage 7 wild-type and obe¹/obe² mutant embryos. (H–K) Par-3, E-cadherin, and β-catenin in stage 7 wild-type and obe¹/obe² mutant embryos. The obe¹ embryos were the progeny of obe¹/obe¹ females crossed to obe¹/+ males. The obe¹/obe² and obe²/Df embryos were the progeny of obe¹/obe² and obe²/Df(3R)Exel6174 females, respectively, crossed to obe²/+ males. (A–C and H–K) Anterior left, dorsal up. (F and G) Cross sections, apical up. Bars, 10 µm. See also Fig. S1.