Fig. 4.

Abl∆IDR does not effectively rescue defects in cellularization or mesoderm invagination. Embryos, genotypes indicated, anterior left. a–d Cellularization, Phalloidin stained to reveal f-actin except B, is which Armadillo is visualized to reveal cell outlines. a Wildtype. Cellularization was completed normally, producing solely mononucleate cells. b Embryo expressing Abl∆IDR in a wildtype background. No presumed multinucleate cells are observed. c ablM/Z mutant. Defects in actin regulation during syncytial development and cellularization led to the formation of presumed multinucleate cells (red arrows). d Abl∆IDR; ablM/Z mutant. Abl∆IDR fails to rescue the defect in cellularization, and thus multiple presumed multinucleate cells are observed. e, f Stage 9 embryos, stained with antibodies to Ecad or Armadillo to visualize cell shapes. e In wildtype mesoderm invagination is completed normally leaving a straight and even midline (blue arrows). f Embryo expressing Abl∆IDR in a wildtype background. No defects in mesodermal invagination are apparent. g ablM/Z mutant. Defects in mesoderm invagination leave the ventral midline wavy and uneven (blue arrows). Also note the continued presence of presumed multinucleate cells (red arrows). h Abl∆IDR; ablM/Z mutant. Abl∆IDR fails to fully rescue the defect in mesoderm invagination, leaving a wavy midline (blue arrows). Multinucleate cells remain (red arrows). i Abl∆CRI; ablM/Z mutant. The mesoderm invagination phenotype is fully rescued. Scale bar = 15 µm