Fig. 5.

Abl∆IDR does not rescue defects in germband retraction or dorsal closure. Embryos stage 13–14, anterior left, dorsal (a–g) or lateral (h–l) views, stained with antibodies to Ecad to visualize cell shapes. a, b Wildtype embryos, dorsal view, at successively later stages of dorsal closure. The embryo is enclosed ventrally and laterally by epidermis but the dorsal surface remains covered by the amnioserosa (AS). The leading edge is straight (blue arrows) and as closure proceeds the epidermis meets and zips at the canthi (red arrows). c Embryo expressing Abl∆IDR in a wildtype background. Dorsal closure proceeded normally. d Representative ablM/Z mutant. Dorsal closure and germband retraction are disrupted. The spiracles remain dorsal (green arrow), the leading edge is wavy rather than straight (blue arrows), zipping at the canthi is slowed or halted (red arrows), and in places the amnioserosa has ripped from the leading edge, exposing underlying tissue (asterisk). e–h. Abl∆IDR; ablM/Z mutants, illustrating the range of defects in dorsal closure. e, f More typical Abl∆IDR; ablM/Z mutants, with a very wavy leading edge (blue arrows), slowed zippering at the canthi (red arrows), and ripping of the amnioserosa from the epidermis (asterisk)-22/33 embryos observed were in this category. g Abl∆IDR; ablM/Z mutant where zippering has happened at the posterior canthus but not the anterior one (red arrows). h Relatively mild phenotype, with closure nearly completed However, the leading edge is wavy (blue arrows) and the spiracles are present dorsally, revealing failure to complete germband retraction (5/33 embryos observed resembled these). i–k Most severe class of Abl∆IDR; ablM/Z mutants, in which the epidermis is reduced in extent, very deep and persistent segmental grooves remain (i, j, green arrows) and presumed multinucleate cells are often observed (k yellow arrows)—6/33 embryos observed resembled these. l Abl∆CR1; ablM/Z mutant for comparison. Scale bar = 15 µm