Figure 7.—
bitesize overexpression reveals a potential role for bitesize in salivary gland morphogenesis. (A) Scheme of the bitesize (btsz) locus indicating the gene structure and the position and orientation of the EP identified in the screen. (B–C′) Potential knockdown of Bitesize through overexpression of antisense RNA using EP(3)3567 leads to epithelial defects in the overexpressing cells (arrow in B′) and glands that invaginate with aberrant morphology. (B and B′) A surface confocal stack of a stage 13 embryo. (C and C′) The corresponding internal stack that reveals the glands. Note the absence of Crumbs labeling in the area that shows GFP-EFGas2 marker expression (arrow in B′). GFP-EFGas2 is green in B and C, Crumbs is red in B and C and a single channel in B′ and C′. (D–E′) Ventral views of btszK13-4 mutant vs. wild-type embryos at stage 13. The arrow in D points to the disrupted epidermis in the mutant embryo. Note the disorganization of the placode area compared to wild type (indicated by the brackets in D and E) and the failure to accumulate Shot apically (arrow in E″ indicates the accumulation in the wild type). Crumbs is red in D and E and a single channel in D′ and E′. Shot is green in D and E and a single channel in D″ and E″. (F–I″) Examples of lateral views of btszK13-4 mutant vs. wild-type embryos at stage 14. (F–F″) Highly disrupted and disorganized epidermis in the btszK13-4 mutant (arrows in F point to areas lacking apical circumferential Crumbs labeling; compare to the wild-type epidermis in I–I″). (G–G″) An internal stack of the same embryo as in F (the corresponding internal stack for the wild-type embryo in I is shown in K–K″). Note that the salivary gland of the btszK13-4 mutant embryo is losing apical Crumbs accumulation (G′) compared to the wild type (K′); the phalloidin labeling in G″ still shows cell outlines, but these also lack apical actin accumulation as seen in the wild type (K″). Crumbs labeling is green in F, G, I, and K and a single channel in F′, G′, I′, and K′, and phalloidin is red in F, G, I, and K and a single channel in F″, G″, I″, and K″. (H and L) Confocal stacks of the embryos in F and I at the level where the salivary duct reaches the epidermis labeled for Crumbs. (H) The btszK13-4 mutant. (L) The wild type. Note that the duct in H has lost apical Crumbs accumulation (the arrow points to the remnants of Crumbs labeling in the duct) and that the epidermis at the point from which the glands invaginated is disrupted and lacks apical Crumbs (indicated by the bar in H). (M–N″) The btszJ5-2 mutant at stage 14 also shows disrupted epidermis and loss of Crumbs (M″) and also DE-Cadherin (M′) in the area where the placode was previously located. Crumbs labeling in the invaginated gland is aberrant (N″) whereas DE-Cadherin still appears to be apical (N′). (M–M″) A projection of a 5-μm-thick confocal surface stack. (N–N″) The projection of a 20-μm-thick internal stack covering the whole gland. DE-Cadherin is green in M and N and a single channel in M′ and N′, and Crumbs is red in M and N and a single channel in M″ and N″.