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Figure 4 | BMC Developmental Biology

Figure 4

From: Varicose: a MAGUK required for the maturation and function of Drosophila septate junctions

Figure 4

Distribution of septate junction markers and the seal of the transepithelial barrier are compromised in vari mutants. (A-D) Distribution of SJ markers in vari mutants. (A) Balancer LacZ control. (B, C) variGE13049. (D) vari48EP. Homozygous embryos selected by absence of balancer lacZ and visualized by confocal microscopy. FasIII (A), NrxIV, and Na+K+ATPase (q.v. Fig. 2F, G) localize to hindgut epithelial SJs in lacZ control embryos and are excluded basally (arrow, A). In vari mutants, NrxIV, FasIII, and Na+K+ATPase are mislocalized basally along the lateral plasma membrane (arrows B, C, and D, respectively). (E, F) We assessed the distribution of Vari in the SJ mutant, nrg. In control embryos, Vari localizes to the SJ of hindgut epithelial cells (arrow, E), however accumulation of Vari is greatly reduced and mislocalized basally in nrg mutants (arrow, F). All embryos are stage 15. (G, H) The integrity of the transepithelial barrier in vari48EPmutants was determined by permeability assay as described by Lamb et al. (1998). Following injection of rhodamine-conjugated dextran, dye was detected within the tracheal lumen of mutants (arrow, H) but excluded from the lumen in controls (arrow, G), indicating disruption in barrier function. Dye remained undetectable in the lumen of controls 90 minutes post-injection. a, apical. Calibration: 2 μm, A-F; 10 μm, G-H.

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