Fig. 2: Ablation of DNRX causes defects in the muscle structure of Drosophila larvae.

a Upper panel: Muscle pattern diagram of third-instar Drosophila larvae. Scale bar, 200 μm. The dashed white box represents the area shown in (b, c”’). Bottom panel: The enlarged area is outlined in the white box in the upper panel for clarity. Scale bar, 100 μm. The arrangement of muscles in part of a hemisegment in w¹¹¹⁸ files; the muscles referred to in the text are labeled by number according to standard nomenclature. b, c”’ Phalloidin-stained muscles of Drosophila larvae expressing mef2-Gal4 > UAS-mCD8-GFP (Control) and mef2-Gal4 > UAS-mCD8-GFP, dnrx²⁷³. Phalloidin (red) was used to visualize actin, GFP (green) was used to label the cell membrane, and DAPI (blue) was used to label the nucleus. Scale bar, 100 μm. d–f Characterization of larval muscle structure. Average muscle length (d), average muscle width (e), and muscle area (f) of muscle 6 or 7. mef2-Gal4 > UAS-mCD8-GFP (n = 8) and mef2-Gal4 > UAS-mCD8-GFP, dnrx²⁷³ (n = 7). The data are presented as the means ± SEMs. ****p < 0.0001, ***p < 0.001, **p < 0.01, *p < 0.05; two-tailed unpaired Student’s t-test. g Electron micrographs of larval muscle showing the muscle fibers of w¹¹¹⁸ flies and dnrx²⁷³ mutants in transverse sections. Scale bar, 0.2 μm. h Quantification of the number of muscle fibers per unit area in w¹¹¹⁸ flies (n = 15) and dnrx²⁷³ mutants (n = 15). The data are presented as the means ± SEMs. ****p < 0.0001; two-tailed unpaired Student’s t-test. i, j, l Phalloidin-stained muscles of Drosophila larvae showing muscle attachment in the indicated genotypes. The dashed lines represent the boundaries of muscles 6 and 7. The double dashed lines indicate misalignment of muscle attachment in muscles 6 and 7. * indicates muscle loss. Scale bar, 100 μm. k Quantification of the ratio of muscle defects. elav-Gal4 rescue (elav-Gal4 > UAS-dnrx, dnrx²⁷³), mef2-Gal4 rescue (mef2-Gal4 > UAS-dnrx, dnrx²⁷³). The data are presented as the means ± SEMs of three independent experiments. n = 22, 25, 22, 22, 24, 24 for the different genotypes from w¹¹¹⁸ to mef2-Gal4 rescue. **p < 0.01; ns, p > 0.05; one-way ANOVA test. m Quantification of the ratio of muscle defects in Drosophila larvae in which DNRX was knocked down in muscle and in neurons. The data are presented as the means ± SEMs of three independent experiments. n = 24, 22, 24, 23, 21, 24, 20 for the different genotypes from elav-Gal4/+ to UAS-dcr;UAS-dnrx IR/+. ****p < 0.0001, ***p < 0.001; ns, p > 0.05; one-way ANOVA test.