DEV015529 Supplementary Material

Files in this Data Supplement:

• Supplemental Figure S1 -

  Fig. S1. Mib2 is not required for the segregation of myoblast subtypes. (A) Segregation of muscle progenitors and founders, monitored by staining with antibodies to Kr, Runt and Slou. (a) Lateral views of mib2¹/CyO (upper panels) and mib2¹ (lower panels) embryos. (b) Details of the patterns of expression in the segments indicated by the arrowheads in column a; the left panels correspond to mib2¹/CyO control embryos. (c) A scheme of the Kr-expressing founders. (d) Schematic representations of the muscles labelled by the different markers. (B) FCMs segregation is not affected in mib2¹ embryos, as followed by sns expression. Columns a and b as in A. (C) The correct number of muscle adult precursors labelled by Twi segregates in mib2¹ embryos. DaPs, LaPs and VaP indicate the three dorsal, two lateral and one ventral adult precursors per abdominal segment. All embryos are stage 15 with the exception of those stained with Kr, as its expression declines after stage 13. In all panels, anterior is to the left.

• Supplemental Figure S2 -

  Fig. S2. Rescue of mib2 phenotype by FM-specific Mib2 expression and muscle detachments in mib2 mutants. (A-A′′) Expression of Mib2 exclusively in FMs rescues the mib2 loss-of-function phenotype. UAS-mib2 expression in FMs (duf-GAL4 driver) rescues completely the visceral mesoderm phenotype (see Fig. 3A) and the somatic defects (compare with Fig.3A and S2B). (B) Muscle detachments are concomitant with the onset of muscle contraction in mib2 embryos. Stage 16 mib2¹ embryo stained with phalloidin reveals the presence of thin contact with attachments in ventral muscles that are close to detach (arrows).

• Supplemental Figure S3 -

  Fig. S3. Attenuation of mib2 function by RNAi. (A,B) Injection of dsRNA in the presumptive mesodermal anlage of Mhc-τ-GFP embryos phenocopies the embryonic mib2¹ phenotype. Lateral views of mib2¹; Mhc-τ-GFP (A) and injected Mhc-τ-GFP (B) L1 larvae, showing the late muscle pattern; note the presence of myospheres in both panels (arrowheads). (C) Schematic of the lateral region shown in A and B; muscles that remain attached are indicated in green. (D-D′′) Wing disc of a third instar larva 1151GAL4/UAS-lacZ, double stained with anti-Twi (green) and anti-β-gal (red). Co-expression of both markers indicates that 1151-GAL4 drives expression of UAS lines in the precursors of adult muscles before muscle differentiation. (E) Anti-Mib2 staining of En-GAL4/2xUAS-RNAi-mib2 third instar wing disc showing a strong reduction in the levels of endogenous Mib2 in the posterior compartment. (F,G) Adult nota of 3-day-old wild-type (F) and 1151-GAL4/2xUAS-RNAi-mib2 (G) flies, showing a strong detachment phenotype in G, revealed by the presence of empty spaces or bubbles below the cuticle (arrowheads).