Fig. 6: Mesoderm-specific functional cooperation of Ubx with BioID interactors.

a Schematic illustration of the muscle patterns in the thoracic segment 3 (T3) and the first two abdominal segments (A1, A2). Lateral transverse (LT) muscles are highlighted in blue, ventral acute (VA) muscles in orange and ventral oblique (VO) muscles in red, corresponding muscles in all the images are marked with asterisks or arrows in the indicated colours. b Quantification of muscle phenotypes in the indicated genotypes. Phenotype–genotype association was done by using LacZ staining driven by the marked balancer chromosomes. Strong and strong/medium phenotypes correspond to double homozygous mutants and mutants homozygous for one allele and heterozygous for the other. Embryos heterozygous for both mutant alleles showed either a mild phenotype or a hardly visible phenotype, categorized as “no phenotype”. c–q Immunostainings of stage 16 embryos of the indicated genetic backgrounds with tropomyosin (Tm1) to visualise the muscle pattern. While single heterozygous mutants (c–g) did not display any obvious muscle phenotype, double heterozygous mutants (h–l) had changed muscle morphology, which was distinct from the single homozygous mutant phenotypes (m–q). A significant loss of the lateral transverse muscles is detectable in Ubx¹,tin³⁴⁶/TM6-Dfd>lacZ (i), Srp54^DG02112/CyO-wg>lacZ;Ubx¹/TM6-Dfd>lacZ (k) and snRNPU1-70K⁰²¹⁰⁷/CyO-wg>lacZ;Ubx¹/TM6-Dfd>lacZ (l) double heterozygous mutants indicated by blue asterisks and an open arrowhead. brm²,Ubx¹/TM6-Dfd>lacZ (j) double heterozygous mutant embryos show an aberrant muscle pattern indicated by the closed blue arrowheads. m Ubx¹ homozygous mutants show a homeotic transformation of A1 and A2 to T3 identity indicated by the missing asterisks (red, orange), while Srp54^DG02112 (p) and snRNPU1-70K⁰²¹⁰⁷ (q) homozygous mutants show discrete muscle phenotype characterized by thinner muscles except tin³⁴⁶ embryos that present a total loss of body wall muscle affecting the general aspect of embryos. Maximum Z-projections of lateral view are presented. Images are representative of 50 embryos analysed per genotype over 3 sets of pooled embryos from independent collection as quantified in b. Scale bar: 50 µm. See also Supplementary Figs. 8–10. Source data are provided as a Source Data file.