Fig. 6. Misexpression of hbs in the embryonic epidermis disrupts muscle attachment. (A) Wild-type embryonic somatic musculature in three hemisegments. Arrows indicate a segmentally reiterated group of three muscle fibers in the lateral musculature, while arrowheads indicate the external ventral muscles. (B) UAS-hbs/en-GAL4 embryo show occasional failure of the three muscle fibers (shorter arrows) to insert at their dorsal attachment sites. More ventral muscles fibers are also occasionally defective (arrowhead). (C) The ability of the three lateral muscle fibers to insert at their dorsal attachment sites is comprehensively overturned in the UAS-hbs/sca-GAL4 embryo (shorter arrows). Ventral muscles fibers sometimes no longer span the hemisegment correctly (arrowheads). (D) Overexpression of hbs in the dorsal epidermis with the pnr-GAL4 driver results in dorsal muscle fibers failing to extend across the segment (arrows), or sending a thinned process (arrowhead). Many fibers remain aligned with the segment boundary. Preparations are stained with mAb FMM5.
