Fig. 3

Homozygous F437I and A234T mutations disrupt myofibril assembly and stability. Each panel is representative of the myofibril population at that given stage of development, although varying levels of degeneration were observed as mutant organisms aged. a Transverse and longitudinal sections from wild-type transgenic control (pwMhc2) late-stage pupae. Rounded myofibril morphology with normal hexagonal packing of thick and thin filaments is observed, along with clearly demarcated M- and Z-lines in well-defined sarcomeres. b Transverse and longitudinal sections from wild-type transgenic control (pwMhc2) 2-h-old adults. Myofibril structure is retained. c Transverse and longitudinal sections from wild-type transgenic control (pwMhc2) 2-day-old adults. Myofibril structure is maintained. d Transverse and longitudinal sections from homozygous F437I late-stage pupae. Myofibril morphology and hexagonal packing of thick and thin filaments are abnormal. Sarcomeres display fraying and disrupted M- and Z-line structure. e Transverse and longitudinal sections from homozygous F437I 2-h-old adults. Continued disruption in hexagonal packing of thick and thin filaments is observed with more severe sarcomere structural aberrations. f Transverse and longitudinal sections from homozygous F437I 2-day-old adults. Breakdown in myofibril morphology with thick and thin filament dispersion has occurred. Sarcomeres show granular inclusions. g Transverse and longitudinal sections from homozygous A234T late-stage pupae. Myofibril morphology and hexagonal packing are poor. Sarcomeres display fraying with abnormal M- and Z-line structures. h Transverse and longitudinal sections from homozygous A234T 2-h-old adults. Disruption in myofibril morphology and hexagonal packing of thick and thin filaments continues. The transverse section displays a complete breakdown of sarcomere organization, with skeins of filaments and scattered Z-band material. i Transverse and longitudinal sections from homozygous A234T 2-day-old adults. Disruption in myofibril morphology is severe with scattered thick and thin filaments along with granular material in both transverse and longitudinal sections. M, M-line. Z, Z-line. Scale bars, 0.5 μm