Fig. 3.

Muscle morphology in IFMs of Mhc^K1728del mutant adult flies. IFMs were labeled for Mhc and Kettin/Titin (A) or Mhc and Obscurin (B) in 4-d-old, and 2- and 5-wk-old adult flies. Each panel shows control animals (Top), Mhc^K1728del/+ animals (Middle), and Mhc^K1728del/Mhc¹⁰ animals (Bottom) for each age group. Control flies show parallel periodic striations across the IFMs at all ages. Heterozygous Mhc^K1728del/+ and Mhc^K1728del/Mhc¹⁰ animals show progressive disruptions in sarcomeric structure with age. The 4-d-old Mhc^K1728del/Mhc¹⁰ flies show distinct but less spaced A-bands and areas with increased myosin intensity, probably indicating myosin accumulation, which diminished with time. The 2- and 5-wk-old adult myofibrils of heterozygous Mhc^K1728del/+ and Mhc^K1728del/Mhc¹⁰ flies display sarcomere fragmentation and dissolution of Z-disks. The 5-wk-old Mhc^K1728del/Mhc¹⁰ flies show myofibril atrophy. (Scale bars, 5 µm.)