Exon 3a has been replaced by cDNA sequences encoding exon 3b.
flightless, with Mhc10
The myofibrillar ultrastructure in the indirect flight muscle of animals carrying MhcEMB-3b in a Mhc10 background is identical to wild type at the pupal stage. However, 2 days after eclosion, the filament packing is disrupted, and the normal rigid hexagonal arrangement of thick and thin filaments is disturbed. The myofibrils appear cracked and frayed when viewed longitudinally, because of gaps between thick and thin filaments and/or loss of thick and thin filaments. The phenotype becomes progressively worse with age.