41.9kb fragment including the Mhc gene and about 9kb of 5' and 3' flanking sequences.
Flies expressing Mhc+t41.9 display a normal sarcomeric structure.
Overexpression of Mhc in wild type flies (three copies) does not affect muscle function but may have slight effects upon myofibril organisation. Four copies has a severe effect on flight and jump ability reflecting mutant myofibrils in the indirect flight muscles (IFMs) and tergal depressor muscle of the trochanter (TDT). Only occasionally flies carrying five copies are observed and flies carrying six copies are never recovered. This indicates overexpression of Mhc can affect muscles in addition to the IFMs and TDT.
Expression of Mhc+t41.9 rescues the dorsal longitudinal muscle defects seen in MhcL1736P mutant flies. The flightlessness is not rescued.
Expression of two copies of Mhc+t41.9 rescues the dorsal longitudinal muscle thinning seen in homozygous MhcE1570K mutants, with flies instead showing a similar hypercontraction phenotype to that seen in MhcE1570K heterozygotes. Expression of Mhc+t41.9 partially suppresses the sarcomere disruption seen in MhcE1570K mutants.
Expression of Mhc+t41.9 partially rescues the hypercontraction phenotype seen in MhcE1570K/+ mutants, with flies displaying less fibre tearing.