Aging enhances indirect flight muscle fiber performance yet decreases flight ability in Drosophila

Biophys J. 2008 Sep;95(5):2391-401. doi: 10.1529/biophysj.108.130005. Epub 2008 May 30.


We investigated the effects of aging on Drosophila melanogaster indirect flight muscle from the whole organism to the actomyosin cross-bridge. Median-aged (49-day-old) flies were flight impaired, had normal myofilament number and packing, barely longer sarcomeres, and slight mitochondrial deterioration compared with young (3-day-old) flies. Old (56-day-old) flies were unable to beat their wings, had deteriorated ultrastructure with severe mitochondrial damage, and their skinned fibers failed to activate with calcium. Small-amplitude sinusoidal length perturbation analysis showed median-aged indirect flight muscle fibers developed greater than twice the isometric force and power output of young fibers, yet cross-bridge kinetics were similar. Large increases in elastic and viscous moduli amplitude under active, passive, and rigor conditions suggest that median-aged fibers become stiffer longitudinally. Small-angle x-ray diffraction indicates that myosin heads move increasingly toward the thin filament with age, accounting for the increased transverse stiffness via cross-bridge formation. We propose that the observed protein composition changes in the connecting filaments, which anchor the thick filaments to the Z-disk, produce compensatory increases in longitudinal stiffness, isometric tension, power and actomyosin interaction in aging indirect flight muscle. We also speculate that a lack of MgATP due to damaged mitochondria accounts for the decreased flight performance.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actin Cytoskeleton / physiology*
  • Actin Cytoskeleton / ultrastructure
  • Actomyosin / physiology*
  • Aging / physiology*
  • Animals
  • Drosophila melanogaster / physiology*
  • Drosophila melanogaster / ultrastructure
  • Female
  • Flight, Animal*
  • Isometric Contraction
  • Microscopy, Electron
  • Mitochondria / physiology
  • Mitochondria / ultrastructure
  • Myosins / physiology
  • Scattering, Small Angle
  • X-Ray Diffraction


  • Actomyosin
  • Myosins