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Title: Aging Enhances Indirect Flight Muscle Fiber Performance yet Decreases Flight Ability in Drosophila

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.
Authors:
; ; ; ; ; ; ;  [1] ;  [2]
  1. (IIT)
  2. (
Publication Date:
OSTI Identifier:
1006827
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biophys. J.; Journal Volume: 95; Journal Issue: 2008
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES; 60 APPLIED LIFE SCIENCES; AGING; AMPLITUDES; CALCIUM; DROSOPHILA; FIBERS; FLEXIBILITY; FLIES; KINETICS; MITOCHONDRIA; MUSCLES; MYOSIN; PERFORMANCE; PROTEINS; X-RAY DIFFRACTION