Aging enhances indirect flight muscle fiber performance yet decreases flight ability in Drosophila.
Aging enhances indirect flight muscle fiber performance yet decreases flight ability in Drosophila.
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DOI：
10.1529/biophysj.108.130005
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发表时间：
2008-09
影响因子：
3.4
通讯作者：
Mark S. Miller;P. Lekkas;Joan M. Braddock;Gerrie P. Farman;B. Ballif;T. Irving;D. Maughan;J. Vigoreaux
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文献类型：
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作者：
Mark S. Miller;P. Lekkas;Joan M. Braddock;Gerrie P. Farman;B. Ballif;T. Irving;D. Maughan;J. Vigoreaux
我们从整个机体到肌动球蛋白跨桥研究了衰老对果蝇间接飞行肌的影响。中年（49天）苍蝇飞行受损，有正常的肌丝数量和包装，几乎没有更长的肌节，和轻微的线粒体退化相比，年轻的（3天）苍蝇。年老（56天）的果蝇不能拍打翅膀，超微结构恶化，线粒体严重受损，它们的皮肤纤维不能被钙激活。小振幅正弦长度扰动分析表明，中年间接飞行肌纤维开发大于两倍的等长力和功率输出的年轻纤维，但跨桥动力学相似。在主动、被动和严格条件下，弹性和粘性模量振幅的大幅增加表明中龄纤维在纵向上变得更硬。小角X-射线衍射表明，肌球蛋白头随着年龄的增长越来越多地向细丝移动，通过横桥形成增加的横向刚度。我们建议，所观察到的蛋白质组成的变化，连接丝，锚厚丝Z盘，产生补偿增加纵向刚度，等距张力，功率和肌动球蛋白相互作用，在老化的间接飞行肌肉。我们还推测，由于线粒体受损导致MgATP缺乏导致飞行性能下降。
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.