INSECT FLIGHT MUSCLE HOT, COLD, PULLED AND PULLING

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 我们使用巨水虫Lethocerus(IFM)的间接飞行肌肉作为研究肌肉结构和功能的高度有序的模型系统。我们记录了松弛、僵硬和活动(等长收缩=pCa4.5处的高静态张力[HST])状态的甘油乳杆菌(IFM)的同步辐射X射线衍射图，以探索其结构动力学如何与包括青蛙骨骼肌(FSM)在内的脊椎动物肌肉的结构动力学相统一。使用5m相机，我们能够通过解析IFM 14.5 nm经向反射丰富的干涉分裂精细结构内的相对强度变化，来检测肌球蛋白头部质量朝向或远离肌球蛋白细丝中点的净轴向运动。当斜面拉伸1.5-2.0%时，弛豫态IFM的高被动刚度使被动张力维持在主动等轴测F0的30-60%，而14.5 nm间距和粗丝长度仅增加0.02%。因此，99%的松弛肌节延伸必须发生在将被动张力传递给粗丝的C-细丝/Z-带连接中。干涉测量未检测到松弛肌球蛋白头冠架内的填料或形状的变化。在松弛=等长激活时，IFM 14.5 nm经向变化不同于FSM的报道。间距拉长约0.07%(与FSM 1.3%相比)，总强度(由于附着头和分离头的混合)下降约40%(FSM变化？10%；分离头贡献不确定)。X射线干涉测量表明，平均IFM交叉桥角度或形状没有净变化(FSM基本上会重新排列)。在19.3 nm的层线上，第一行线斑点的10倍变亮标志着肌动蛋白靶区的交叉桥标记，而新的外部条纹标志着原肌球蛋白位移对细丝的立体解阻。对HST和Rigor的斜坡拉伸实验正在进行分析。这些结果可以与脊椎动物肌肉的结果进行比较和对比，以获得更统一的肌肉基本力产生事件的图景。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We use the indirect flight muscle of the giant water bug Lethocerus (IFM) as a highly ordered model system for studying muscle structure and function. We have recorded synchrotron x-ray diffraction patterns from relaxed, rigor and active (isometric contraction =High Static Tension [HST] at pCa4.5) states of glycerinated Lethocerus (IFM), to explore how its structural dynamics can unify with those of vertebrate muscles including frog skeletal muscle (FSM). Using a 5m camera we were able to detect net axial motions of myosin head mass toward or away from the myosin filament midpoint by resolving relative intensity changes within the rich interference-splitting fine structure of the IFM 14.5nm meridional reflection. When ramp-stretched 1.5-2.0%, the high passive stiffness of Relaxed-State IFM sustains passive tensions to 30-60% of active isometric F0, but the 14.5nm spacing and thick filament length increase together by only 0.02%. Thus 99% of relaxed sarcomere extension must occur in the C-filament/Z-band linkages that transmit passive tension to thick filaments. No change of packing or shape within crown-shelves of relaxed myosin heads is detected interferometrically. Upon Relaxed = Isometric Activation, IFM 14.5nm meridional changes differ from those reported for FSM. Spacing elongates ~0.07% (compared to FSM 1.3%), total intensity (due to mix of attached and detached heads) drops ~40% (FSM changes ¿¿10%; detached head contribution uncertain). X-ray interferometry signals no net change in averaged IFM crossbridge angle or shape (FSM rearranges substantially). On the 19.3 nm layer line, 10-fold brightening of the first row-line spot signals crossbridge labeling of actin Target Zones, while a new outer streak signals steric unblocking of thin filaments by a tropomyosin shift. Ramp-stretch experiments on HST and rigor are being analyzed. These results can be compared and contrasted with those from vertebrate muscle to achieve a more unified picture of the fundamental force generating events in muscle.