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。 我们的整个程序将X射线衍射(甘油天然纤维的X射线衍射)和 薄层扫描(速冻纤维和冷冻替代纤维)的研究 肌球蛋白交叉桥(肌肉S运动)的结构、排列和动态编排 分子)在水虫昆虫的飞行肌肉(IFM)中，具有无与伦比的结晶规律性。X- 射线模式与纤维在同一时间内快速冻结的平行电磁场相关 平衡状态，扰动或转变，以直接成像的形状和图案 十字桥，在这块肌肉中比任何其他肌肉都更清晰。最近的进展(附后)使我们保持镇定。 为了提出S著名的拉伸激活(SA)过程的未知结构触发因素， 这也可能为哺乳动物心肌的类似过程提供线索。一本出版的 RLX、ACT和RIG三个主要IFM州的X射线衍射图图库(PNAS，2008)也显示了同样的情况 通过两条不同的RLX？ACT途径达到ACT结构，即钙激活(在PCA 4.5)和 SA(在PCA 5.7)。关于SA(生物物理)循环工作循环形式的引人注目的新的X射线衍射片 Abst，2009)，在正弦2%/2赫兹长度变化的驱动下，显示出自行车强度在 多次反射，标志着交叉桥和原肌球蛋白的众所周知的主要作用。一个 由拉伸和保持长度步长触发的替代单发形式的SA现在是 支持工作环电影提出的模型，表明原肌球蛋白进入 在横桥开始附着并产生力量之前，打开位置。

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. Our overall program correlates X-ray diffraction (XRD, of glycerinated native fibers) and thin-section EM tomography (fibers quick-frozen & freeze-substituted) to characterize structure, arrangement and dynamic choreography of myosin crossbridges (muscle¿s motor molecules) in a waterbug insect flight muscle (IFM) of unexcelled crystalline regularity. X- ray patterns are correlated with parallel EM of fibers quick-frozen during the same equilibrium state, perturbation or transition, to image directly the shapes and patterns of crossbridges, clearer in this muscle than any other. Recent progress (attached) has poised us to suggest the unknown structural trigger for IFM¿s famous stretch-activation (SA) process, which may also throw light on the similar process in mammalian heart muscle. A published gallery (PNAS, 2008) of XRD patterns from 3 major IFM states, RLX, ACT & RIG, shows the same ACT structure reached by 2 distinct RLX¿ACT pathways, Ca2+ -activation (at pCa 4.5) and SA (at pCa 5.7). Striking new XRD "movies" of the cycling work-loop form of SA (Biophysics Abst, 2009), driven by sinusoidal 2%/2Hz length changes, show cycling intensity changes in multiple reflections that signal well-known major actions by crossbridges and tropomyosin. An alternate single-shot form of SA, triggered by a stretch-and-hold length-step, is now supporting the model suggested by the work-loop movies, indicating that tropomyosin moves into ON position before crossbridges begin to attach and generate force.