X-RAY DIFFRACTION STUDIES OF FLIGHT MUSCLE OF MANDUCA

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 天蛾，Manduca sexta，是一种流行的综合生物学研究模式系统。与许多其他昆虫不同，飞行肌肉是同步的，即收缩对单个神经冲动的反应类似于脊椎动物骨骼肌。Manduca飞行肌肉的长度张力关系与哺乳动物的心肌非常相似，值得作为一种潜在的模型系统进行研究。然而，它还有许多其他耐人寻味的特点。运动肌肉的新陈代谢产热与体表热损失必然会导致温度梯度。这种现象发生在Manduca中与机翼下沉有关的主要飞行肌肉(背纵肌：DLm)。这些肌肉在最温暖的腹侧亚单位和最冷的背侧亚单位之间形成了5.6摄氏度的平均温差。这种温度差异导致机械差异，与DLm的腹侧亚单位相比，背侧亚单位的收缩速率和机械功率输出减少。这些结果表明，背侧DLMS可能不主要与翼抑制有关。也许相反，背侧的亚单位，由于交叉桥更多地附着在细丝上，起着弹簧的作用。因此，在收缩结束时，它们可能会与相互对抗的背腹肌一起动作，以抬高翅膀。为了解决这个问题，我们进行了时间分辨的小角X射线光纤衍射研究，我们实时监测了跨桥的运动。同时，对带皮肤的Manduca飞行肌肉进行的实验研究了可以与包括哺乳动物心肌在内的其他肌肉相比较的基本生理特征。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The hawkmoth, Manduca sexta, is a popular model system for studies in integrative biology. Unlike many other insects, the flight muscles are synchronous, i.e. contractions respond to individual nerve impulses similarly to vertebrate skeletal muscle. The length tension relationship of Manduca flight muscle is remarkably similar to mammalian cardiac muscle making it worth investigating as a potential model system. It has a number of other intriguing features, however. Metabolic heat production in locomotor muscles paired with surface heat loss necessarily leads to a temperature gradient. This phenomenon occurs in the dominant flight muscles involved in wing depression (dorsolongitudinal muscles: DLM) in Manduca. These muscles develop an average temperature difference of 5.6 degrees C between the warmer, ventral-most and the cooler, dorsal-most subunits. This temperature difference leads to a mechanical difference where the dorsal subunits operate with decreased contractile rates and reduced mechanical power output compared with the ventral subunits of the DLM. These results suggest that the dorsal DLMs may not be primarily involved with wing depression. Perhaps instead, the dorsal subunits, with cross-bridges remaining more attached to the thin filaments, behave as springs. Thus, at the end of the contraction they may act in concert with the antagonistic dorsoventral muscles to elevate the wings. To address this question, we conducted time-resolved small-angle x-ray fiber diffraction studies for which we monitored the movement of cross-bridges in real time. In parallel, experiments on skinned manduca flight muscle investigate basic physiological characteristics that can be compared to other muscles, including mammalian myocardium.