STEPWISE TRANSLATION OF MYOFIBRILS

这项拟议研究的长期目标是确定分子收缩卒中的大小和特征。这一目标在短期内可以通过测量单个肌原纤维的单个肌节缩短的不同步骤来实现，这项技术已经在这个实验室取得了成果。由于平行细丝之间的高度协同性，肌原纤维肌节中的平移是循序渐进的，显然与在单丝上的光学陷阱实验中发现的尺寸范围相同。因此，单个肌原纤维的台阶模式可能反映了收缩卒中产生的台阶。在恒定负荷下，单个肌原纤维的缩短步数将在单个肌节或单个半肌节的水平上测量。使用两种技术中的一种来检测这些步骤：光电二极管阵列或扫描检流镜加上光电倍增管。步长将在各种生理条件下确定，以确定这些条件对步长的影响。从结果中，我们将了解更多关于单个肌节收缩动力学的本质，也可能了解分子卒中的大小和特征。

The long-term goal of the proposed research is to determine the size and character of the molecular contractile stroke. This goal is approached in the short term by measurement of distinct steps of shortening in the single sarcomere of the single myofibril, a technique that has come into fruition in this laboratory. Because of high cooperativity among parallel thin filaments, translation in the myofibrillar sarcomere occurs in steps, apparently of the same size range as those found in optical trap experiments on single filaments. Thus, the stepping pattern in single myofibrils may reflect the step produced by the contractile stroke. Shortening steps in the single myofibril will be measured at the level of the single sarcomere or single half-sarcomere, at constant load. The steps are detected using one of two techniques: a photodiode array or a scanning galvanometer mirror plus photomultiplier. Step size will be determined under a variety of physiological conditions to determine how size is affected by these conditions. From the results we will learn much about the nature of contractile dynamics in the single sarcomere, and possibly also about the size and character of the molecular stroke.