Molecular and cellular biology of dynamics and mechanisms of myofibrillogenesis

1.鸡胚胎体节肌原纤维蛋白的出现顺序：免疫荧光显微镜观察发现，鸡颈部体节中构成肌原纤维的蛋白不是同时合成的，成体亚型基因表达的启动不依赖于主要肌原纤维蛋白的出现完成。2.肌钙蛋白和肌营养不良蛋白在再生肌肉中的表达：在成年鸡的慢肌(背阔肌前肌)和快肌(背阔肌后肌)的再生纤维中，胚胎肌钙蛋白的表达早于肌钙蛋白的表达，并晚于肌营养不良蛋白与正常肌肉纤维的形态相同的成体肌钙蛋白异构体。此外，尽管失神经肌肉中的再生纤维与神经支配的m…中的肌钙蛋白表达类似更常见的是，他们中的许多人再次恢复到胚胎状态。然而，在神经完整的再生纤维和切除神经的再生纤维中，dystrophin的表达没有差异。因此，肌钙蛋白和肌营养不良蛋白基因的表达在再生过程中是独立调节的，而神经是前者蛋白质充分发育所必需的，而后者是不需要的。3.肌纤维形成过程中的蛋白动态：免疫金电子显微镜显示，金标记分别出现在近端肌原纤维的A带和A-I连接水平。因此，肌动蛋白和肌球蛋白的聚合似乎分别与肌球蛋白细丝和肌原纤维的A-I连接区有关。罗丹明标记的肌肉和非肌肉肌动蛋白显微注射到培养的鸡心肌细胞和成纤维细胞中的荧光恢复(FR)研究表明，应激纤维比肌原纤维具有更快的荧光恢复；在肌原纤维中，肌肉肌动蛋白的荧光恢复比非肌肉肌动蛋白快，新生肌原纤维显示不同的荧光恢复；应激纤维的近端和末端的荧光恢复与肌肉和非肌肉肌动蛋白相似。较少

1.Order of appearance of myofibrillar proteins in embryonic chicken somites : Immunofluorescence microscopy revealed that in chicken cervical somites the proteins constituting myofibrils are not synthesized simultaneously and the turning-on of the gene expression of the adult isoforms was not dependent on the completion of the appearance of the major myofibrillar proteins. In situ hybridization showed that cardiac type troponin C mRNA appeared one stage (about 3 hours) earlier than its protein.2.Troponin and dystrophin in regenerating muscle : In regenerating fibers of the slow (anterior latissimus dorsi) and fast (posterior latissimus dorsi) muscles of adult chickens, embryonic troponin was expressed earlier than dystrophin and changed to its adult isoform later than the stage when dystrophin exhibited the same appearance as that in normal muscle fibers. Further, although regenerating fibers in denervated muscle switched on the expression of troponin similarly to those in innervated m … More uscle, many of them again reverted to an embryonic state. However, no difference was found in the dystrophin expression between regenerating fibers with nerves intact and those with nerves resected. Thus, it appears that the expression of troponin and dystrophin genes in regulated independently during regeneration and nerves are required for the full development of the former protein while unnecessary for the latter.3.Protein dynamics during myofibrillogenesis : Immunogold electron microscopy of cardiomyocytes microinjected with biotin-actin and -myosin showed that gold labeling was first found at the A band and the A-I junctional level of proximal myofibrils, respectively. Thus, polymerization of actin and myosin seems to occur in association with myosin filaments and with A-I junctional regions of myofibrils, respectively. Fluorescence recovery (FR) study of rhodamine-labeled muscle and nonmuscle actins microinjected into cultured chicken cardiomyocytes and fibroblasts showed that stress fibers had faster FR than myofibrils ; in myofibrils FR of muscle actin was faster than that of nonmuscle actin, and nascent myofibrils displayd different FR ; and stress fibers had similar FR at both proximal and terminal portions with both muscle and nonmuscle actins. Less