Institute of Vegetative Physiology, University of Cologne, Cologne 50931, Germany.
J Gen Physiol. 2011 Mar;137(3):255-70. doi: 10.1085/jgp.201010568.
The zebrafish is a potentially important and cost-effective model for studies of development, motility, regeneration, and inherited human diseases. The object of our work was to show whether myofibrils isolated from zebrafish striated muscle represent a valid subcellular contractile model. These organelles, which determine contractile function in muscle, were used in a fast kinetic mechanical technique based on an atomic force probe and video microscopy. Mechanical variables measured included rate constants of force development (k(ACT)) after Ca(2+) activation and of force decay (τ(REL)(-1)) during relaxation upon Ca(2+) removal, isometric force at maximal (F(max)) or partial Ca(2+) activations, and force response to an external stretch applied to the relaxed myofibril (F(pass)). Myotomal myofibrils from larvae developed greater active and passive forces, and contracted and relaxed faster than skeletal myofibrils from adult zebrafish, indicating developmental changes in the contractile organelles of the myotomal muscles. Compared with murine cardiac myofibrils, measurements of adult zebrafish ventricular myofibrils show that k(ACT), F(max), Ca(2+) sensitivity of the force, and F(pass) were comparable and τ(REL)(-1) was smaller. These results suggest that cardiac myofibrils from zebrafish, like those from mice, are suitable contractile models to study cardiac function at the sarcomeric level. The results prove the practicability and usefulness of mechanical and kinetic investigations on myofibrils isolated from larval and adult zebrafish muscles. This novel approach for investigating myotomal and myocardial function in zebrafish at the subcellular level, combined with the powerful genetic manipulations that are possible in the zebrafish, will allow the investigation of the functional primary consequences of human disease-related mutations in sarcomeric proteins in the zebrafish model.
斑马鱼是研究发育、运动、再生和遗传性人类疾病的一种潜在重要且具有成本效益的模式生物。我们的工作目的是证明从斑马鱼横纹肌中分离出来的肌原纤维是否代表一种有效的亚细胞收缩模型。这些细胞器决定了肌肉的收缩功能，我们将其用于一种基于原子力探针和视频显微镜的快速动力学机械技术中。测量的力学变量包括 Ca2+ 激活后力发展的速率常数 (kACT) 和 Ca2+ 去除时力衰减的速率常数 (τREL(-1))、最大或部分 Ca2+ 激活时的等长力 (Fmax) 以及施加于松弛肌原纤维的外力响应 (Fpass)。来自幼虫的肌节肌原纤维产生的主动力和被动力大于来自成年斑马鱼的骨骼肌原纤维，这表明肌节肌肉的收缩细胞器发生了发育变化。与鼠心肌肌原纤维相比，成年斑马鱼心室肌原纤维的测量结果表明，kACT、Fmax、力的 Ca2+ 敏感性和 Fpass 相当，而 τREL(-1) 较小。这些结果表明，斑马鱼的心肌肌原纤维与鼠心肌肌原纤维一样，是研究肌节水平心脏功能的合适收缩模型。这些结果证明了从斑马鱼幼体和成年肌肉中分离的肌原纤维进行力学和动力学研究的实用性和有效性。这种在亚细胞水平研究斑马鱼肌节和心肌功能的新方法，结合在斑马鱼中可能进行的强大遗传操作，将允许在斑马鱼模型中研究与人类疾病相关的肌节蛋白突变对心脏功能的功能主要影响。
