Asymmetric mechanotransduction by hair cells of the zebrafish lateral line (Part 2/2)

In the lateral line system, water motion is detected by neuromast organs, fundamental units that are arrayed on a fish’s surface. Each neuromast contains hair cells, specialized mechanoreceptors that convert mechanical stimuli, in the form of water movement, into electrical signals. The orientation of hair cells’ mechanosensitive structures ensures that the opening of mechanically-gated channels is maximal when deflected in a single direction. In each neuromast organ, hair cells have two opposing orientations, enabling bi-directional detection of water movement. Interestingly, Tmc2b and Tmc2a proteins, which constitute the mechanotransduction channels in neuromasts, distribute asymmetrically so that Tmc2a is expressed in hair cells of only one orientation. Here, using both in vivo recording of extracellular potentials and calcium imaging of neuromasts, we demonstrate that hair cells of one orientation have larger mechanosensitive responses. The associated afferent neuron processes that ..., , Electrophysiology traces will require Clampfit or another equivalent program to open. Matlab can also be used.在侧线系统（lateral line system）中，水体运动由神经丘器官（neuromast organs）感知，这类基本功能单位排布于鱼类体表。每个神经丘均包含毛细胞（hair cells）——一类特化的机械感受器（mechanoreceptors），可将水体运动形式的机械刺激转换为电信号。毛细胞机械敏感结构（mechanosensitive structures）的定向排布，可确保机械门控通道（mechanically-gated channels）在向单一方向偏转时达到最大开放状态。在单个神经丘器官内，毛细胞存在两种相反的定向类型，从而实现对水体运动的双向感知。值得注意的是，构成神经丘内机械转导通道（mechanotransduction channels）的Tmc2b与Tmc2a蛋白呈现不对称分布，其中仅在一种定向类型的毛细胞中表达Tmc2a。本研究通过神经丘的在体细胞外电位记录（in vivo recording of extracellular potentials）与钙成像（calcium imaging）两种实验手段，证实某一特定定向类型的毛细胞具备更强的机械敏感响应。与之相关的传入神经元突起…… 电生理记录轨迹需使用Clampfit或其他等效程序打开，也可通过Matlab进行处理。