Ward Bryan K, Tan Grace X-J, Roberts Dale C, Della Santina Charles C, Zee David S, Carey John P
Department of Otolaryngology - Head & Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America.
PLoS One. 2014 Mar 19;9(3):e92109. doi: 10.1371/journal.pone.0092109. eCollection 2014.
Zebrafish (Danio rerio) offer advantages as model animals for studies of inner ear development, genetics and ototoxicity. However, traditional assessment of vestibular function in this species using the vestibulo-ocular reflex requires agar-immobilization of individual fish and specialized video, which are difficult and labor-intensive. We report that using a static magnetic field to directly stimulate the zebrafish labyrinth results in an efficient, quantitative behavioral assay in free-swimming fish. We recently observed that humans have sustained nystagmus in high strength magnetic fields, and we attributed this observation to magnetohydrodynamic forces acting on the labyrinths. Here, fish were individually introduced into the center of a vertical 11.7T magnetic field bore for 2-minute intervals, and their movements were tracked. To assess for heading preference relative to a magnetic field, fish were also placed in a horizontally oriented 4.7T magnet in infrared (IR) light. A sub-population was tested again in the magnet after gentamicin bath to ablate lateral line hair cell function. Free-swimming adult zebrafish exhibited markedly altered swimming behavior while in strong static magnetic fields, independent of vision or lateral line function. Two-thirds of fish showed increased swimming velocity or consistent looping/rolling behavior throughout exposure to a strong, vertically oriented magnetic field. Fish also demonstrated altered swimming behavior in a strong horizontally oriented field, demonstrating in most cases preferred swimming direction with respect to the field. These findings could be adapted for 'high-throughput' investigations of the effects of environmental manipulations as well as for changes that occur during development on vestibular function in zebrafish.
斑马鱼（Danio rerio）作为内耳发育、遗传学和耳毒性研究的模式动物具有诸多优势。然而，使用前庭眼反射对该物种的前庭功能进行传统评估时，需要用琼脂固定单个鱼体并配备专门的视频设备，操作困难且劳动强度大。我们报告称，使用静磁场直接刺激斑马鱼内耳迷路可在自由游动的鱼中实现高效、定量的行为测定。我们最近观察到人类在高强度磁场中会出现持续性眼球震颤，我们将这一观察结果归因于作用于迷路的磁流体动力学力。在此，将鱼个体引入垂直的11.7T磁场孔中心，每次间隔2分钟，并跟踪它们的运动。为了评估相对于磁场的游动方向偏好，还将鱼置于水平方向的4.7T磁体中并处于红外（IR）光下。在庆大霉素浴后对一部分鱼再次进行磁体测试，以消除侧线毛细胞功能。自由游动的成年斑马鱼在强静磁场中表现出明显改变的游泳行为，这与视觉或侧线功能无关。三分之二的鱼在暴露于强垂直磁场的整个过程中游泳速度增加或出现持续的打转/翻滚行为。鱼在强水平磁场中也表现出改变的游泳行为，在大多数情况下表明相对于磁场有偏好的游泳方向。这些发现可用于对环境操纵影响以及斑马鱼发育过程中前庭功能变化的“高通量”研究。
