Development and function of the zebrafish vestibular system across the life course

内耳是检测声音、重力和运动的感觉器官，使我们能够正确地听到并保持平衡。在耳朵内部，感觉毛细胞检测重力和身体在各个方向上的运动。这种感觉信息通过大脑传递给肌肉反射，使有机体保持平衡。内耳也被称为迷宫。耳朵的前庭(平衡)部分由三个光滑弯曲的管子--半规管导管--以及几个相互连接的感觉室组成，这些感觉室容纳着耳朵的感觉细胞。整个器官是一个连续的充满液体的腔。这种美丽而复杂的结构在所有脊椎动物中基本上都是相似的，从鱼类(我们在这里将其用作模型系统)到人类。内耳在胚胎中由一个简单的细胞球发育而来，将这种基本结构转化为成熟耳朵复杂迷宫的细胞和组织重组确实令人惊叹。细胞必须生长、弯曲、融合和重新排列。为了实现这一点，不同的细胞具有非常不同的大小和形状。必须严格控制这些事件，以确保在正确的地点和正确的时间产生正确的细胞类型和组织形状。我们在这项提案中的主要目标是使用尖端成像技术来描述和理解这些细胞重排。我们使用斑马鱼作为我们的模型系统，因为它非常适合这种成像方法。斑马鱼的胚胎是光学透明的，这意味着我们可以在显微镜下看到活动物的内脏，而不需要任何解剖。其次，我们可以用荧光蛋白标记细胞，在细胞发育过程中照亮不同的结构。通过使用专门的显微镜，我们可以测量随着整个器官在活胚胎中的发育，细胞形状和组织运动的动态变化。我们将在鱼的整个生命过程中进行这些研究，包括胚胎发生、变态和成体期间的事件。该项目的一个主要目标是开发和与工程师建立新的联系，工程师将利用我们的成像数据开发计算机模型，说明细胞如何改变形状、移动、融合和重新排列，以形成耳朵的精细结构。我们还希望了解在胚胎形成过程中控制耳朵发育的遗传因素。在我们之前的工作中，我们已经确定了一些对半规管系统的发育至关重要的基因。我们的一些鱼类品系在这些基因中携带特定的基因突变：我们将在上述成像和计算机模拟实验中使用这些突变鱼类，以获得新的见解，了解随着内耳的发育，基因功能如何影响细胞运动、细胞分裂和细胞形状。最终目标是将我们的成像数据与鱼类的前庭行为联系起来。我们的几个遗传菌株在半规管系统中发育有解剖缺陷，并有轻微的平衡缺陷。我们将使用这些鱼来了解耳朵对平衡功能的贡献，使用游泳行为的自动跟踪。这将使我们对耳朵平衡系统的功能以及它与视觉和其他功能相比的相对重要性有新的见解。尽管前庭疾病很常见，并会导致重大的临床问题，但与耳朵的听觉(听力)部分相比，前庭(平衡)系统的研究严重不足。这个项目将有助于纠正这一差异，并将有助于建立知识库，以支持我们对人类内耳在健康和疾病方面的理解。我们还致力于揭示基本的发育原理，这些原理将提高我们对器官系统是如何从发育中的胚胎的细胞片建立起来的理解。

The inner ear is the sensory organ that detects sound, gravity and motion, enabling us to hear and to balance correctly. Within the ear, sensory hair cells detect gravity together with body movement in all directions. This sensory information is relayed, via the brain, to muscular reflexes to enable an organism to maintain balance.The inner ear is rightly also called the labyrinth. The vestibular (balance) part of the ear consists of three smoothly curved tubes-the semicircular canal ducts-together with several interlinked sensory chambers, which house the sensory cells of the ear. The whole organ is one continuous fluid-filled cavity. This beautiful and intricate structure is essentially similar in all vertebrate organisms, from the fish (which we use here as a model system) through to humans. The inner ear develops in the embryo from a simple ball of cells, and the cell and tissue rearrangements that convert this rudimentary structure into the complex labyrinth of the mature ear are truly remarkable. Sheets of cells must grow, bend, fuse and rearrange. Different cells take on widely differing sizes and shapes to achieve this. These events must be tightly controlled to ensure that the correct cell types and tissue shapes are produced in the right place and at the right time. Our primary aim in this proposal is to use cutting-edge imaging technology to describe and understand these cellular rearrangements. We use the zebrafish as our model system, as it is beautifully suited to this imaging approach. The zebrafish embryo is optically clear, meaning that we can see internal organs in the live animal under the microscope, without any need for dissection. Secondly, we can label cells with fluorescent proteins, lighting up different structures as they develop. By using specialised microscopes, we can measure dynamic changes in cell shapes and tissue movements as the whole organ develops in the live embryo. We will undertake these studies across the life course of the fish, including events during embryogenesis, metamorphosis and adulthood.A major goal of the project is to develop and forge new links with engineers, who will use our imaging data to develop computer models of how cells change shape, move, fuse and rearrange to form the elaborate structures of the ear.We also wish to understand the genetic factors that control ear development during embryogenesis. In our previous work, we have identified a number of genes that are critical for development of the semicircular canal system. A number of our fish strains carry specific genetic mutations in these genes: we will use these mutant fish in the imaging and computer modelling experiments described above, to gain new insights into how gene function affects cell movement, cell division and cell shape as the inner ear develops.A final aim is to correlate our imaging data with vestibular behaviour in our fish. Several of our genetic strains develop with anatomical defects in the semicircular canal system, and have mild balance defects. We will use these fish to understand the contribution of the ear to balance function, using automated tracking of swimming behaviour. This will give us new insights into the function of the balance system of the ear, and its relative importance compared with visual and other functions.Research on the vestibular (balance) system is hugely under-represented compared with that on the auditory (hearing) part of the ear, despite the fact that vestibular disorders are common and cause significant clinical problems, especially in the elderly. This project will help to redress that discrepancy and will contribute to the knowledge base that underpins our understanding of the human inner ear in both health and disease. We also aim to uncover fundamental developmental principles that will improve our understanding of how organ systems are built from sheets of cells in the developing embryo.