Identifying conserved mechanisms of cranial muscle morphogenesis using the zebrafish

人类的面部表情有很大的变化范围，从喜悦到悲伤、惊讶和困惑。这些表情是由大量肌肉的协调运动引起的，这些肌肉也是说话、吃饭和看东西所必需的。面部的每块肌肉都附着在头骨上的特定位置，这种特异性对于肌肉的正确功能至关重要。虽然动物头部的形成已经研究了200多年，但仍然不清楚头部肌肉是如何定位的，以及哪些因素调节这一过程。这项提议的主要目的是发现脊椎动物头部的肌肉在发育过程中如何正确定位，然后附着在头骨和下颌的适当部位。该提案的主要目标和技术是：1）描述斑马鱼头部肌肉的形成方式。我将观察头部肌肉在发育过程中形成的过程，用彩色荧光染料标记它们。然后，我可以测试头部的其他组织，如骨骼或肌腱，是否对定位肌肉很重要，具体方法是用激光去除它们。2)显示斑马鱼头部肌肉是否被特定因素引导到正确位置。为了测试一个因素是否对头部肌肉的发育很重要，我将在发育过程中改变其功能，并显示这是否会导致肌肉定位和附着在头骨上的变化。3)显示了所有脊椎动物头部肌肉发育所需的因素。我将显示，如果因素的重要性，定位斑马鱼头部肌肉有类似的作用，在其他两个代表的动物王国：一个原始的鱼（角鲨）和鸟（小鸡）。我使用斑马鱼胚胎作为我的模型系统，因为在透明的胚胎中很容易观察到头部的发育，并且它有一个相当简单的头部组织。这项工作将在伦敦国王学院发育神经生物学中心与Susan古特里教授和Anthony Graham教授合作进行。我们将结合我们在头部发育方面的专业知识，为脊椎动物的头部肌肉如何正确定位并附着在头骨上提供一个模型。尽管成年脊椎动物的头部之间存在明显差异，但在发育早期，所有脊椎动物胚胎（包括鱼类，鸟类和人类）的头部都非常相似。这是因为所有的脊椎动物都有一个共同的祖先，并且它们继承了该祖先的许多结构。通过比较不同动物之间的头骨或下巴等结构，我们可以识别所有脊椎动物可能拥有的共同特征。几乎总是，这些共同的特征在不同动物的胚胎中通过相同的细胞运动和排列过程产生。反过来，这些过程在不同的动物中由相同的因素控制。这意味着，如果我能找到控制肌肉在斑马鱼、角鲨和鸡头部正确定位的因素，那么它们很可能在所有脊椎动物中都是一样的，包括人类。很可能所有动物都使用相同的因素来定位肌肉，但脊椎动物的头部在肌肉附着方面表现出相当大的差异，部分原因是动物有不同的食物来源和生活方式。这些肌肉附着的差异以及这些肌肉的不同功能是如何产生的？我想看看这些差异，来展示肌肉是如何附着在不同物种头骨上的不同点上的。这些肌肉位置的差异导致了动物进食和交流方式的巨大变化。因此，我希望我的工作最终能让我们了解我们是如何获得微笑和相互交谈的能力的。

The human face is capable of a huge range of expressions from joy through to sadness, surprise and confusion. These expressions are caused by the coordinated movement of a large number of muscles, which are also required for talking, eating and looking. Each muscle in the face attaches to a specific location on the skull and this specificity is vital for the correct function of the muscle. Although the formation of heads in animal development has been studied for over 200 years, it is still not clear how the head muscles are positioned and which factors regulate this process. The principal aim of this proposal is to discover how the muscles in heads of animals with backbones (vertebrates) become correctly positioned during development and then attach to the appropriate points on the skull and jaw. The key aims and techniques of this proposal are: 1) describe how the head muscles form in zebrafish. I will observe head muscles as they form during development by labelling them with a coloured fluorescent dye. I can then test if other tissues in the head, such as bone or tendons, are important for positioning the muscles by specifically removing them using a laser. 2) show whether zebrafish head muscles are guided to their correct position by specific factors. To test if a factor is important for head muscle development, I will alter its function during development and show if this causes a change in muscle positioning and attachment to the skull. 3) show which factors are required for head muscle development in all vertebrates. I will show if factors important for positioning of zebrafish head muscles have similar roles in two other representatives of the animal kingdom: a primitive fish (dogfish) and a bird (chick). I use zebrafish embryos as my model system because development of the head is easy to observe in the transparent embryos and it has a fairly simple head organisation. This work will be performed at the Centre for Developmental Neurobiology at Kings College London in collaboration with Professor Susan Guthrie and Professor Anthony Graham. We will bring to bear our combined expertise of head development to provide a model for how the head muscles become properly positioned and attached to the skull in vertebrates. Despite obvious differences between the heads of adult vertebrates, early in development the heads of all vertebrate embryos, including fish, birds and humans, are very similar. This is because all vertebrates have a common ancestor and they have inherited many structures that were present in that ancestor. By comparing these structures such as the skull or jaw, between different animals, we can identify shared features that all vertebrates will be likely to possess. Almost always, these shared features arise in the embryos of different animals by the same process of cell movement and arrangement. These processes in turn, are controlled by the same factors, in different animals. This means that if I can find the factors that control how muscles are correctly positioned in the head of a zebrafish, a dogfish and a chicken, it is likely that they will be the same in all vertebrates, including humans. It is highly possible that all animals use the same factors for positioning of the muscles, BUT vertebrate heads show considerable variation in how the muscles attach, partly because animals have different food sources and lifestyles. How do these differences in muscle attachment and hence different functions of these muscles arise? I want to look at these differences, to show how the muscles attach to different points on the skull in different species. These differences in muscle positioning have lead to dramatic changes in how animals eat and communicate. As a consequence, I hope that my work will eventually lead to an understanding of how we gained the ability to smile and talk to each other.