Confocal microscope

为了理解活细胞是如何工作的，有必要将其中发生的过程可视化。我们将使用一种专门的但功能强大的显微镜，共聚焦显微镜，来做到这一点。共聚焦显微镜通过排除来自其他水平的光，在细胞的单一水平上产生非常清晰的物体图像。技术的进步使得在活细胞中识别多种结构并跟踪它们变得更加容易。我们将利用这一技术来研究果蝇的两个过程：细胞分裂和神经细胞（神经元）之间的交流。复制染色体正确分离到子细胞对于遗传物质的正确传递至关重要。在人类卵子中，染色体分离的错误意味着后代不能正确发育，因为他们有错误的染色体数量。这样的错误也容易使分裂细胞变成肿瘤细胞。因此，染色体分离的机制对医学科学的关键方面是重要的。染色体分离成子细胞需要一种叫做纺锤体的特殊结构。虽然在一个多世纪前首次被发现，但我们才刚刚开始了解这种复杂分子机器的复杂性。纺锤体是一个双极结构，它的两极固定在两个未来的子细胞中。它是由微管构成的，微管是一种聚合物，复制的染色体沿着微管向两极移动。微管是动态的：它们生长和收缩，微管单体沿着它们的长度流动。它们的动态受到许多辅助蛋白的调控，包括把染色体拉到极点的运动蛋白。在纺锤体极点，微管与中心体相互作用。我们将研究中心体在细胞周期中是如何复制的。染色体有一个特殊的组成部分，即着丝点，它与有丝分裂纺锤体相互作用。着丝点为调节染色体附着到纺锤体及其传递的分子提供了一个平台，同时也为监控这一过程是否正确发生的分子提供了一个平台。细胞分裂是高度动态的，蛋白质可以通过添加磷酸基团，通过蛋白质激酶的作用，从一种活性状态切换到另一种活性状态。我们正在研究协调细胞分裂的蛋白激酶的作用。最后，一旦染色体分离到子细胞，细胞本身就会分裂，这一过程被称为细胞质分裂。这需要纺锤体发生变化，从而调节可收缩的环状结构的形成和收缩，而环状结构本身是由许多分子组成的。这项工作将研究主轴的各个组成部分之间的相互作用和这个收缩环带来的这一过程。神经通讯是正常脑功能和神经系统疾病的基础。使用共聚焦显微镜，我们将研究神经元是如何连接的。我们还将学习他们交流的一些方式。通讯依赖于从一个较大的膜的一小块区域发芽形成球形结构（囊泡）的能力，然后将囊泡运送到细胞中的另一个位置，在那里它与目标膜融合。当电信号到达神经末梢时，含有神经递质的囊泡与细胞膜融合，释放神经递质，激活下一个细胞。新的表面膜必须通过囊泡进入细胞内部的萌芽来恢复，在那里它们补充突触囊泡的供应。出芽还会将与细胞表面受体结合的信号分子内化，这样它们就可以进一步发出信号，或者被运送到它们被降解的地方。使用共聚焦显微镜，我们将监测受体、囊泡和它们移动的微管，以了解这种交通发生的机制，以及它如何促进神经元信号传导。

To understand how living cells work, it is essential to visualise the processes that go on in them. We will use a specialised but powerful type of microscopy, confocal microscopy, to do this. Confocal microscopy yields very clear images of objects at a single level in the cell, by excluding light from other levels. Advances in technology make it easier to identify multiple structures and follow them in living cells. We will use this technology to study two processes in the fruitfly Drosophila / cell division, and communication between nerve cells (neurons). The correct segregation of duplicated chromosomes to daughter cells is essential for correct transmission of the genetic material. In the human egg, mistakes in chromosome segregation mean that offspring do not develop correctly because they have the wrong number of chromosomes. Such mistakes also predispose dividing cells to become tumour cells. Thus the mechanisms of chromosome segregation are important for critical aspects of medical science. The segregation of chromosomes into daughter cells requires a specialised structure called the spindle. Although first discovered over a century ago, we are only beginning to understand the intricacies of this complex molecular machine. The spindle is a bipolar structure, its two poles anchored in the two future daughter cells. It is built from microtubules, polymers along which replicated chromosomes move towards the two poles. Microtubules are dynamic: they grow and shrink, and tubulin monomers flow along their length. Their dynamics are regulated by many accessory proteins, including motor proteins that pull the chromosomes to the poles. At the spindle poles, microtubules interact with a body known as the centrosome. We will study how the centrosome is duplicated during the cell cycle. Chromosomes have a specialised component, the kinetochore, that interacts with the mitotic spindle. The kinetochore provides a platform for molecules that mediate chromosome attachment to the spindle and their transmission, along with molecules that monitor whether this process occurs correctly. Cell division is highly dynamic and proteins can flip from one state of activity to another by the addition of phosphate groups through the action of enzymes known as protein kinases. We are studying the roles of the protein kinases that orchestrate cell division. Finally, once chromosomes are segregated to daughter cells, the cell itself divides in a process known as cytokinesis. This requires changes in the spindle that regulate formation and constriction of a contractile circular ring-structure that is itself built of numerous molecular components. This work will study the interactions between the various components of the spindle and this contractile ring to bring about this process. Neuronal communication is fundamental to both normal brain function and neurological disease. Using confocal microscopy, we will study how neurons are connected. We will also study some of the ways in which they communicate. Communication depends on the ability to bud off a small area of a larger membrane to form a spherical structure (a vesicle), and then to traffic the vesicle to another location in the cell where it fuses with a target membrane. When an electrical signal reaches a nerve terminal, vesicles that contain neurotransmitter fuse with the cell membrane, releasing neurotransmitter that activates the next cell. The new surface membrane must be recovered by budding of vesicles into the cell interior, where they replenish the supply of synaptic vesicles. Budding also internalises signaling molecules bound to receptors on the cell surface, so that they can signal further, or be trafficked to where they are degraded. Using confocal microscopy, we will monitor receptors, vesicles, and the microtubules that they move along, to understand the mechanisms by which this traffic occurs, and how it contributes to neuronal signalling.