Evolution of Developmental Processes Governing Head Formation

博德9723660在过去的10-15年里，人们对调节胚胎发育为正常动物的基因和过程有了很大的了解。积累知识最有趣的方面之一是，到目前为止所研究的后生动物的许多发育过程中，涉及一组共同的或相关的机制的一组共同的调控基因。这些共同的特征提出了有趣而重要的问题，即这些基因是在进化过程中多早出现的？他们已经出现在乌尔后生动物中了吗？他们参与了哪些发展机制和发展过程？以及，这些机制和过程在多大程度上是早期发明的，并通过动物进化保存下来的？解决这些问题的一种方法是研究这些基因及其在后生动物进化过程中很早就出现的动物群体中的功能，例如线虫，其成员包括水母、海葵和淡水海蛇。其中，多头蛇特别有用，因为人们对发育过程(模式形成、控制几种细胞类型的增殖和分化)非常了解。此外，已知在许多脊椎动物和无脊椎动物中调节发育事件的一些基因也被分离出来，并且部分地在九头蛇中具有特征。这项拟议工作的总体目标是确定多头蛇头部发育的基因和机制是否与脊椎动物和昆虫头部发育中的基因和机制相似。已经发现了一个这样的基因。Cnotx是OTX家族成员中的一种九头蛇同系物，已被鉴定并表明参与了触须的发育，触须是九头蛇头的一种特殊结构。也有证据表明，DLX和EMX家族的同源物存在于九头蛇或近亲的海洋中。这些家族的基因在脊椎动物和节肢动物的头部模式中扮演着重要的角色。具体目标有两个。一种是详细研究Coots基因在多头蛇头部模式形成中的作用，以及研究它在细胞周期穿越中的作用，初步证据表明它具有这种作用。这些努力将通过各种方法进行，包括检查组织操作和功能研究期间表达模式的变化。另一项是分离和鉴定与多头蛇头部发育有关的其他基因的作用。重点将放在上述家族的基因上。

Bode 9723660 During the last 10-15 years a great deal has been learned about the genes and processes that regulate the development of an embryo into a functioning animal. One of the most interesting aspects of the accumulating knowledge is that a common set of regulatory genes involved in a common, or related, set of mechanisms underlie many of the developmental processes of the metazoans studied so far. These common features raise interesting and important questions as to how early during evolution did these genes arise? Were they already present in the Ur-metazoan? What developmental mechanisms and developmental processes did they participate in? And, to what extent were the mechanisms and processes invented early and conserved through animal evolution? One approach to these issues is to study these genes and their functions in organisms that belong to groups of animals that arose very early during metazoan evolution, such as the cnidaria, whose members include jellyfish, sea anemones, and the freshwater hydra. Of these, hydra, is particularly useful since the developmental processes (pattern formation, control of the proliferation and differentiation of the several cell types) are well-understood. Further, a number of genes known to regulate developmental events in many vertebrates and invertebrates have also been isolated, and in part, characterized in hydra. The overall aim of the proposed work is to determine if the genes and mechanisms underlying the development of the head of hydra are similar to those found in the development of the heads of vertebrates and insects. One such gene has already been found. Cnotx a hydra homologue, of the members of the Otx family has been characterized and shown to be involved in the development of the tentacles, a particular structure of the hydra head. There is also evidence that homologues of the Dlx and Emx families exist in hydra, or a close marine relative. Genes of these families play important roles in the patterning of the head in vertebrates and arthropods. The detailed aims are two. One is to examine in the role of the Coots gene in patterning of the hydra head in detail as well as to investigate its role in cell cycle traverse, a role that preliminary evidence suggests it has. These efforts will be pursued with a variety of approaches including examining alterations of expression patterns during tissue manipulations and functional studies. The other is to isolate and characterize the role of other genes involved in head development in hydra. The focus will be on genes of the families mentioned above.