Evolutionary origins of coordination: physiological and molecular studies on sponges (Porifera)

海绵是现存最原始的动物Porifera的成员。海绵是唯一一种没有神经系统的多细胞动物，但它们有各种各样的缓慢行为，使它们能够排泄废物。海绵的第一个基因组是可用的，其中有许多我们在其他动物的神经系统中看到的分子。我和我的学生们感兴趣的是海绵前神经系统是如何组织起来的，以及它们在海洋中的行为是如何起作用的，一直到涉及环境中感知信号的膜通道，以及涉及单个细胞之间交流的机制。这有助于我们理解最初的神经系统是如何进化的。我们最近在海绵中发现了一种新的感觉细胞，它有可能阐明动物如何感知流速以控制流体运动，例如在毛细血管和肾小管中。该提案将研究a)参与海绵细胞间信号传递的分子，以及细胞上可接收信号的受体；B)海绵用来建立过滤系统的分子机制；c)引导海绵体形成的流体流动物理参数。将海绵中发现的基因与具有第一个神经系统的动物（水母-刺胞动物）的基因进行比较，突出了即使没有传统神经，动物在信号传导方式上的惊人相似性。例如，我们自己的研究表明，海绵利用谷氨酸和伽马氨基丁酸来刺激和抑制组织收缩，就像高等动物一样。我们提出的研究计划侧重于确定细胞之间发生信号传导的区域（是否存在“原突触”？），并最终确定在发育中和成年海绵中产生参与信号传导的新细胞的位置。

Sponges are members of the Porifera, the most primitive extant animals. Sponges are the only group of multicellular animals without a nervous system yet they have various types of slow behaviour that allow them to excrete wastes. The first genome of a sponge is just available, and in it are many molecules that we see in nervous systems in other animals. My students and I are interested in how the sponge pre-nervous systems is organized and functions in their behaviour in the ocean down to the membrane channels involved in sensing signals in the environment and the mechanisms involved in communication between individual cells. This helps us understand how the first nervous systems evolved. We recently found a new sensory cell in sponges which has the potential to clarify how animals sense flow rates in order to control fluid movement, for example in blood capilliaries and kidney tubules. This proposal will investigate a) the molecules involved in signaling between cells in the sponge, and the receptors available to receive signals on cells; b) the molecular mechanisms which sponges use to build the filtration system; and c) the physical parameters of fluid flow that guide the formation of the sponge body. Comparing genes found in sponges with those in animals with the first nervous systems (jellyfish - cnidarians) has highlighted remarkable similarities in the way signaling works in animals even without conventional nerves. Our own work for example has shown that sponges use glutamate and GABA to stimulate and inhibit contractions of tissues, just as in higher animals. Our proposed research program focuses on identifying the regions where signaling occurs between cells (is there a 'proto-synapse'?) and ultimately determining where new cells involved in signaling are produced in developing and in adult sponges.