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

海绵是Porifera的成员，是现存的最原始的动物。海绵是唯一一类没有神经系统的多细胞动物，但它们的各种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，它们在海洋中的行为是如何运作的，从参与感知环境信号的膜通道到单个细胞之间的通信机制都很感兴趣。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液体运动，例如在毛细血管和肾小管中。这项提议将研究a)海绵细胞之间的信号传递所涉及的分子，以及可用于接收细胞上的信号的受体；b)海绵用来建立过滤系统的分子机制；以及c)引导海绵小体形成的流体的物理参数。将海绵中发现的基因与具有第一神经系统的动物(水母-线虫)中发现的基因进行比较，突显出即使在没有传统神经的情况下，动物的信号传递方式也有显著的相似之处。例如，我们自己的工作表明，海绵使用谷氨酸和GABA来刺激和抑制组织的收缩，就像在高等动物中一样。我们提出的研究计划侧重于确定细胞之间发生信号传递的区域(是否存在‘原突触’？)最终确定参与信号传递的新细胞在发育中和成年海绵中的哪里产生。

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.