RUI - Nitric Oxide Inhibition of Metamorphosis in a Marine Snail

在发育过程中，神经系统的细胞经历了生长和增殖期，通常会产生过多的细胞。当细胞连接到它们的成体环路时，多余的细胞和临时结构中的细胞会死亡，并通过一个自然发生的过程被移除，这个过程称为细胞凋亡。这一过程在一定程度上受到可扩散的信号分子的调节，这些分子在成年人中也充当神经递质的角色。神经递质是神经细胞用来相互交流的一种小化合物。其中一个这样的分子是可扩散的气体，一氧化氮。一旦进入细胞，一氧化氮与其目标分子的相互作用就会引发一连串的生化事件。尽管一氧化氮与调节细胞增殖和细胞凋亡有关，但对其在神经系统发育调控中的作用却知之甚少。莱斯博士的实验室之前的研究表明，一氧化氮是一种海洋蜗牛变态的天然抑制因子。在这个过程中，大脑中的一群神经元，即所谓的心尖神经节消失。Leise博士和Hens博士假设这个神经节的消失是细胞凋亡的结果。他们将使用组织化学测试来寻找顶端神经节细胞中是否存在在细胞凋亡过程中形成的DNA片段。他们还将进行相关的药理学和解剖学研究，以确定一氧化氮是否调节这一过程。他们将研究神经细胞增殖与变态的关系，并将确定一氧化氮是否也控制新神经元的诞生。最后，他们将使用分子和免疫细胞化学方法来识别胚胎大脑中产生一氧化氮的酶的区域，并确定这种酶的产生在发育过程中何时停止，从而确定一氧化氮的产生。一氧化氮作为一种神经递质自然存在于成年人的大脑中，它在成年人大脑功能中的重要性已被广泛接受。然而，人们对这种重要分子在胚胎发育中的作用知之甚少。这些研究将进一步加深我们对胚胎大脑中一氧化氮及其对神经发育调控的重要性的理解。

During development, the cells of the nervous system go through periods of growth and proliferation and are often produced in excess. As cells become connected into their adult circuits, excess cells and cells in temporary structures die and are removed by a naturally occurring process called apoptosis. This process is regulated, in part, by diffusible signaling molecules that also act as neurotransmitters in adults. Neurotransmitters are small compounds that nerve cells use to communicate with each other. One such molecule is the diffusible gas, nitric oxide. Once inside a cell, the interaction of nitric oxide with its target molecule sets off a cascade of biochemical events. While nitric oxide has been implicated in regulating both cellular proliferation and apoptosis, little information exists about its role in the regulation of nervous system development. Previous work in Dr. Leise's laboratory has indicated that nitric oxide acts as a natural inhibitor of metamorphosis in a species of marine snail. During this process, one cluster of neurons in the brain, the so-called apical ganglion, disappears. Drs. Leise and Hens hypothesize that the disappearance of this ganglion is a result of apoptosis. They will use a histochemical test to look in apical ganglion cells for the presence of DNA fragments which form during apoptosis. They will also conduct related pharmacological and anatomical investigations to determine if nitric oxide regulates this process. They will investigate the relationship of nerve cell proliferation to metamorphosis and will determine if nitric oxide also controls the birth of new neurons. Finally, they will use molecular and immunocytochemical methods to identify regions of the embryonic brain that produce the enzyme that generates nitric oxide and determine when the production of the enzyme, and thus nitric oxide, cease during development. Nitric oxide occurs naturally as a neurotransmitter in the brains of adult humans, and its importance in the function of the adult brain is widely accepted. However, little is known about the role of this important molecule in embryonic development. These studies will further our understanding of nitric oxide in the embryonic brain and its importance for the regulation of neural development.