RUI: Neural Regulation of Metamorphosis in a Gastropod Mollusc

RUI：腹足类软体动物变态的神经调节

• 批准号: 0110832
• 负责人: Anthony Pires
• 金额: $ 15.1万
• 依托单位: Dickinson College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0110832&HistoricalAwards=false
• 关键词: RUI; Neural; Regulation; Metamorphosis; Gastropod

Pires0110832AbstractMetamorphosis is a profoundly important transition in the life history of most animals. The passage from a larval to juvenile form entails destruction of some tissues, respecification of others and generation of new structures. In larvae of gastropod molluscs and in a diverse range of larvae from other phyla, metamorphosis is initiated by a chemical signal from the environment. The chemosensory induction of gastropod metamorphosis, its stereotyped behavioral context and the neuromuscular nature of some morphogenic movements, and the rapidity of morphological change all suggest pervasive control by the larval nervous system. However, very little is known of the mechanisms by which the nervous system can direct dramatic morphological change at the level of the entire organism. Dr. Pires will investigate the neural control of metamorphosis in the gastropod, Crepidula fornicata, focusing on neural signaling in the destruction of the larval velum. This ciliated swimming and feeding organ is precipitously shed by loss of adhesion among and between several types of velar cells within minutes after competent larvae come in contact with the natural cue that induces metamorphosis. The large ciliated cells that line the margin of the velum are the first to detach in metamorphosis, are electrically excitable, and have been shown in other gastropods to carry a synaptically-driven calcium-mediated action potential that causes arrest of ciliary beating. These cilia are arrested in C. fornicata and other gastropods in the moments before destruction of the velum visibly begins, yet no studies have investigated the mechanistic relationship between electrical activity in the velum and the loss of cell adhesion that occurs in metamorphosis. Previous work by Dr. Pires and others has implicated endogenous dopamine as a neuromodulator that potentiates metamorphosis, but its effects on signaling in the velum are unexplored. There is also evidence that hydrogen peroxide or other reactive oxygen species are generated in the metamophosing velum and can induce velar destruction if exogenously applied, but it is not known if reactive oxygen species have a necessary signaling role in a neural mechanism that mediates velar destruction in natural metamorphosis.Dr. Pires will exploit the large size and predictably fast metamorphosis of C. fornicata larvae, and take advantage of microsurgical methods that he developed for working with isolated velar tissues. Dr. Pires and his students will apply intracellular and extracellular electrophysiological techniques as well as pharmacological, histochemical and high-performance liquid chromatographic methods to analyze how neural signals effect a rapid loss of cell adhesion in the metamorphosing velum. This project affords undergraduate research students an unusual opportunity to engage in developmental neuroscience that cuts across several levels of biological organization. An important further training dimension of this project is that summer work will take place at the University of Washington's Friday Harbor Laboratories, where undergraduates will be immersed in a rich and exhilarating scientific community at a time when they will be making decisions about future research careers.

变态是大多数动物生活史上一次极其重要的转变。从幼虫到幼虫的过程中，需要破坏一些组织，重新指定其他组织，并产生新的结构。在腹足软体动物的幼虫和其他门的不同种类的幼虫中，变态是由来自环境的化学信号启动的。腹足类变态的化学感官诱导，其刻板的行为背景，一些形态发生运动的神经肌肉性质，以及形态变化的快速，都表明幼虫神经系统的普遍控制。然而，人们对神经系统在整个有机体水平上引导戏剧性形态变化的机制知之甚少。Pires博士将研究腹足类动物Crepidula forNicata变态的神经控制，重点是破坏幼虫膜的神经信号。这种有纤毛的游动和摄食器官在几种类型的角质细胞之间的粘附力丧失后，在几分钟内就会急剧脱落，因为合格的幼虫接触到诱导变态的自然线索。排列在膜边缘的大型纤毛细胞在变态过程中最先分离，是可电兴奋的，在其他腹足类动物中已被证明携带突触驱动的钙介导的动作电位，导致纤毛跳动停止。这些纤毛在绒毛虫和其他腹足类动物中被阻止在膜被明显破坏之前的瞬间，但还没有研究探讨膜中的电活动和变态过程中发生的细胞黏附丧失之间的机制关系。Pires博士和其他人之前的工作表明，内源性多巴胺是一种神经调节剂，可以加强变态，但它对胎膜信号的影响尚不清楚。也有证据表明，过氧化氢或其他活性氧物种在变态膜中产生，如果外源应用，可以诱导膜破坏，但尚不清楚活性氧物种是否在介导自然变态过程中膜破坏的神经机制中具有必要的信号作用。皮雷斯将利用穹隆隐翅虫幼虫的巨大体型和可预见的快速变态，并利用他为处理分离的角质组织而开发的显微外科方法。皮雷斯博士和他的学生将应用细胞内和细胞外的电生理技术，以及药理学、组织化学和高效液相色谱方法，分析神经信号如何影响变性膜中细胞黏附的快速丧失。这个项目为本科生提供了一个不同寻常的机会来从事跨越生物组织的几个层次的发展神经科学。该项目的一个重要的进一步培训方面是，暑期工作将在华盛顿大学的星期五港湾实验室进行，在那里，本科生将沉浸在一个丰富而令人振奋的科学社区中，他们将对未来的研究职业做出决定。