Genetic Analysis of C. elegans Predator Avoidance

描述(申请人提供)：所有生物体都具有检测和应对环境中威胁的内在能力，但其潜在的分子机制却知之甚少。对这一过程的完整理解需要对潜在神经回路的知识，以及测量和干扰它们活动的能力，最重要的是。这在复杂的脊椎动物电路中是很难获得的。然而，无脊椎动物的电路具有明确的神经解剖学和量化行为，是破译指导复杂输出的潜在机械的理想位置。这项提议旨在了解无脊椎动物大脑模型中编码威胁反应(行为和生理)的神经机制。线虫，秀丽线虫，提供了一个独特的机会，使用多尺度的方法来分析调节复杂行为的基因、细胞和电路。Chalasani实验室开发了一种新的威胁行为模型，利用线虫和另一种线虫Pristionchus pacphaus之间的相互作用。一只饥饿的Pristionchus将在30分钟内攻击并吞噬线虫。反过来，线虫又会避开普里斯库和它的分泌物。除了这种行为反应，线虫还会在暴露于Pristionchus时激活线粒体应激。提出的研究计划的目标是确定在这个模型系统中调节回避行为的细胞和分子机制。已经确定，一种包括三个新的感觉神经元(ASJ、ASK和ASI)的新型神经回路驱动回避行为和生理应激反应。具体目标1将确定这种神经元回路以及相关的神经递质和受体，这些神经递质和受体调节捕食者回避和线粒体应激反应。AIM 2将优化一个自动行为平台，以快速分析大量蠕虫的行为，并对影响回避行为的基因进行大规模筛选。一项试点筛查发现了4个有趣的基因，它们是调节回避行为所必需的。这些包括TRPV通道(可能是Pristionchus传感机制的一部分)、谷氨酸转运体、5-羟色胺生物合成酶和5-羟色胺再摄取转运体。AIM 3专注于从基因筛查中验证这些和其他候选者。这些研究将阐明神经回路如何在突触、神经回路和整个生物体的水平上处理有关环境威胁的信息。此外，我们将确定神经电路如何整合谷氨酸和5-羟色胺信号以产生复杂行为的基本原理和保守机制。

DESCRIPTION (provided by applicant): All organisms possess an intrinsic ability to detect and respond to threats in their environments, but the underlying molecular mechanisms are poorly understood. A complete understanding of this process requires knowledge of the underlying neural circuits along with an ability to measure and, most importantly, perturb their activity. This is difficult to obtain in complex vertebrate circuits. However, invertebrate circuit with their well-defined neuroanatomy and quantitative behaviors are ideally placed to decipher the underlying machinery guiding complex outputs. This proposal aims to understand the neural mechanisms that code threat responses (both behavioral and physiological) in an invertebrate brain model. The nematode, Caenorhabditis elegans, provides a unique opportunity to analyze, using a multi- scale approach, genes, cells and circuits that regulate complex behaviors. The Chalasani lab has developed a novel model of threat behaviors using the interactions between C. elegans and a second nematode, Pristionchus pacificus. A starving Pristionchus will attack and devour C. elegans in 30 minutes. C. elegans in turn, will avoid both Pristionchus and its secretions. Apart from this behavioral response, C. elegans also activates mitochondrial stress upon exposure to Pristionchus. The goals of the proposed research program are to define the cellular and molecular mechanisms regulating avoidance behavior in this model system. It has already been determined that a novel neural circuit including three new sensory neurons (ASJ, ASK and ASI) drive avoidance behavior and physiological stress responses. Specific aim 1 will identify this neuronal circuit and the associated neurotransmitters and receptors that regulate predator avoidance and mitochondrial stress responses. Aim 2 will optimize an automated behavioral platform to rapidly analyze behaviors from large numbers of worms and perform a large screen for genes affecting avoidance behavior. A pilot screen has identified 4 interesting genes as required for regulating avoidance behavior. These include a TRPV channel (might be part of the Pristionchus sensing machinery), glutamate transporters and serotonin biosynthesis enzyme and serotonin re-uptake transporter. Aim 3 is focused on validating these and other candidates from the genetic screen. These studies will clarify how neural circuits process information about environmental threats at the level of synapses, neural circuits and whole organisms. Moreover, we will identify basic principles and conserved mechanisms of how neural circuits integrate glutamate and serotonin signaling to generate complex behaviors.