Mechanosensory Behaviors of Skin-Penetrating Parasitic Nematodes

项目摘要/摘要 这项研究计划的总体目标是表征穿透皮肤的机械感觉行为。 寄生线虫，能够定位和入侵寄主生物体。穿透性寄生虫 线虫，包括线虫斯特氏线虫，感染着全世界近10亿人， 是被忽视的热带病的主要来源。通常在土壤中发现的是具感染性的三分之一- 阶段幼虫(IL3)；生活在土壤中的iL3参与了各种被认为增加可能性的行为 主机联系人的数量。该假说认为，严重链球菌对机械刺激的感觉和随之而来的 行为反应是寻找宿主不可或缺的一部分，皮肤渗透长期以来一直被认为是不可或缺的，但实际上 没有经过测试。此外，潜在的机械转导通路和机械感觉神经元 电路是未知的。这项提案中的实验将解决这一知识差距。第一套 实验将表征SstercoralisiL3s对类似于 由人类在土壤上行走产生的。具体地说，振动吸引和促进iL3的程度 促进寄主依附的行为，包括NICTICATION，将被详细研究。同时，一个深入的 将使用人体皮肤对皮肤渗透的行为范式进行分析。建议数 实验还将确定人类皮肤特有的僵硬或质地是否会促进皮肤 穿透力。暴露在振动和宿主皮肤中引起的行为也将在其他物种中进行研究 寄生线虫--穿透皮肤的人体寄生钩虫--锡兰钩虫和 被动摄取小鼠多回寄生虫和自由生活线虫线虫 用于识别穿透皮肤的线虫的物种特定行为适应。此外，这项工作 将通过使用一种新的方法识别作为寻找宿主和皮肤穿透基础的机械感觉基因和回路 多种方法的结合：编码预测机械感受器的基因的转录报告 鉴定可能的机械感觉神经元；利用CRISPR/Cas9对相同基因进行靶向突变 随后是对行为的跟踪；使用 组胺门控氯离子通道HisCl1随后进行行为学研究；以及脑内钙瞬变的成像 相同的神经元在刺激下。综上所述，本提案中的工作将识别机械感觉行为 它们是穿透皮肤的寄生线虫所特有的，这些线虫能使宿主接触和入侵。现有 治疗弓形虫病不能防止再次感染；这项工作可能会通过揭示 开发预防性驱虫药和局部乳膏的新分子靶点。

PROJECT SUMMARY/ABSTRACT The overall goal of this research proposal is to characterize the mechanosensory behaviors of skin-penetrating parasitic nematodes that enable the location and invasion of a host organism. Skin-penetrating parasitic nematodes, including the threadworm Strongyloides stercoralis, infect nearly one billion people worldwide and are major sources of neglected tropical disease. S. stercoralis is normally found in the soil as infective third- stage larvae (iL3s); soil-dwelling iL3s engage in a variety of behaviors that are thought to increase the likelihood of host contact. The hypothesis that the sensation of mechanical stimuli by S. stercoralis iL3s and the ensuing behavioral response are together integral to host seeking and skin penetration has long been postulated but has not been tested. Furthermore, the underlying mechanotransduction pathways and mechanosensory neuronal circuits are not known. The experiments in this proposal will address this gap in knowledge. The first set of experiments will characterize the behavioral response of S. stercoralis iL3s to vibrations resembling those generated by humans walking on soil. Specifically, the extent to which vibration attracts iL3s and promotes behaviors that facilitate host attachment, including nictation, will be examined in detail. In parallel, an in-depth analysis of the behavioral paradigm of skin penetration will be conducted using human skin. The proposed experiments will also determine whether the stiffness or texture that is particular to human skin promotes skin penetration. Behaviors induced by exposure to vibration and host skin will also be studied in other species of parasitic nematodes – the skin-penetrating human-parasitic hookworm Ancylostoma ceylanicum and the passively ingested murine parasite Heligmosomoides polygyrus – and the free-living nematode Caenorhabditis elegans to identify species-specific behavioral adaptations of skin-penetrating nematodes. Additionally, this work will identify the mechanosensory genes and circuits that underlie host seeking and skin penetration by using a combination of approaches: transcriptional reporters for genes that encode predicted mechanoreceptors to identify putative mechanosensory neurons; targeted mutagenesis of the same genes with CRISPR/Cas9 followed by tracking of behavior; chemogenetic silencing of potential mechanosensory neurons using the histamine-gated chloride channel HisCl1 followed by behavioral studies; and imaging of calcium transients in the same neurons upon stimulation. Together, the work in this proposal will identify the mechanosensory behaviors that are specific to skin-penetrating parasitic nematodes that enable host contact and host invasion. Existing therapeutics for strongyloidiasis do not prevent re-infection; this work may alleviate the problem by uncovering novel molecular targets for the development of preventive anthelmintic drugs and topical creams.