The molecular basis and evolution of host manipulation by nematomorph parasites

线形寄生虫操纵宿主的分子基础和进化

• 批准号: 2599069
• 金额: --
• 依托单位: University of Bath
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2599069
• 关键词: molecular; basis; evolution; host; manipulation

The Nematomorpha, commonly known as horsehair worms, comprise one of three fully parasitic animal phyla. Nematomorphs are parasitic worms of invertebrates, which infect and manipulate the behaviour of their definitive arthropod host (e.g. crickets) to 'commit suicide' by jumping into water. They do this to reach an aquatic environment, which they require to complete their life cycle. Although observations of this behaviour are relatively common, the underlying mechanism of this behavioural manipulation at a molecular and genetic level remains understudied. Therefore, the overall aims of this project are to investigate the underlying molecular mechanism involved in this behavioural manipulation, how this mechanism evolved, and the diversity of nematomorphs within the UK, and potentially internationally, thus increasing our knowledge of this understudied area.The initial objectives of this project involve; culturing the nematomorph life cycle in the laboratory whilst maintaining stocks of the definitive (cricket) and paratenic (freshwater snails) hosts, and designing a behavioural assay for analysis of experimental manipulation. The methodology for this project involves field, laboratory and computational components. Field aspects will involve collecting free-living adult worms, cysts or larvae from aquatic environments, or collecting the host (e.g. crickets), which would be placed in water for the emergence of worms. Specimens will be collected from various locations across the UK, with potential collection from the US and Japan. All specimens would be identified to species level, where applicable, via microscopy or molecular techniques. Genomic and genetic investigation, and phylogenetic analyses would be used to investigate the diversity of nematomorphs in the UK, with potential comparisons between locations. Laboratory components will involve establishing and maintaining a culture of nematomorphs, and colonies of their definitive and paratenic hosts in the laboratory. This system will be used for collection of tissue or secretions from the various life cycle stages of the parasite, and the infected and uninfected host, which will enable RNA, protein and small RNA extraction and identification via mass spectrometry or sequencing. Isolated secretions will be used in behavioural assays of the insect host to investigate the ability of each secretion to alter host behaviour. Finally, this project will use bioinformatics to investigate which genes, proteins, and small RNAs are expressed and the level of expression. These expression profiles can then be compared between the life cycle stages of the worm and infection status of the host. This will aid in investigating how this behavioural manipulation evolved, e.g. if a given gene, protein or small RNA associated with host infection is present or expressed throughout the nematomorph life cycle, it could imply said gene, protein or small RNA is essential for nematomorph functioning and accidently had the given behavioural effect, which being beneficial for the worm, evolved to exploit this. Conversely, if the given gene, protein or small RNA is only present or expressed during the stages of the worm associated with host infection, it could imply this mechanism evolved in response to being inside the host as a method to re-enter an aquatic environment to complete their life cycle.

线虫纲，通常被称为马毛蠕虫，包括三个完全寄生的动物门之一。线虫是无脊椎动物的寄生蠕虫，它们感染并操纵其最终节肢动物宿主（例如蟋蟀）的行为，通过跳入水中“自杀”。它们这样做是为了到达一个水生环境，这是它们完成生命周期所必需的。虽然这种行为的观察是比较常见的，这种行为操纵在分子和遗传水平上的潜在机制仍然研究不足。因此，本项目的总体目标是研究这种行为操纵所涉及的潜在分子机制，这种机制是如何演变的，以及在英国和潜在的国际上的线虫形态的多样性，从而增加我们对这一研究不足的领域的了解。在实验室中培养线虫生命周期，同时保持最终（蟋蟀）和寄生虫（淡水蜗牛）宿主的库存，并设计一种行为测定法用于分析实验操作。该项目的方法包括实地、实验室和计算部分。田间方面将涉及从水生环境中收集自由生活的成虫、包囊或幼虫，或收集宿主（如蟋蟀），将其置于水中以使蠕虫出现。标本将从英国各地收集，可能从美国和日本收集。所有标本都将通过显微镜或分子技术鉴定到物种水平（如适用）。基因组和遗传调查以及系统发育分析将用于调查英国线虫的多样性，并在不同地点之间进行潜在的比较。实验室组成部分将涉及建立和维持线虫的培养，以及在实验室中建立和维持其终末宿主和寄生宿主的菌落。该系统将用于收集寄生虫不同生命周期阶段的组织或分泌物，以及受感染和未受感染的宿主，这将使RNA，蛋白质和小RNA提取和鉴定通过质谱或测序。分离的分泌物将用于昆虫宿主的行为测定，以研究每种分泌物改变宿主行为的能力。最后，本项目将使用生物信息学来研究哪些基因、蛋白质和小RNA被表达以及表达水平。这些表达谱可以在蠕虫的生命周期阶段和宿主的感染状态之间进行比较。这将有助于研究这种行为操纵是如何进化的，例如，如果与宿主感染相关的给定基因、蛋白质或小RNA在整个线虫生命周期中存在或表达，则可能意味着所述基因、蛋白质或小RNA对于线虫形态的功能至关重要，并且意外地具有给定的行为效应，这对蠕虫有利，进化以利用这一点。相反，如果给定的基因、蛋白质或小RNA仅在与宿主感染相关的蠕虫阶段存在或表达，则可能意味着这种机制是为了响应宿主内部的变化而进化的，作为重新进入水生环境以完成其生命周期的方法。