Ecology of host/parasite interactions

宿主/寄生虫相互作用的生态学

• 批准号: RGPIN-2018-05067
• 负责人: Goater, Cameron
• 金额: $ 2.4万
• 依托单位: University of Lethbridge
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=713495
• 关键词: Ecology; host; parasite; interactions

All parasites must solve the problem of transmitting infective stages into new hosts. Not surprisingly, transmission rate' is a fundamental parameter in epidemiological models that describe parasite population dynamics, including for problem parasites of humans, domestic animals, and wildlife. The long-term goal of my research program is to understand the factors that determine variation in transmission rates for parasites of wild animals. Many parasites have complex life-cycles, the completion of which requires the transmission of infective stages between a sequence of obligate hosts. Some solutions to solving the problem of transmission between hosts are spectacular in their expression. Ants infected with larvae of the fluke, Dicrocoelium, are chauffeured from their nests to adjacent flowers, onto which they remain attached with their mandibles during the evening hours. When temperature warms the next day, they detach and return to their nests. Attachment facilitates transmission of the larvae into grazing mammals. This cycle of attachment/detachment continues for weeks at our study sites in Cypress Hills Park, Alberta where the fluke has been introduced. In this proposal, my students and I combine genomics tools, imaging tools, and behaviour assays to determine if zombie-ism requires physical manipulation of structures in the brain that control mandibular muscles, or the secretion of gene products that lead to neuromodulation, or both. One possibility is that attachment/detachment behaviours are associated with the upregulation of particular gene products that are temperature-dependent. Understanding the mechanisms leading to the cycle of attachment/detachment in infected ants is a key step towards understanding the pervasive phenomenon of host phenotype alteration by parasites, which extends to humans infected with Toxoplasma, and wildlife/pets infected with rabies virus. In a second model system, we manipulate infection dose to test hypotheses regarding the factors underlying variation in rates of parasite transmission. My students and I will evaluate how rates of transmission are influenced by the diversity and structure of host communities. In our current age of ever-increasing changes in animal biodiversity, there is an increased recognition that features such as biodiversity loss and gain have strong effects on rates of transmission, including for diseases of humans. But the host biodiversity vs. transmission association is contentious because so few systems are amenable to the manipulation of both exposure dose and biodiversity. In our model minnow/snail/trematode interaction, we will combine exposure trials into experimental communities of fish and snails in lab and mesocosm settings to test whether introductions of non-native snails and fish can explain the marked changes in rates of transmission we have observed in local waterbodies in southern Alberta.

所有寄生虫都必须解决将感染阶段传播到新宿主的问题。毫不奇怪，“传播率”是描述寄生虫种群动态的流行病学模型中的一个基本参数，包括人类、家畜和野生动物的问题寄生虫。我的研究计划的长期目标是了解决定野生动物寄生虫传播率变化的因素。 许多寄生虫具有复杂的生命周期，其完成需要在一系列专性宿主之间传播感染阶段。解决主机之间传输问题的一些解决方案在表达上是壮观的。感染了吸虫幼虫的蚂蚁，被从巢穴运到邻近的花朵上，在晚上的时间里，它们仍然用下颌附着在花朵上。当第二天气温变暖时，它们会离开并返回巢穴。附着有利于幼虫传播到食草哺乳动物。在我们位于阿尔伯塔的柏树山公园的研究地点，这种附着/分离的循环持续了数周，那里已经引入了吸虫。在这个提议中，我和我的学生联合收割机将基因组学工具、成像工具和行为分析结合起来，以确定是否需要对控制下颌肌的大脑结构进行物理操作，或者分泌导致神经调节的基因产物，或者两者兼而有之。一种可能性是附着/分离行为与温度依赖性的特定基因产物的上调有关。了解感染蚂蚁的附着/脱离循环机制是了解寄生虫改变宿主表型的普遍现象的关键一步，寄生虫可扩展到感染弓形虫的人类和感染狂犬病病毒的野生动物/宠物。 在第二个模型系统中，我们操纵感染剂量，以测试假设的寄生虫传播率的变化有关的因素。我和我的学生将评估传播率如何受到宿主社区的多样性和结构的影响。在我们这个动物生物多样性不断变化的时代，人们越来越认识到，生物多样性的丧失和获得等特征对传播率，包括人类疾病的传播率有很大影响。但是宿主生物多样性与传播的关系是有争议的，因为很少有系统能够同时操纵暴露剂量和生物多样性。在我们的模型小鱼/蜗牛/吸虫的相互作用，我们将结合联合收割机暴露试验到实验室和围隔环境中的鱼类和蜗牛的实验社区，以测试是否引入非本地蜗牛和鱼类可以解释我们在阿尔伯塔南部的当地水体中观察到的传播率的显着变化。