Zombie Ants: Towards a Mechanistic Understanding of the Precise Control of Animal Behavior by a Microbial Parasite

自然界中共生现象最复杂的例子之一是微生物对动物行为的精确操纵。蛇孢菌是一种感染僵尸蚂蚁的真菌。 工蚁被成千上万的真菌细胞感染后，会离开殖民地，然后用它们的下颚附着在那些悬挂在蚁群足迹上的植物上死去。在那里，真菌利用死蚂蚁的尸体产生孢子，感染其他蚂蚁。考虑到一个没有大脑的生物体控制着一个有大脑的生物体的行为，这种操纵是复杂而壮观的。在这个项目中，研究小组将使用一种综合的方法来研究真菌是如何将蚂蚁从群体中的生产成员变成“蚂蚁衣服上的真菌”的？".该项目将使用基因表达，代谢和组织结构的测量来研究真菌如何在感染的3周内有效地控制蚂蚁。 这项工作将为寄生虫的性质提供许多一般性的见解，并可能具有更广泛的社会意义，因为这些真菌是具有医学相关性的小分子的重要来源。这项工作与NSF提高科学素养的更广泛的使命有关，因为僵尸蚂蚁系统已被证明是传达自然系统优雅和美丽的非常有用的工具。微生物如何控制动物的中枢神经系统？动物与微生物有着密切的联系，从互惠共生到寄生共生。在某些情况下，动物的微生物寄生虫已经进化到以增强寄生虫传播的方式控制动物行为。僵尸蚂蚁就是一个突出的例子。 在这个系统中，一种真菌寄生虫（Ophiocorphiumunilateralis）已经进化出了对它感染的蚂蚁的精确行为控制。感染O.在一天中的精确时间，单边虫从它们的殖民地移动到森林树叶上的高度特定的位置，在那里它们在死亡前咬进植被。这种行为的改变为最终从蚂蚁尸体上长出的真菌茎释放孢子提供了一个平台。这个引人注目的系统涉及一个生命王国（真菌）中的有机体控制另一个生命王国（动物王国）中有机体的行为。 一个没有大脑的有机体如何控制一个有大脑的有机体的行为？ 研究人员将使用时间序列感染研究来测量寄生虫及其宿主的化学变化来解决这个问题。 通过使用三种不同但互补的工具（连续块面扫描电子显微镜，代谢组学和转录组学）来检查这些随时间的变化，研究人员希望了解这些行为变化的基础。

One of the most complex examples of symbiosis in nature is the precise manipulation of animal behavior by a microbe. Ophiocordyceps is a fungus that infects zombie ants. Infection of ant workers by thousands of these fungal cells causes the workers to leave the colony and die attached by their mandibles to plants that overhang the trails of ant colonies. There the fungus uses the dead ant bodies to produce spores that infect other ants. The manipulation is complex and spectacular given the fact that an organism without a brain controls the behavior of one with a brain. In this project the research team will use an integrative approach to ask how fungi change ants from being productive members of their colony to "fungi in ant's clothing?". The project will use measurement of gene expression, metabolism and tissue structure to ask how, during the 3 week period of infection, the fungi effectively take control of the ant. This work will provide many general insights into the nature of parasitism and may have broader societal relevance because these fungi are known to be important sources of small molecules with medical relevance. The work is relevant to the broader mission of NSF to increase scientific literacy as the zombie ant system has been shown to be a very useful tool for communicating the elegance and beauty of natural systems. How can a microbe control the central nervous system of an animal? Animals are intimately associated with microbes that span the symbiotic spectrum from mutualism to parasitism. In some cases, microbial parasites of animals have evolved to control animal behavior in ways that enhance parasite transmission. The zombie ants represent one prominent example. In this system a fungal parasite (Ophiocordyceps unilateralis) has evolved a precise level of behavioral control over the ants it infects. Worker ants infected by O. unilateralis move out from their colonies at precise times of day to highly specific locations on leaves in forests, where they bite into vegetation before dying. This altered behavior provides a platform for the eventual release of spores from a long fungal stalk that grows from the cadaver of the ant. This striking system involves an organism in one kingdom of life (Fungi) that controls the behavior of an organism in another (Animalia). How does an organism without a brain control the behavior of one with a brain? The investigators will address this using time series infectionstudies to measure chemical changes in both the parasite and its host. By using three different but complementary tools (serial block face scanning electron microscopy, metabolomics and transcriptomics) to examine these changes across time, the investigators hope to understand the basis of these behavioral changes.