| NSF Org: |
IOS Division Of Integrative Organismal Systems |
| Recipient: |
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| Initial Amendment Date: | February 10, 2016 |
| Latest Amendment Date: | February 10, 2016 |
| Award Number: | 1558062 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Mamta Rawat
mrawat@nsf.gov (703)292-7265 IOS Division Of Integrative Organismal Systems BIO Directorate for Biological Sciences |
| Start Date: | February 15, 2016 |
| End Date: | January 31, 2019 (Estimated) |
| Total Intended Award Amount: | $547,000.00 |
| Total Awarded Amount to Date: | $547,000.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
201 OLD MAIN UNIVERSITY PARK PA US 16802-1503 (814)865-1372 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
110 Technology Center Bld University Park PA US 16802-7000 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Symbiosis Infection & Immunity |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.074 |
ABSTRACT
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.
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
A dramatic phenomenon in nature is the ability of fungal parasites to control ants climb vegetation to bite hard into leaves and twigs before being killed. This gruesome mind control is adaptive for the fungus because it must grow from the dead body of the ant and the death grip behavior it induced means it has secured a safe place to grow and ultimately launch spores from that infect other ants. This is the zombie ant system.
In our NSF project we set out to understand how this happens. We were particularly interested in the difference between fungi, which are microscopic and the ants that they control which are not only multicellular animals but occur in large cohesive societies. We wanted to know how the organism without the brain controls the one with the brain. We took a multidisciplinary approach that integrated behavioral studies, micro-scale histology with Serial Block Face SEM, standard SEM, immunofluorescence confocal microscopy, metabolomics and transcriptomics. We found that at the time of manipulation, when the ant is manipulated to bite, the fungal parasite has arranged itself into a complex 3D network that surrounds and penetrates the host cells. Surprisingly the fungal cells do not enter the brain of the ant. We did find however the brain of zombie ants are very different to those of healthy ants. We found that the fungus injects specialized compounds into the brain of the ant and the brain has a very distinct chemical signatures, dominated by neuromodulator changes and oxidative reductive processes. We suggest that the zombie ant fungus manipulates its ant host from the periphery, carefully manipulating the muscles while preserving the brain intact, presumably because that is necessary for the full successful behavioral manipulation. Zombie ants are apparently like zombies in human fiction- the brain is critical.
Last Modified: 03/19/2019
Modified by: David Hughes
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