GSE68176
Gene expression during biting behavior in zombie ants reflects the complexity of fungal pathogenic manipulation of ants
The biting behavior observed in Carpenter ants infected by the specialized fungus Ophiocordyceps unilateralis s.l. is an example of a complex host behavioral manipulation by parasite. Though parasitic manipulation of host behavior is generally assumed to be due to the parasite's gene expression, few studies have set out to test this. We experimentally infected Carpenter ants to collect tissue from both parasite and host during the time period when manipulated biting behavior is experienced. Upon observation of synchronized biting, samples were collected and subjected to RNA-Seq analyses. We also sequenced and annotated the O. unilateralis s.l. genome as a reference for the fungal reads. Our mixed transcriptomics approach, together with a comparative genomics study, shows that the majority of the fungal genes that are up-regulated during manipulated biting behavior are unique to the O. unilateralis s.l. genome. This study furthermore reveals that the fungal parasite might be regulating immune- and neuronal stress responses in the host during manipulated biting, as well as impairing its chemosensory communication and causing apoptosis. Moreover, we found genes up-regulated during manipulation that putatively encode for proteins with reported effects on behavioral outputs, proteins involved in various neuropathologies, and proteins involved in the biosynthesis of secondary metabolites such as alkaloids. Overall design: Analysis of mixed transcriptomes during host-parasite interactions. In triplicates, we examinated the gene expression of ant host (Camponotus castaneus) and fungal parasite (Ophiocordyceps unilateralis s.l.) in infected ant heads during and after manipulated biting behavior. As controls, we used healthy ants and fungal cultures grown in shaking flasks with Grace's insect medium supplemented with 10% FBS.