Project description:Parasites with complex life cycles often manipulate the phenotype of their intermediate hosts to increase the probability of transmission to their definitive hosts. Infection with Anomotaenia brevis, a cestode that uses Temnothorax nylanderi ants as intermediate hosts, leads to a multiple-fold extension of host lifespan and to changes in behaviour, morphology and colouration. The mechanisms behind these changes are unknown, as is whether the increased longevity is achieved through parasite manipulation. Here, we demonstrate that the parasite releases proteins into its host with functions that might explain the observed changes. These parasitic proteins make up a substantial portion of the proteome of the hosts' haemolymph, and thioredoxin peroxidase and superoxide dismutase, two antioxidants, exhibited the highest abundances among them. The largest part of the secreted proteins could not be annotated, indicating they are either novel or severely altered during recent coevolution to function in host manipulation. We also detected shifts in the hosts' proteome with infection, in particular an overabundance of vitellogenin-like A in infected ants, a protein that regulates division of labour in Temnothorax ants, which could explain the observed behavioural changes. Our results thus suggest two different strategies that might be employed by this parasite to manipulate its host: secreting proteins with immediate influence on the host's phenotype and altering the host's translational activity. Our findings highlight the intricate molecular interplay required to influence the phenotype of a host and point to potential signalling pathways and genes involved in parasite-host communication.
Project description: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.
Project description:Female larvae of the honeybee (Apis mellifera) develop into either queens or workers depending on nutrition during larval development. This nutritional stimulus triggers different developmental trajectories, resulting in adults that differ in physiology, behaviour and life-span. To understand how these developmental trajectories are established we have undertaken a comprehensive analysis of differential gene expression throughout larval development.
Project description:Female larvae of the honeybee (Apis mellifera) develop into either queens or workers depending on nutrition during larval development. This nutritional stimulus triggers different developmental trajectories, resulting in adults that differ in physiology, behaviour and life-span. To understand how these developmental trajectories are established we have undertaken a comprehensive analysis of differential gene expression throughout larval development.
Project description:The daily cycle of night and day affects the behaviour and physiology of almost all living things. At the molecular level, many genes show daily changes in expression levels. To determine whether changes in transcript abundance occur in wood forming tissues of Eucalyptus trees we used a cDNA microarray to examine gene expression levels at roughly four hour intervals throughout the day.