Biology subjects

Will, I.

Publications and source records attributed to Will, I..

7 recordsLinked to original sources

bioRxiv2025

Coinfections dampen the effects of temperature on host-parasite interactions

Coinfections by multiple parasite species are widespread and modify disease outcomes. To what degree other forms of ecological complexity, such as environmental change, influence the impacts of coinfecting parasites on disease remains unclear. We exposed nematodes (Caenorhabditis elegans) to naturally coinfecting parasites (Leucobacter celer and musarum) at temperatures across the hosts thermal range. While we found that host mortality varied widely with temperature during single infections, coinfections buffered hosts against temperature-mediated variation via ongoing parasite competition. We extended our experiments with mathematical models indicating that changing virulence, rather than transmission, most plausibly underpins temperature-dependent host mortality. At moderate, but not extreme temperatures, we found coinfection continued to dampen mortality outcomes due to another source of host variation, genotypic susceptibility. Coinfection may provide a stabilizing effect on disease in a warming world - but this effect can falter when hosts are faced with multiple stressors.

ecology↗

bioRxiv2024

Pathogenic fungus expresses effector proteins in combination with a symbiotic virus to behaviourally manipulate housefly hosts

Host manipulation by pathogens and parasites is a widespread phenomenon, but the molecular mechanisms are poorly understood. We investigated the summiting disease caused by the fungus Entomophthora muscae in houseflies, where infected flies climb to elevated positions and die, releasing infectious conidia. We performed dual-RNA sequencing of fly heads at different time points and identified candidate genes from both the host and the pathogen that may be involved in this summiting phenotype. Surprisingly, we also detected a high abundance of a novel positive sense single-stranded (+ss-RNA iflavirus in infected fly heads. We show that the virus load increases over time and shows signs of accumulation in fly heads and thoraces. We also reveal predicted interactions between fungal secreted proteins and insect host proteins related to neurological and immune functions, suggesting a possible role of these proteins in host manipulation. Furthermore, we find that E. muscae encodes a homologue of ecdysteroid UDP-glucosyltransferase (egt), a gene that has been implicated in host manipulation by other pathogens. Our study reveals a complex interplay between a fungus, a virus and a fly, and suggests that convergent evolution of egt for host manipulation mechanisms may occur in different pathogens.

evolutionary biology↗

bioRxiv2023

Metabolomic characterization of behaviorally manipulated ants with multiomic data integration

Camponotus floridanus ants show altered behaviors followed by a fatal summiting phenotype when infected with manipulating Ophiocordyceps camponoti-floridani fungi. Host summiting as a strategy to increase transmission is also observed with parasite taxa beyond fungi, including aquatic and terrestrial helminths and baculoviruses. The drastic phenotypic changes can sometimes reflect significant physiological changes within host cells that span molecular levels from metabolites to nucleic acids. Nevertheless, the underlying mechanisms still need to be fully characterized. To investigate the small molecules producing summiting behavior, we infected C. floridanus ants with O. camponoti-floridani and sampled their heads for LC-MS/MS when we observed the characteristic summiting phenotype. We link this metabolomic data with our previous genomic and transcriptomic data to propose mechanisms that underlie manipulated summiting behavior in "zombie ants." This "multiomic" evidence points toward the dysregulation of neurotransmitter levels and neuronal signaling. We propose that these processes are altered during infection and manipulation based on 1) differential expression of neurotransmitter synthesis and receptor genes, 2) altered abundance of metabolites and neurotransmitters (or their precursors) with known behavioral effects in ants and other insects, and 3) possible suppression of a connected immunity pathway. We additionally report signals for metabolic activity during manipulation related to primary metabolism, detoxification, and anti-stress protectants.

bioinformatics↗

bioRxiv2023

Using RNASeq to investigate the involvement of the Ophiocordyceps clock in ant host infection and behavioral manipulation

IntroductionParasites can modify host behavior to ensure their own growth and transmission. Multiple species of the fungi Ophiocordyceps infect ants, but in a species-specific manner; one fungal species co-evolved to successfully modify the behavior of one ant species. However, several characteristics of the behavioral modification seem to be similar across different Ophiocordyceps-ant systems, including a preference for the time of the day for manipulating host behavior. In this study, we explored the various mechanisms via which the circadian clock of Ophiocordyceps might be playing a role in modifying host behavior. We studied O. camponoti-floridani that modifies the behavior of its ant host Camponotus floridanus. To separate the role of the clock in behavior manipulation, from its role in growth and survival, we compared the daily gene expression profile of O. camponoti-floridani to a generalist, non-manipulating fungal parasite, Beauveria bassiana, which also successfully infects the same ant host. ResultsMajority of the 24h rhythmic O. camponoti-floridani genes show peak expression before or at the transitions between light and dark. Rhythmic genes in O. camponoti-floridani, for which B. bassiana lacks an ortholog, were overrepresented for enterotoxin genes. Around half of all genes that show 24h rhythms in either O. camponoti-floridani or B. bassiana showed a consistent difference in their temporal pattern of daily expression. At the halfway mark in O. camponoti-floridani infections, when diseased ants show a loss of 24h rhythms in daily foraging, several fungal clock genes, including Frequency, showed differential expression. Network analyses revealed a single gene cluster, containing White Collar 1 and 2, that showed overrepresentation for genes oscillating every 24h in liquid culture as well as genes differentially expressed while growing inside the ant head. ConclusionThis study identifies several sets of putatively clock-controlled genes and biological processes in O. camponoti-floridani that likely plays a role in modifying the behavior of its ant host. Differential expression of O. camponoti-floridani clock genes or 24h-rhythmic genes during infection is suggestive of either a loss of daily rhythm or a change in the amplitude of rhythmic gene expression. Both possibilities would suggest that a disease-associated change occurs to the functioning of the O. camponoti-floridani clock, and its output, while the fungi grows inside the ant head.

molecular biology↗

bioRxiv2022

Natural history and ecological effects on the establishment and fate of Florida carpenter ant cadavers infected by the parasitic manipulator Ophiocordyceps camponoti-floridani.

O_LIOphiocordyceps fungi manipulate the behavior of their ant hosts to produce a summit disease phenotype, thereby establishing infected ant cadavers onto vegetation at elevated positions suitable for fungal growth and transmission. Multiple environmental and ecological factors have been proposed to shape the timing, positioning, and outcome of these manipulations. C_LIO_LIWe conducted a long-term field study of Ophiocordyceps camponoti-floridani infections of Camponotus floridanus ants - the Florida zombie ants. We propose and refine hypotheses on the factors that shape infection outcomes by tracking the occurrence of and fungal growth from hundreds of ant cadavers. We modeled and report these data in relation to weather, light, vegetation, and attack by hyperparasites. C_LIO_LIWe investigated environmental factors that could affect the occurrence and location of newly manipulated ant cadavers. New cadaver occurrence was preferentially biased toward epiphytic Tillandsia bromeliads, canopy openness, and summer weather conditions (an interactive effect of temperature, humidity, and precipitation). Furthermore, we suggest that incident light at the individual cadaver level reflects microhabitat choice by manipulated ants or selective pressure on cadaver maintenance for conditions that improve fungal survival. C_LIO_LIWe also asked which environmental conditions affect fungal fitness. Continued fungal development of reproductive structures and putative transmission increased with moist weather conditions (interaction of humidity and precipitation) and canopy openness, while being reduced by hyperparasitic mycoparasite infections. Moreover, under the most open canopy conditions, we found an atypical Ophiocordyceps growth morphology that could represent a plastic response to conditions influenced by high light levels. C_LIO_LITaken together, we explore general trends and the effects of various ecological conditions on host and parasite disease outcomes in the Florida zombie ant system. These insights from the field can be used to inform experimental laboratory setups that directly test the effects of biotic and abiotic factors on fungus-ant interactions or aim to uncover underlying molecular mechanisms. C_LI

ecology↗

bioRxiv2022

Using machine learning to predict protein-protein interactions between a zombie ant fungus and its carpenter ant host

Parasitic fungi produce proteins that modulate virulence, alter host physiology, and trigger host responses. These proteins, classified as a type of "effector," often act via protein-protein interactions (PPIs). The fungal parasite Ophiocordyceps camponoti-floridani (zombie ant fungus) manipulates Camponotus floridanus (carpenter ant) behavior to promote transmission. The most striking aspect of this behavioral change is a summit disease phenotype where infected hosts ascend and attach to an elevated position. Plausibly, interspecific PPIs drive aspects of Ophiocordyceps infection and host manipulation. Machine learning PPI predictions offer high-throughput methods to produce mechanistic hypotheses on how this behavioral manipulation occurs. Using D-SCRIPT to predict host-parasite PPIs, we found ca. 6,000 interactions involving 2,083 host proteins and 129 parasite proteins, which are encoded by genes upregulated during manipulated behavior. We identified multiple overrepresentations of functional annotations among these proteins. The strongest signals in the host highlighted neuromodulatory G-protein coupled receptors and oxidation-reduction processes. We also detected Camponotus structural and gene-regulatory proteins. In the parasite, we found enrichment of Ophiocordyceps proteases and frequent involvement of novel small secreted proteins with unknown functions. From these results, we provide new hypotheses on potential parasite effectors and host targets underlying zombie ant behavioral manipulation.

molecular biology↗

bioRxiv2020

Genetic underpinnings of host manipulation by Ophiocordyceps as revealed by comparative transcriptomics

AO_SCPLOWBSTRACTC_SCPLOWThe ant-infecting Ophiocordyceps fungi are globally distributed, host manipulating, specialist parasites that drive aberrant behaviors in infected ants, at a lethal cost to the host. An apparent increase in activity and wandering behaviors precedes a final summiting and biting behavior on to vegetation, positioning the manipulated ant in a site beneficial for fungal growth and transmission. Notably, across Ophiocordyceps species and other known host manipulators, the molecular mechanisms underlying behavioral changes remain largely unclear. We explored possible genetic underpinnings of host manipulation by: (i) producing a hybrid assembly of the Ophiocordyceps camponoti-floridani genome, (ii) conducting laboratory infections coupled with RNAseq of both O. camponoti-floridani and its host, Campontous floridanus, and (iii) using these data for a comparative analysis to similar work performed in Ophiocordyceps kimflemingiae and Camponotus castaneus. We propose differentially expressed genes tied to ant neurobiology, odor response, circadian rhythms, and foraging behavior may be the result of putative fungal effectors such as enterotoxins, aflatrem, and mechanisms disrupting nutrition-sensing or caste-identity pathways.

genomics↗