Prior exposure of a fungal parasite to cyanobacterial extracts does not impair infection of its Daphnia host

Manzi, Florent; Agha, Ramsy; Mühlenhaupt, Max; Wolinska, Justyna

doi:10.1007/s10750-022-04889-7

Cited by 4 publications

(3 citation statements)

References 96 publications

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“…Future work exploring whether Metschnikowia genotypes vary in their sensitivity to phycotoxins and/or time spent in the water column would be valuable, as would studies assessing whether the patterns we found in this study are consistent when other host genotypes (and species) are exposed. Interestingly, a new study that incubated Metschnikowia spores with cyanobacterial extracts or a control solution, then exposed them to two genotypes of Daphnia galeata × longispina (Manzi et al, 2022) suggests that these results might hold broadly. Consistent with our study, they did not find reduced infectivity of spores that had been incubated with the cyanobacterial extract; in fact, for one of the two host genotypes, infectivity of spores that had been incubated with the cyanobacterial extract was actually higher.…”

Section: Discussionmentioning

confidence: 99%

Infectivity of the parasite Metschnikowia bicuspidata is decreased by time spent as a transmission spore, but exposure to phycotoxins in the water column has no effect

et al. 2023

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Transmission from one host to another is a crucial component of parasite fitness. For some aquatic parasites, transmission occurs via a free‐living stage that spends time in the water, awaiting an encounter with a new host. These parasite transmission stages can be impacted by biotic and abiotic factors that influence the parasite's ability to successfully infect or grow in a new host. Here we tested whether time spent in the water column and/or exposure to common cyanobacterial toxins impacted parasite transmission stages. More specifically, we tested whether the infectivity, within host growth, and virulence of the fungal parasite Metschnikowia bicuspidata changed as a result of time spent in the water or from exposure to cyanotoxins in the water column. We exposed parasite transmission spores to different levels of one of two ecologically important cyanotoxins, microcystin‐LR and anatoxin‐a, and factorially manipulated the amount of time spores were incubated in water. We removed the toxins and used those same spores to infect one genotype of the common lake zooplankton Daphnia dentifera. We found that cyanotoxins did not impact parasite fitness (infection prevalence and spore yield per infected host) or virulence (host lifetime reproduction and survivorship) at the tested concentrations (10 and 30 μg/L). However, we found that spending longer as a transmission spore decreased a spore's chances for successful infection: spores that were only incubated for 24 hr infected approximately 75% of exposed hosts, whereas spores incubated for 10 days infected less than 50% of exposed hosts. We also found a negative relationship between the final spore yield from infected hosts and the proportion of hosts that became infected. In treatments where spores spent longer in the water column prior to encountering a host, infection prevalence was lower (indicating lower per spore infectivity), but each infected host yielded more spores at the end of infection. We hypothesise that this pattern may result from intraspecific parasite competition within the host. Overall, these results suggest that transmission spores of this parasite are not strongly influenced by cyanotoxins in the water column, but that other aspects of spending time in the water strongly influence parasite fitness.

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Section: Discussionmentioning

confidence: 99%

Infectivity of the parasite Metschnikowia bicuspidata is decreased by time spent as a transmission spore, but exposure to phycotoxins in the water column has no effect

et al. 2023

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“…However, in a more recent study that used a different strain of Microcystis that produces microcystin-LR and that compared it with a mutant that did not, microcystin-LR did not protect against infection (Sánchez et al 2024). Moreover, two recent studies found that microcystin-LR does not reduce the infectivity of free-living stages of the fungus (Manzi et al 2022, Sánchez et al 2023. While the effect of microcystin-LR on infections is not yet resolved, the overall evidence to date also suggests that the primary effect of Microcystis on infections is most likely due to its production of protease inhibitors rather than the effect of microcystin-LR (Sánchez et al 2024).…”

Section: Scenedesmusmentioning

confidence: 99%

Resource Quality Differentially Impacts Daphnia Interactions with Two Parasites

Fearon,

Sanchez,

Sun

et al. 2024

Preprint

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Resource quality can have conflicting effects on host-parasite interactions; for example, higher resource quality might increase host investment in immune function, or conversely, might permit greater parasite reproduction. Thus, anticipating the impact of changing resource quality on host-parasite interactions is challenging, especially because we often lack a mechanistic understanding of how resource quality influences host physiology and fitness to alter infection outcomes. We investigated whether there are generalizations in how resource quality affects multiple host clones' interactions with different parasites. We used the Daphnia freshwater zooplankton model system to experimentally investigate how a resource quality gradient from high-quality green algae to poor-quality cyanobacteria diets influences host fitness, physiology, and infection by two parasites: a bacterium, Pasteuria ramosa, and a fungus, Metschnikowia bicuspidata. We ran a separate experiment for each parasite using a factorial design with four diets, two Daphnia dentifera host clones, and parasite-inoculated and uninoculated treatments (16 treatments per experiment). Diet strongly influenced infection by the fungus but not the bacterium. These relationships between diet and infection cannot be explained by changes in feeding rate (and, therefore, parasite exposure). Instead, the impact of diet on fungal infection was associated with impacts of diet on the earliest stage of infection: hosts that fed on poor quality diets had very few attacking spores in their guts. Diet did not significantly influence host immune responses. Diet influenced spore production differently for the two parasites, with reduced resource quality limiting the number of fungal spores and the size (but not number) of bacterial spores. Diet, host clone, and infection all affected host fitness. Interestingly, diet influenced the impact of the bacterium, a parasitic castrator that induces gigantism; for one clone, infected hosts fed high quality diets still produced a substantial number of offspring, whereas resource limitation hindered gigantism. Finally, there were often costs of resisting infection, though these generally were not affected by diet. Overall, we show that resource quality differentially impacts the exposure, infection, and proliferation processes for different parasites and host clones, which highlights the need to use multi-genotype and multi-parasite studies to better understand these complex interactions.

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“…A single genotype of the hybrid D. galeata × longispina was used (genotype AMME_51), originating from the same lake and location as the parasite and previously used for experimental infection assays with Metschnikowia (Manzi et al, 2020(Manzi et al, , 2022. Clonal cultures were kept in synthetic SSS-medium (Saebelfeld et al, 2017) at 19°C under a 12:12 hr light-dark photoperiod.…”

Section: Hostmentioning

confidence: 99%