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Jorn P Scharsack - One of the best experts on this subject based on the ideXlab platform.
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early stages of infection of three spined stickleback gasterosteus aculeatus with the cestode Schistocephalus Solidus
Journal of Fish Diseases, 2018Co-Authors: Anika Marie Wohlleben, Joachim Kurtz, Frederik Franke, Madeleine Hamley, Jorn P ScharsackAbstract:Parasitic helminths have evolved strategies to evade their host's immune systems. Particularly, the early time of interactions between helminths and their hosts might be decisive for their infection success. We used the cestode Schistocephalus Solidus, and its highly specific second intermediate host, the three-spined stickleback (Gasterosteus aculeatus) to investigate parasite infection and host cellular immune responses starting 1 day postexposure (dpe). We recovered live parasites from stickleback body cavities already 24 hr after exposure. Infection rates increased up to 50% and did not change from 4 dpe onwards. Thus, not all parasites had reached the body cavity at the early time points and clearance of the parasite at later time points did not occur. Stickleback head kidney leucocytes (HKLs) did not show distinct signs of activation and lymphocyte proliferation, granulocyte-to-lymphocyte ratios and respiratory burst activity of infected sticklebacks did not deviate from controls significantly. The immune system was activated only late, as indicated by an increase in the total count of HKL relative to stickleback weight (HKL per mg fish), which was significantly elevated in infected fish 32 dpe. S. Solidus seems to evade leucocyte activity early during infection facilitating its establishment in the hosts' body cavity.
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specific manipulation or systemic impairment behavioural changes of three spined sticklebacks gasterosteus aculeatus infected with the tapeworm Schistocephalus Solidus
Behavioral Ecology and Sociobiology, 2017Co-Authors: Manuel Talarico, Joachim Kurtz, Franziska Seifert, Josef Lange, Norbert Sachser, Jorn P ScharsackAbstract:Manipulation of host behaviour by parasites to enhance transmission to the next host is a fascinating yet controversial phenomenon. This is because it is often hard to discriminate specific manipulation from unspecific side effects of the infection, i.e. a systemic impairment that could be due to a weakened general body condition. When infected with the tapeworm Schistocephalus Solidus, stickleback fish swim closer to the water surface and exhibit reduced predation avoidance behaviour, which facilitates transmission of the tapeworm to the final host, most often a fish-eating bird. We here tested whether the behavioural changes of infected sticklebacks are specific to contexts where they would indeed enhance transmission, or rather more general. Therefore, we compared the behaviour of sticklebacks that were experimentally infected with S. Solidus or left uninfected, in settings where the behaviour would influence parasite transmission to a high degree (response to a bird predator stimulus) or to a lesser extent (exploration of a new environment, activity while foraging). As expected, infected sticklebacks returned much faster to foraging after the bird predator stimulus and spent more time close to the water surface, compared to non-infected sticklebacks. By contrast, exploration of a new environment and activity while foraging did not differ between infected and non-infected sticklebacks. This suggests that alteration of the sticklebacks’ behaviour when infected with S. Solidus is indeed due to specific manipulation of the predator avoidance behaviour and not a general, systemic impairment of infected sticklebacks. Manipulation of host behaviour by parasites is a fascinating but controversial phenomenon, since it is often difficult to disentangle if they are specifically induced or just a side effect of the infection. Stickleback fish, when infected with a tapeworm, change their behaviour dramatically; they swim closer to the water surface and reduce their escape behaviour, which exposes them to predation by birds, the final hosts of the parasite. We observed that sticklebacks infected with the tapeworm perform equally well as non-infected conspecifics in contexts with low relevance for parasite transmission, such as exploration of a new environment and foraging activity. However, the same infected sticklebacks exhibited the expected reduced escape behaviour when tested with a simulated bird attack. Our study suggests that the parasite specifically induces the sticklebacks’ behavioural changes and does not simply cause a systemic impairment.
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comparative transcriptomics of stickleback immune gene responses upon infection by two helminth parasites diplostomum pseudospathaceum and Schistocephalus Solidus
Zoology, 2016Co-Authors: David Haase, Martin Kalbe, Jorn P Scharsack, Jennifer K. Rieger, Anika Witten, Monika Stoll, Erich Bornbergbauer, Alexander Schmidtdrewello, Thorsten B H ReuschAbstract:Immune systems of vertebrates are much more diverse than previously thought, in particular at the base of the vertebrate clade. RNA-seq was used to describe in detail the transcriptomic response of stickleback hosts to infection by two helminth parasites, the trematode Diplostomum pseudospathaceum (2 genotypes plus a genotype mix) and the cestode Schistocephalus Solidus. Based on a global transcription profiling, we present immune genes that are active during chronic or multiple repeated infection. We found that the transcription profiles of D. pseudospathaceum genotypes were as divergent as those of the two parasite species. When comparing the host immune response, only 5 immune genes were consistently upregulated upon infection by both species. These genes indicated a role for enhanced toll like receptor (TLR) activity (CTSK, CYP27B1) and an associated positive regulation of macrophages (CYP27B1, THBS1) for general helminth defense. We interpret the largely differentiated gene expression response among parasite species as general redundancy of the vertebrate immune system, which was also visible in genotype-specific responses among the different D. pseudospathaceum infections. The present study provides the first evidence that IL4-mediated activation of T-helper lymphocyte cells is also important in anti-helminthic immune responses of teleost fish.
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reciprocal cross infection of sticklebacks with the diphyllobothriidean cestode Schistocephalus Solidus reveals consistent population differences in parasite growth and host resistance
Parasites & Vectors, 2016Co-Authors: Martin Kalbe, Christophe Eizaguirre, Jorn P Scharsack, Per Johan JakobsenAbstract:In host-parasite evolutionary arms races, parasites are generally expected to adapt more rapidly, due to their large population sizes and short generation times. There exist systems, though, where parasites cannot outpace their hosts because of similar generation times in both antagonists. In those cases concomitant adaptation is expected. We tested this hypothesis in the three-spined stickleback-Schistocephalus Solidus tapeworm system, where generation times are comparable in both organisms. We chose two populations of sticklebacks which differ prominently in the prevalence of S. Solidus and consequently in its level of selective pressure. We performed a full factorial common garden experiment. Particularly, Norwegian (NO) and German (DE) sticklebacks, as well as hybrids between both stickleback populations and in both parental combinations, were exposed each to a single S. Solidus originating from the same two host populations. We found the infection phenotype to depend on the host population, the parasite population, but not their interaction. NO-parasites showed higher infectivity than DE-parasites, with NO-sticklebacks also being more resistant to DE-parasites than to the sympatric NO-parasite. Reciprocally, DE-hosts were more susceptible to the allopatric NO-parasite while DE-parasites grew less than NO-parasites in all stickleback groups. Despite this asymmetry, the ratio of worm to host weight, an indicator of parasite virulence, was identical in both sympatric combinations, suggesting an optimal virulence as a common outcome of parallel coevolved systems. In hybrid sticklebacks, intermediate infection rates and growth of S. Solidus from either origin suggests a simple genetic basis of resistance. However, comparison of infection phenotypes in NO-maternal and DE-maternal hybrid sticklebacks indicates local adaptation to the sympatric counterpart in both the host and the parasite. Host-parasite systems with similar generation time show evidence for concomitant reciprocal adaptation resulting in parasite optimal virulence and host parasite specific resistance.
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In vitro effects of prostaglandin E2 on leucocytes from sticklebacks (Gasterosteus aculeatus) infected and not infected with the cestode Schistocephalus Solidus.
Fish & shellfish immunology, 2014Co-Authors: Ivan Kutyrev, Joachim Kurtz, Frederik Franke, Janine Büscher, Jorn P ScharsackAbstract:Many helminth parasites have evolved strategies to evade the immune response of their hosts, which includes immunomodulation. Prostaglandin E2 (PGE2) is one of the best-described immunomodulators in mammalian helminth parasite infections. We hypothesized that also in teleost fish anti-helminthic immune responses are regulated via PGE2. We used a model system consisting of the tapeworm Schistocephalus Solidus and its host, the three-spined stickleback (Gasterosteus aculeatus), to investigate in vitro effects of PGE2 on head kidney leucocytes (HKL) derived from sticklebacks that were experimentally infected with S. Solidus. PGE2 was tested alone or in combination with either S. Solidus antigens or bacterial lipopolysaccharides (LPS). After in vitro culture, cell viability and changes in leucocyte subpopulations (granulocytes to lymphocytes ratios) were monitored by flow cytometry and HKL were tested for their capacity to produce reactive oxygen species (ROS) with a chemiluminescence assay. In short term (2 h) HKL cultures PGE2 did not change the total numbers of live HKL, but the production of ROS decreased significantly with high (0.1 μmol L(-1)) PGE2 concentrations. In long-term (96 h) cultures high PGE2 concentrations induced a sharp decrease of leucocytes viability, while low (0.1 pmol L(-1)) and intermediate (0.1 nmol L(-1)) concentrations of PGE2 caused elevated leucocyte viability compared to controls. This coincided with reduced ROS production in cultures with high PGE2 and elevated ROS production in cultures with low PGE2. Granulocyte to lymphocyte ratios increased with high PGE2 concentrations alone and in combination with S. Solidus antigens and LPS, most prominently with HKL from S. Solidus infected sticklebacks. The present study supports the hypothesis that PGE2 might be an immunomodulator in tapeworm-fish parasite-host interactions.
David C. Heins - One of the best experts on this subject based on the ideXlab platform.
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are solo infections of the diphyllobothriidean cestode Schistocephalus Solidus more virulent than multiple infections
Parasitology, 2019Co-Authors: David C. Heins, Kristine N Moody, Sophia MillerAbstract:We performed a long-term natural experiment investigating the impact of the diphyllobotriidean cestode Schistocephalus Solidus on the body condition and clutch size (CS) of threespine stickleback Gasterosteus aculeatus, its second intermediate host, and the growth of larval parasites in host fish. We tested the hypothesis that single S. Solidus infections were more virulent than multiple infections. We also asked whether the metrics of mean and total parasite mass (proxies for individual and total volume, respectively) were consistent with predictions of the resource constraints or the life history strategy (LHS) hypothesis for the growth of, hence exploitation by, larval helminths in intermediate hosts. The samples were drawn from Walby Lake, Alaska in eight of 11 years. Host body condition and CS (egg number per spawning bout) decreased significantly with intensity after adjustments for host size and parasite index. Thus, infections have an increasingly negative impact on measures of host fitness with greater intensity, in contrast to the hypothesis that single infections are more harmful than multiple infections. We also found that mean parasite mass decreased with intensity while total parasite mass increased with intensity as predicted by the LHS hypothesis.
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Timing of Infections in the Threespine Stickleback (Gasterosteus aculeatus) by Schistocephalus Solidus in Alaska.
The Journal of parasitology, 2015Co-Authors: David C. Heins, D. M. Eidam, John A. BakerAbstract:Abstract This study provides direct evidence for the timing of infections by Schistocephalus Solidus in the threespine stickleback (Gasterosteus aculeatus) of south-central Alaska. Young-of-the-year fish in Cheney Lake were infected during their first summer within a few months after hatching in May–June. Infections appear to continue under ice cover on the lake during the subsequent fall and winter. Few, if any, 1-yr-old fish seemed to be infected for the first time, although 1-yr-old hosts with established parasites apparently acquired additional infections.
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Landscape Genetics of Schistocephalus Solidus Parasites in Threespine Stickleback (Gasterosteus aculeatus) from Alaska
PloS one, 2015Co-Authors: C. Grace Sprehn, Michael J. Blum, Thomas P. Quinn, David C. HeinsAbstract:The nature of gene flow in parasites with complex life cycles is poorly understood, particularly when intermediate and definitive hosts have contrasting movement potential. We examined whether the fine-scale population genetic structure of the diphyllobothriidean cestode Schistocephalus Solidus reflects the habits of intermediate threespine stickleback hosts or those of its definitive hosts, semi-aquatic piscivorous birds, to better understand complex host-parasite interactions. Seventeen lakes in the Cook Inlet region of south-central Alaska were sampled, including ten in the Matanuska-Susitna Valley, five on the Kenai Peninsula, and two in the Bristol Bay drainage. We analyzed sequence variation across a 759 bp region of the mitochondrial DNA (mtDNA) cytochrome oxidase I region for 1,026 S. Solidus individuals sampled from 2009-2012. We also analyzed allelic variation at 8 microsatellite loci for 1,243 individuals. Analysis of mtDNA haplotype and microsatellite genotype variation recovered evidence of significant population genetic structure within S. Solidus. Host, location, and year were factors in structuring observed genetic variation. Pairwise measures revealed significant differentiation among lakes, including a pattern of isolation-by-distance. Bayesian analysis identified three distinct genotypic clusters in the study region, little admixture within hosts and lakes, and a shift in genotype frequencies over time. Evidence of fine-scale population structure in S. Solidus indicates that movement of its vagile, definitive avian hosts has less influence on gene flow than expected based solely on movement potential. Observed patterns of genetic variation may reflect genetic drift, behaviors of definitive hosts that constrain dispersal, life history of intermediate hosts, and adaptive specificity of S. Solidus to intermediate host genotype.
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consistency of host responses to parasitic infection in the three spined stickleback fish infected by the diphyllobothriidean cestode Schistocephalus Solidus
Biological Journal of The Linnean Society, 2014Co-Authors: David C. Heins, Kelly Barry, Laura A PetrauskasAbstract:Among populations of the three-spined stickleback fish in Alaska, females appear to show two forms of sterility tolerance to infection by the diphyllobothriidean cestode Schistocephalus Solidus. In contrast to sticklebacks in other regions of the northern hemisphere, female fish are capable of producing clutches of eggs despite supporting large parasite burdens. Nonetheless, nutrient loss to the parasite, coupled with the energetic demands of host reproduction, eventually curtails spawning among infected females. Host females in Walby Lake experience ‘fecundity reduction’ resulting from nutrient theft as a side effect of infection. In Scout Lake, infected females show ‘fecundity compensation’, an adaptive, inducible response allowing them to increase current fecundity to compensate for reduction or loss of future reproduction. This multi-year study of sticklebacks from each lake addresses two empirical questions for a better understanding of the dynamic interplay between host and parasite. First, is there is any annual variation within the two responses to parasitism in each host population; and, if so, is it related to parasite burden? Second, do the two host responses show consistent differences between the populations of sticklebacks despite any yearly variation in them? We found annual, intra-population variation within the response shown by each population of stickleback which appears to have been influenced by the parasite : host mass ratio and possibly by unknown environmental conditions affecting the reproductive physiology of stickleback females. Moreover, the data support the hypothesis that ovum mass is more sensitive to parasitism (parasite burden) than clutch size in females from Walby Lake which exhibit fecundity reduction. Notwithstanding the intra-population variation within each host response, the responses to infection occurred consistently within each respective stickleback population and appear to reflect stable, fundamental characteristics of the populations. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 958–968.
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fecundity compensation and fecundity reduction among populations of the three spined stickleback infected by Schistocephalus Solidus in alaska
Parasitology, 2014Co-Authors: David C. Heins, John A. BakerAbstract:We surveyed nine populations of the three-spined stickleback infected by the diphyllobothriidean cestode Schistocephalus Solidus from south-central Alaska for two apparent forms of tolerance to infection in females capable of producing egg clutches notwithstanding large parasite burdens. Seven populations exhibited fecundity reduction, whereas two populations showed fecundity compensation. Our data suggest that fecundity reduction, a side effect resulting from nutrient theft, occurs in two phases of host response influenced by the parasite : host body mass (BM) ratio. The first is significantly reduced ovum mass without significant reduction in clutch size, and the second one involves significant reductions in both ovum mass and clutch size. Thus, ovum mass of host females who are functionally being starved through nutrient theft seems to be more readily influenced by parasitism and, therefore, decreased before clutch size is reduced. This inference is consistent with expectations based on the biology of and effect of feeding ration on reproduction in stickleback females. Fecundity compensation appears to be uncommon among populations of three-spined stickleback in Alaska and rare among populations throughout the northern hemisphere. Fecundity reduction seems to be common, at least among stickleback populations in Alaska.
Nadia Aubinhorth - One of the best experts on this subject based on the ideXlab platform.
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an edna qpcr assay to detect the presence of the parasite Schistocephalus Solidus inside its threespine stickleback host
The Journal of Experimental Biology, 2018Co-Authors: Chloé Suzanne Berger, Nadia AubinhorthAbstract:Detecting the presence of a parasite within its host is crucial to the study of host-parasite interactions. The Schistocephalus Solidus-threespine stickleback pair has been studied extensively to investigate host phenotypic alterations associated with a parasite with a complex life cycle. This cestode is localized inside the stickleback's abdominal cavity and can be visually detected only once it passes a mass threshold. We present a non-lethal quantitative PCR (qPCR) approach based on detection of environmental DNA from the worm (eDNA), sampled in the fish abdominal cavity. Using this approach on two fish populations (n=151), 98% of fish were correctly assigned to their S. Solidus infection status. There was a significant correlation between eDNA concentration and total parasitic mass. We also assessed ventilation rate as a complementary mean to detect infection. Our eDNA detection method gives a reliable presence/absence response and its future use for quantitative assessment of infection is promising.
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a edna qpcr assay to non invasively detect the presence of the parasite Schistocephalus Solidus inside its threespine stickleback host
bioRxiv, 2018Co-Authors: Chloé Suzanne Berger, Nadia AubinhorthAbstract:Detecting the presence of a parasite within its host is crucial to the study of host-parasite interactions. The Schistocephalus Solidus - threespine stickleback pair has been studied extensively to investigate host phenotypic alterations associated with a parasite with a complex life cycle. This cestode is localized inside the stickleback9s abdominal cavity and can be visually detected only once it passes a mass threshold. We present a non-invasive quantitative PCR approach based on detection of environmental DNA from the worm (eDNA), sampled in the fish abdominal cavity. Using this approach on two fish populations (n=151), 98% of fish were correctly assigned to their S. Solidus infection status. There was a significant correlation between eDNA concentration and total parasitic mass. We also assessed ventilation rates as a complimentary mean to detect infection. Our eDNA detection method gives a reliable presence/absence response and its future use for quantitative assessment is promising.
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a edna qpcr combination assay to non invasively detect the presence of the parasite Schistocephalus Solidus inside its intermediate host the threespine stickleback
bioRxiv, 2017Co-Authors: Chloé Suzanne Berger, Nadia AubinhorthAbstract:To study parasite-host interactions, it is of major importance to detect the presence of the parasite during its development in the host. The Schistocephalus Solidus-threespine stickleback pair has been used extensively to study host phenotypic alterations caused by a parasite with a complex life cycle. This cestode worm is localized inside the abdominal cavity of its intermediate fish host, which limits its detection to the time when it has grown substantially or to multiple infections. Here, we present a non-invasive species-specific quantitative real time PCR approach based on the detection of environmental DNA from the worm (eDNA), sampled directly in the abdominal cavity of the threespine stickleback. Using this approach on two fish populations (n=151), 98% of fish were correctly assigned to their S. Solidus infection status. Among the 35 sticklebacks that harboured single or multiple infections, only 3 were not detected as infected. Furthermore, non-infected sticklebacks were never incorrectly identified as infected. There was a significant correlation between eDNA concentration and the total mass of parasites. We also assessed ventilation rates as a rapid and complimentary mean to detect infection (n=20). Ventilation rates were repeatable over 3 measurements, did not vary significantly between non-infected and infected fish, were not significantly correlated to the parasite index, and thus could not reliably be used to predict infection. Our eDNA approach could be used in this parasite-host system alone or in combination with morphological measurements to detect S. Solidus.
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can the behaviour of threespine stickleback parasitized with Schistocephalus Solidus be replicated by manipulating host physiology
The Journal of Experimental Biology, 2017Co-Authors: Lucie Grecias, François Olivier Hébert, Iain Barber, Chloé Suzanne Berger, Nadia AubinhorthAbstract:Sticklebacks infected by the parasitic flatworm Schistocephalus Solidus show dramatic changes in phenotype, including a loss of species-typical behavioural responses to predators. The timing of host behaviour change coincides with the development of infectivity of the parasite to the final host (a piscivorous bird), making it an ideal model for studying the mechanisms of infection-induced behavioural modification. However, whether the loss of host anti-predator behaviour results from direct manipulation by the parasite, or is a by-product (e.g. host immune response) or side effect of infection (e.g. energetic loss), remains controversial. To understand the physiological mechanisms that generate these behavioural changes, we quantified the behavioural profiles of experimentally infected fish and attempted to replicate these in non-parasitized fish by exposing them to treatments including immunity activation and fasting, or by pharmacologically inhibiting the stress axis. All fish were screened for the following behaviours: activity, water depth preference, sociability, phototaxis, anti-predator response and latency to feed. We were able to change individual behaviours with certain treatments. Our results suggest that the impact of S. Solidus on the stickleback might be of a multifactorial nature. The behaviour changes observed in infected fish might result from the combined effects of modifying the serotonergic axis, lack of energy and activation of the immune system.
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major host transitions are modulated through transcriptome wide reprograming events in Schistocephalus Solidus a threespine stickleback parasite
bioRxiv, 2016Co-Authors: François Olivier Hébert, Stephan Grambauer, Iain Barber, Christian R. Landry, Nadia AubinhorthAbstract:Parasites with complex life cycles have developed numerous phenotypic strategies, closely associated with developmental events, to enable the exploitation of different ecological niches and facilitate transmission between hosts. How these environmental shifts are regulated from a metabolic and physiological standpoint, however, still remain to be fully elucidated. We examined the transcriptomic response of Schistocephalus Solidus , a trophically-transmitted parasite with a complex life cycle, over the course of its development in an intermediate host, the threespine stickleback, and the final avian host. Results from our differential gene expression analysis show major reprogramming events among developmental stages. The final host stage is characterized by a strong activation of reproductive pathways and redox homeostasis. The attainment of infectivity in the fish intermediate host - which precedes sexual maturation in the final host and is associated with host behaviour changes - is marked by transcription of genes involved in neural pathways and sensory perception. Our results suggest that un-annotated and S. Solidus -specific genes could play a determinant role in host-parasite molecular interactions required to complete the parasite9s life cycle. Our results permit future comparative analyses to help disentangle species-specific patterns of infection from conserved mechanisms, ultimately leading to a better understanding of the molecular control and evolution of complex life cycles.
Iain Barber - One of the best experts on this subject based on the ideXlab platform.
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can the behaviour of threespine stickleback parasitized with Schistocephalus Solidus be replicated by manipulating host physiology
The Journal of Experimental Biology, 2017Co-Authors: Lucie Grecias, François Olivier Hébert, Iain Barber, Chloé Suzanne Berger, Nadia AubinhorthAbstract:Sticklebacks infected by the parasitic flatworm Schistocephalus Solidus show dramatic changes in phenotype, including a loss of species-typical behavioural responses to predators. The timing of host behaviour change coincides with the development of infectivity of the parasite to the final host (a piscivorous bird), making it an ideal model for studying the mechanisms of infection-induced behavioural modification. However, whether the loss of host anti-predator behaviour results from direct manipulation by the parasite, or is a by-product (e.g. host immune response) or side effect of infection (e.g. energetic loss), remains controversial. To understand the physiological mechanisms that generate these behavioural changes, we quantified the behavioural profiles of experimentally infected fish and attempted to replicate these in non-parasitized fish by exposing them to treatments including immunity activation and fasting, or by pharmacologically inhibiting the stress axis. All fish were screened for the following behaviours: activity, water depth preference, sociability, phototaxis, anti-predator response and latency to feed. We were able to change individual behaviours with certain treatments. Our results suggest that the impact of S. Solidus on the stickleback might be of a multifactorial nature. The behaviour changes observed in infected fish might result from the combined effects of modifying the serotonergic axis, lack of energy and activation of the immune system.
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major host transitions are modulated through transcriptome wide reprograming events in Schistocephalus Solidus a threespine stickleback parasite
bioRxiv, 2016Co-Authors: François Olivier Hébert, Stephan Grambauer, Iain Barber, Christian R. Landry, Nadia AubinhorthAbstract:Parasites with complex life cycles have developed numerous phenotypic strategies, closely associated with developmental events, to enable the exploitation of different ecological niches and facilitate transmission between hosts. How these environmental shifts are regulated from a metabolic and physiological standpoint, however, still remain to be fully elucidated. We examined the transcriptomic response of Schistocephalus Solidus , a trophically-transmitted parasite with a complex life cycle, over the course of its development in an intermediate host, the threespine stickleback, and the final avian host. Results from our differential gene expression analysis show major reprogramming events among developmental stages. The final host stage is characterized by a strong activation of reproductive pathways and redox homeostasis. The attainment of infectivity in the fish intermediate host - which precedes sexual maturation in the final host and is associated with host behaviour changes - is marked by transcription of genes involved in neural pathways and sensory perception. Our results suggest that un-annotated and S. Solidus -specific genes could play a determinant role in host-parasite molecular interactions required to complete the parasite9s life cycle. Our results permit future comparative analyses to help disentangle species-specific patterns of infection from conserved mechanisms, ultimately leading to a better understanding of the molecular control and evolution of complex life cycles.
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transcriptome sequences spanning key developmental states as a resource for the study of the cestode Schistocephalus Solidus a threespine stickleback parasite
GigaScience, 2016Co-Authors: François Olivier Hébert, Stephan Grambauer, Iain Barber, Christian R. Landry, Nadia AubinhorthAbstract:Background Schistocephalus Solidus is a well-established model organism for studying the complex life cycle of cestodes and the mechanisms underlying host-parasite interactions. However, very few large-scale genetic resources for this species are available. We have sequenced and de novo-assembled the transcriptome of S. Solidus using tissues from whole worms at three key developmental states - non-infective plerocercoid, infective plerocercoid and adult plerocercoid - to provide a resource for studying the evolution of complex life cycles and, more specifically, how parasites modulate their interactions with their hosts during development.
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Transcriptome sequences spanning key developmental states as a resource for the study of the cestode Schistocephalus Solidus, a threespine stickleback parasite
2016Co-Authors: François Olivier Hébert, Stephan Grambauer, Iain Barber, Christian R. Landry, Nadia Aubin-horthAbstract:BACKGROUND: Schistocephalus Solidus is a well-established model organism for studying the complex life cycle of cestodes and the mechanisms underlying host-parasite interactions. However, very few large-scale genetic resources for this species are available. We have sequenced and de novo-assembled the transcriptome of S. Solidus using tissues from whole worms at three key developmental states - non-infective plerocercoid, infective plerocercoid and adult plerocercoid - to provide a resource for studying the evolution of complex life cycles and, more specifically, how parasites modulate their interactions with their hosts during development. FINDINGS: The de novo transcriptome assembly reconstructed the coding sequence of 10,285 high-confidence unigenes from which 24,765 non-redundant transcripts were derived. 7,920 (77 %) of these unigenes were annotated with a protein name and 7,323 (71 %) were assigned at least one Gene Ontology term. Our raw transcriptome assembly (unfiltered transcripts) covers 92 % of the predicted transcriptome derived from the S. Solidus draft genome assembly currently available on WormBase. It also provides new ecological information and orthology relationships to further annotate the current WormBase transcriptome and genome. CONCLUSION: This large-scale transcriptomic dataset provides a foundation for studies on how parasitic species with complex life cycles modulate their response to changes in biotic and abiotic conditions experienced inside their various hosts, which is a fundamental objective of parasitology. Furthermore, this resource will help in the validation of the S Solidus gene features that have been predicted based on genomic sequence
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The Effect of Salinity on Egg Development and Viability of Schistocephalus Solidus (Cestoda: Diphyllobothriidea)
The Journal of parasitology, 2015Co-Authors: Natalie E. Simmonds, Iain BarberAbstract:Schistocephalus Solidus plerocercoids commonly infect three-spined stickleback Gasterosteus aculeatus populations in brackish and freshwaters, but infections are typically absent from marine populations. Here we provide an experimental test of the salinity tolerance of S. Solidus eggs, to determine the role of salinity in limiting the distribution of infection in coastal zones. We find that S. Solidus eggs, derived from the in vitro culture of 3 different plerocercoids, developed normally in salinities of up to 12.5‰, but above this egg viability dropped rapidly, and no egg hatching was observed at salinities above 20‰. Our results are consistent with the distribution of infections in natural stickleback populations and add resolution to previous descriptive observations on salinity tolerance in S. Solidus. They also demonstrate that S. Solidus presents a novel disease challenge to marine populations of three-spined sticklebacks entering brackish and freshwater environments.
Manfred Milinski - One of the best experts on this subject based on the ideXlab platform.
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in vitro transition of Schistocephalus Solidus cestoda from coracidium to procercoid and from procercoid to plerocercoid
Experimental Parasitology, 2012Co-Authors: Per Johan Jakobsen, Katrin Hammerschmidt, Martin Kalbe, Jorn P Scharsack, Peter Deines, Manfred MilinskiAbstract:With the present study, a culture system for successive life-cycle stages of the tapeworm Schistocephalus Solidus was developed and this report documents for the first time, cultivation of the procercoid stage of S. Solidus from eggs. Additionally we have transformed procercoids dissected from experimentally infected copepods and cultured procercoids into the early plerocercoid stage in vitro. Observations in the culture suggest that the coracidia can interact with their external environment and need no host specific stimuli, except for the components in the culture medium, for activation and hatching from the embryophore. Increasing the culture medium pH from 7.3 to 8.0 improved escape rates and frequencies of hook contractions, suggesting that the oncosphere may recognize and respond to environmental conditions along the host intestine. Procercoids in the culture did not stop growing indicating that conditions within the copepod may be important to limit growth and to induce transformation to plerocercoids. When procercoids are dissected from copepods and transferred to the culture, the outer tegument layers and cercomer starts to loosen. Comparison of the lectin staining of the loosened outer tegument layers and cercomer in procercoids dissected from copepods confirms that transitions of both, the oncosphere to procercoid and procercoid to plerocercoids, has taken place in the in vitro cultures.
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host parasite interactions in a cestode with a complex life cycle Schistocephalus Solidus
2006Co-Authors: Katrin Hammerschmidt, Manfred Milinski, M SpindlerAbstract:Many parasites have complex life cycles, i.e. they have to pass through several host species to reach maturity. Hence complex life cycles often consist of invertebrate and vertebrate hosts, the parasite likely varies in the machinery required for infection, exploitation and transmission of each host. Does the ability to optimally exploit one host inevitably lead to a reduced ability for the parasite to exploit another host in its life cycle? To answer this question, I analysed parasite life history traits like transmission, infection, and establishment in the model system of the tapeworm Schistocephalus Solidus in relation to its two intermediate hosts, a cyclopoid copepod, and the three-spined stickleback. In this thesis, I particularly focus on interactions with the hosts' immune systems and on constraints, which are potentially shaping the evolution of virulence in parasites with complex life cycles.
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hosts and parasites many ways of interactions an approach with two model organisms the three spined stickleback gasterosteus aculeatus and its cestode parasite Schistocephalus Solidus
2006Co-Authors: Ilonka Jager, Manfred Milinski, Heinz BrendelbergerAbstract:Parasites are considered to be one of the major driving forces in the evolution of organisms. The outcome of an infection might, however, not only be determined by host-parasite interactions but also by within-host dynamics. Using the three-spined stickleback (Gasterosteus aculeatus) and the tapeworm Schistocephalus Solidus as model organisms, this thesis addresses various aspects of such interactions. Apart from parasite mate choice as potentially important parasite-parasite interaction, dynamics of multiple infections and various aspects of the host's immune system were investigated.
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Fitness consequences of selfing and outcrossing in the cestode Schistocephalus Solidus
Integrative and comparative biology, 2006Co-Authors: Manfred MilinskiAbstract:Synopsis Mixed-mating, that is reproduction by both self-fertilization and cross-fertilization is common in hermaphroditic parasites. Its maintenance poses, however, a problem for evolutionary biology. The tapeworm Schistocephalus Solidus Muller 1776, served as a model to study experimentally the consequences of selfing and outcrossing in its 2 consecutive intermediate hosts, a copepod (Macrocyclops albidus Jurine) and the three-spined stickleback fish (Gasterosteus aculeatus). Size-matched tapeworms were allowed to reproduce either alone or in pairs in an in vitro system that replaced the definitive bird host's gut. Selfed eggs from singletons had a 4 times lower hatching success than outcrossed eggs from pairs. Outcrossed offspring achieved both a higher infection success and a higher weight in the copepod, and a higher number of parasites per host in both intermediate hosts, but only under competition. Outcrossed offspring were generally more successful. If a S. Solidus plerocercoid has a partner in the bird's gut, they should outcross unless they differ in size and thus cannot solve the Hermaphrodite's Dilemma cooperatively. Using microsatellite markers, the proportion of selfed offspring and the total reproductive output of each worm within pairs varying in mean weight and in weight difference was measured. Worms produced more selfed offspring not only with increasing weight difference as expected but also with decreasing total weight of the pair. If small worms were selfed, they have already purged deleterious mutations and would thus be better selfers in a year with low parasite density when worms cannot find partners. To maintain this advantage they should self a higher proportion of their eggs even with a partner. Here I review recent exprimental evidence.
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competitive growth strategies in intermediate hosts experimental tests of a parasite life history model using the cestode Schistocephalus Solidus
Evolutionary Ecology, 2006Co-Authors: Marilyn Michaud, Manfred Milinski, G A Parker, James C ChubbAbstract:In parasites with a complex life cycle, the fitness of an individual depends on its probability of reaching the final host and on its fecundity. Because larval growth in intermediate hosts may affect both transmission and adult size, selection should optimize growth patterns that are conditional on the presence and number of conspecific competitors. A recent model predicts that the total parasite volume per host should increase with intensity if larvae are able to vary growth depending on the number of conspecifics in the host (Life History Strategy hypothesis, i.e. LHS). Further, we would here expect growth rates to increase with intensity. By contrast, under the simplest alternative hypothesis of Resource Constraints (i.e. RC), the total parasite volume should remain constant. We experimentally infected copepods Macrocyclops albidus with the cestode Schistocephalus Solidus to achieve 1, 2 or 3 parasites per host taking care that hosts had similar quality status at each infection level, and compared larval growth trajectories at the three intensity levels. The asymptotic total parasite volume was larger in double and triple infections than in single infections. Furthermore, the asymptotic total parasite volume was significantly larger in triple than in double infections but only in larger copepods that were less constrained by a host-size ceiling effect. These results, together with the fact that growth rates increased with intensity, support the LHS hypothesis: procercoids of a tapeworm may “count” their conspecific competitors in their first intermediate host to harvest its resources strategically until the next step in their complex life cycle.
