scholarly journals A eDNA-qPCR assay to non-invasively detect the presence of the parasiteSchistocephalus solidusinside its threespine stickleback host

2017 ◽  
Author(s):  
Chloé Suzanne Berger ◽  
Nadia Aubin-Horth

ABSTRACTDetecting the presence of a parasite within its host is crucial to the study of host-parasite interactions. TheSchistocephalus 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-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 theirS. solidusinfection 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.

Parasitology ◽  
2009 ◽  
Vol 137 (3) ◽  
pp. 411-424 ◽  
Author(s):  
I. BARBER ◽  
J. P. SCHARSACK

SUMMARYPlerocercoids of the pseudophyllidean cestodeSchistocephalus solidusinfect the three-spined sticklebackGasterosteus aculeatus, with important consequences for the biology of host fish. Techniques for culturing the parasitein vitroand generating infective stages that can be used to infect sticklebacks experimentally have been developed, and the system is increasingly used as a laboratory model for investigating aspects of host-parasite interactions. Recent experimental laboratory studies have focused on the immune responses of hosts to infection, the consequences of infection for the growth and reproductive development of host fish and the effects of infection on host behaviour. Here we introduce the host and the parasite, review the major findings of these recent experimental infection studies and identify further aspects of host parasite interactions that might be investigated using the system.


Parasitology ◽  
2019 ◽  
Vol 146 (07) ◽  
pp. 883-896
Author(s):  
Hannah M. Strobel ◽  
Sara J. Hays ◽  
Kristine N. Moody ◽  
Michael J. Blum ◽  
David C. Heins

AbstractRemarkably few attempts have been made to estimate contemporary effective population size (Ne) for parasitic species, despite the valuable perspectives it can offer on the tempo and pace of parasite evolution as well as coevolutionary dynamics of host–parasite interactions. In this study, we utilized multi-locus microsatellite data to derive single-sample and temporal estimates of contemporaryNefor a cestode parasite (Schistocephalus solidus) as well as three-spined stickleback hosts (Gasterosteus aculeatus) in lakes across Alaska. Consistent with prior studies, both approaches recovered small and highly variable estimates of parasite and hostNe. We also found that estimates of hostNeand parasiteNewere sensitive to assumptions about population genetic structure and connectivity. And, while prior work on the stickleback–cestode system indicates that physiographic factors external to stickleback hosts largely govern genetic variation inS. solidus, our findings indicate that stickleback host attributes and factors internal to the host – namely body length, genetic diversity and infection – shape contemporaryNeof cestode parasites.


1999 ◽  
Vol 77 (12) ◽  
pp. 1967-1974 ◽  
Author(s):  
David C Heins ◽  
Scarlet S Singer ◽  
John A Baker

We investigated the relationship between reproduction in the threespine stickleback (Gasterosteus aculeatus) and parasitism by plerocercoids of the cestode Schistocephalus solidus in Walby Lake, Alaska, by quantifying stickleback reproduction and parasite infection using 1655 fish from four samples collected in 1990-1996. Stickleback in Walby Lake largely spawned during May and June as 2-year-olds in the second spring-summer after hatching, as was the case with other stickleback populations we studied in south-central Alaska. Contrary to an earlier hypothesis that S. solidus has been selected to delay its deleterious effects on threespine stickleback, i.e., limit its infection levels, until after the stickleback have reproduced, substantial levels of parasitic infection co-occurred with the stickleback reproductive period. Chi-squared analyses of individual samples suggested that in May, infected females were as capable of producing clutches of eggs as uninfected females but in June, S. solidus inhibited clutch production. An overall analysis, however, failed to support the hypothesis that the effect of S. solidus on clutch production differed between early and late periods of the spawning season. We concluded that S. solidus inhibits the ability of female stickleback in Walby Lake to produce a clutch, and that there was no differential effect on clutch production with season. Nonetheless, 77% of all infected females produced clutches. These results contrast with those of one study in which it was found only 9% of infected females became gravid (ripe) and another report that 23% of infected females were able to mature. We offer hypotheses for the co-occurrence of stickleback reproduction and substantial parasitism at the population level and for the ability of a large proportion of infected females to produce clutches. Our results suggest that the host-parasite relationship is more complex than was previously realized.


1983 ◽  
Vol 61 (4) ◽  
pp. 901-908 ◽  
Author(s):  
J. D. McPhail ◽  
S. D. Peacock

Monthly samples of threespine stickleback (Gasterosteus aculeatus) were collected from May through September 1975 from Fuller Lake, Vancouver Island. A total of 2175 adult sticklebacks were collected from 10 trap sites located at depths ranging from 0.25 to 5 m. These samples were assayed for length, weight, sex, state of maturity, and egg number (when applicable). In addition, we recorded the number and weight of the plerocercoids of a cestode tapeworm (Schistocephalus solidus) often found in the abdominal cavities of sticklebacks. The purpose of the study was to document the effects of Schistocephalus on reproduction in Gasterosteus. Stickleback spawning reached a peak in June and declined sharply through July and August. Over the entire breeding season, less than 5% of the gravid females were infected with Schistocephalus, whereas over 40% of the sexually mature but nongravid females were infected. There was no difference between breeding and nonbreeding males in the prevalence of Schistocephalus. In both sexes, the prevalence and severity of Schistocephalus infection were low in May, June, and July but increased sharply through August and September. Since the majority of Fuller Lake sticklebacks live for 1 year, the major adverse effects of Schistocephalus were confined to postreproductive adults. We hypothesize that Schistocephalus plerocercoids have been selected to delay adverse effects on their host until after the host has reproduced.


2016 ◽  
Author(s):  
François Olivier Hébert ◽  
Stephan Grambauer ◽  
Iain Barber ◽  
Christian R Landry ◽  
Nadia Aubin-Horth

ABSTRACTParasites 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 parasite’s 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.


2018 ◽  
Author(s):  
Megan Hahn ◽  
Nolwenn Dheilly

AbstractDespite the growing recognition of the role of bacteria in animal biology, the microbiome of parasites remains largely unexplored. In particular, the presence of bacteria in tapeworms has never been investigated and parasites that exit the intestine would be considered sterile. We characterized for the first time the microbiome of a tapeworm.Schistocephalus solidusplerocercoids, collected from the body cavity of its stickleback host, were found to harbor a complex microbiome. The most abundant and the most prevalent bacteria wasPolynucleobacter sp.. In addition,S. solidusinfection was associated significant changes in the stickleback host gut microbiome with an increase in microbial load and changes in diversity and composition. Finally, the same bacteria were often found inS. solidusand the stomach and intestine of the corresponding hosts, a result that highlights the importance of characterizing the microbiome of host tissues and parasites from the same individuals to assess the potential for horizontal transmission of microbes. This study clearly emphasizes the need for further characterization of the microbiome of a broad range of parasites and for studies to determine the ecological, evolutionary and functional role that microbes play in host-parasite interactions.


Parasitology ◽  
2014 ◽  
Vol 142 (5) ◽  
pp. 719-727 ◽  
Author(s):  
ALEXANDRE BUDRIA ◽  
ULRIKA CANDOLIN

SUMMARYAnthropogenic activities are having profound impacts on species interactions, with further consequences for populations and communities. We investigated the influence that anthropogenic eutrophication has on the prevalence of the parasitic tapeworm Schistocephalus solidus in threespine stickleback Gasterosteus aculeatus populations. We caught stickleback from four areas along the coast of Finland, and within each area from one undisturbed and one eutrophied habitat. We found the prevalence of the parasite to be lower in the eutrophied habitats at the start of the breeding season, probably because of fewer piscivorous birds that transmit the parasite. However, while the prevalence of the parasite declined across the season in the undisturbed habitat, it did less so in eutrophied habitats. We discuss different processes that could be behind the differences, such as lower predation rate on infected fish, higher food availability and less dispersal in eutrophied habitats. We found no effect of eutrophication on the proportion of infected stickleback that entered reproductive condition. Together with earlier findings, this suggests that eutrophication increases the proportion of infected stickleback that reproduce. This could promote the evolution of less parasite resistant populations, with potential consequences for the viability of the interacting parties of the host–parasite system.


Sign in / Sign up

Export Citation Format

Share Document