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1

Olfaction shapes host-parasite interactions in parasitic nematodes.  

PubMed

Many parasitic nematodes actively seek out hosts in which to complete their lifecycles. Olfaction is thought to play an important role in the host-seeking process, with parasites following a chemical trail toward host-associated odors. However, little is known about the olfactory cues that attract parasitic nematodes to hosts or the behavioral responses these cues elicit. Moreover, what little is known focuses on easily obtainable laboratory hosts rather than on natural or other ecologically relevant hosts. Here we investigate the olfactory responses of six diverse species of entomopathogenic nematodes (EPNs) to seven ecologically relevant potential invertebrate hosts, including one known natural host and other potential hosts collected from the environment. We show that EPNs respond differentially to the odor blends emitted by live potential hosts as well as to individual host-derived odorants. In addition, we show that EPNs use the universal host cue CO(2) as well as host-specific odorants for host location, but the relative importance of CO(2) versus host-specific odorants varies for different parasite-host combinations and for different host-seeking behaviors. We also identified host-derived odorants by gas chromatography-mass spectrometry and found that many of these odorants stimulate host-seeking behaviors in a species-specific manner. Taken together, our results demonstrate that parasitic nematodes have evolved specialized olfactory systems that likely contribute to appropriate host selection. PMID:22851767

Dillman, Adler R; Guillermin, Manon L; Lee, Joon Ha; Kim, Brian; Sternberg, Paul W; Hallem, Elissa A

2012-08-28

2

A host-parasite multilevel interacting process and continuous approximations  

E-print Network

A host-parasite multilevel interacting process and continuous approximations Sylvie Méléard1) and the evolution of cells (or parasites) of two types living in these individuals. The ecological parameters-death-mutation-competition point process, host-parasite stochastic particle system, nonlinear integro-differential equations

Potsdam, Universität

3

The mode of host-parasite interaction shapes coevolutionary dynamics and the fate of host cooperation  

E-print Network

The mode of host-parasite interaction shapes coevolutionary dynamics and the fate of host host- parasite model there are four mechanisms: host birth (bacterial duplication), competition among hosts for finite resources, parasite death (virus degradation) and lysis of a bacterium by a phage

McKane, Alan

4

Diet quality determines interspecific parasite interactions in host populations  

PubMed Central

The widespread occurrence of multiple infections and the often vast range of nutritional resources for their hosts allow that interspecific parasite interactions in natural host populations might be determined by host diet quality. Nevertheless, the role of diet quality with respect to multispecies parasite interactions on host population level is not clear. We here tested the effect of host population diet quality on the parasite community in an experimental study using Daphnia populations. We studied the effect of diet quality on Daphnia population demography and the interactions in multispecies parasite infections of this freshwater crustacean host. The results of our experiment show that the fitness of a low-virulent microsporidian parasite decreased in low, but not in high-host-diet quality conditions. Interestingly, infections with the microsporidium protected Daphnia populations against a more virulent bacterial parasite. The observed interspecific parasite interactions are discussed with respect to the role of diet quality-dependent changes in host fecundity. This study reflects that exploitation competition in multispecies parasite infections is environmentally dependent, more in particular it shows that diet quality affects interspecific parasite competition within a single host and that this can be mediated by host population-level effects. PMID:25247066

Lange, Benjamin; Reuter, Max; Ebert, Dieter; Muylaert, Koenraad; Decaestecker, Ellen

2014-01-01

5

Host-Parasite Interactions in Some Fish Species  

PubMed Central

Host-parasite interactions are complex, compounded by factors that are capable of shifting the balance in either direction. The host's age, behaviour, immunological status, and environmental change can affect the association that is beneficial to the host whereas evasion of the host's immune response favours the parasite. In fish, some infections that induce mortality are age and temperature dependent. Environmental change, especially habitat degradation by anthropogenic pollutants and oceanographic alterations induced by climatic, can influence parasitic-host interaction. The outcome of these associations will hinge on susceptibility and resistance. PMID:22900144

Khan, R. A.

2012-01-01

6

The effect of host heterogeneity and parasite intragenomic interactions on parasite  

E-print Network

The effect of host heterogeneity and parasite intragenomic interactions on parasite population Bank, Sheffield S10 2TN, UK Understanding the processes that shape the genetic structure of parasite populations and the functional consequences of different parasite genotypes is critical for our ability

Paterson, Steve

7

Host-parasite interactions between eastern bluebirds (Sialia sialis) and their blowfly (Protocalliphora sp) parasites  

Microsoft Academic Search

Nestling birds are often parasitized while in the nest, and the parasites can have significant negative effects on the nestlings. I examined the host-parasite interactions between eastern bluebirds (Sialia sialis) and their blowfly (Protocalliphora sp.) parasites over three field seasons in a Pennsylvania bluebird population. I randomly divided broods into control and experimental groups. Control broods had natural levels of

Kristina Michele Hannam

1998-01-01

8

On the evolutionary ecology of host-parasite interactions: addressing the question with regard to bumblebees and their parasites  

Microsoft Academic Search

Over the last decade, there has been a major shift in the study of adaptive patterns and processes towards including the role of host-parasite interactions, informed by concepts from evolutionary ecology. As a consequence, a number of major questions have emerged. For example, how genetics affects host-parasite interactions, whether parasitism selects for offspring diversification, whether parasite virulence is an adaptive

Paul Schmid-Hempel

2001-01-01

9

Host-Parasite Interaction: Parasite-Derived and -Induced Proteases That Degrade Human Extracellular Matrix  

PubMed Central

Parasitic protozoa are among the most important pathogens worldwide. Diseases such as malaria, leishmaniasis, amoebiasis, giardiasis, trichomoniasis, and trypanosomiasis affect millions of people. Humans are constantly threatened by infections caused by these pathogens. Parasites engage a plethora of surface and secreted molecules to attach to and enter mammalian cells. The secretion of lytic enzymes by parasites into host organs mediates critical interactions because of the invasion and destruction of interstitial tissues, enabling parasite migration to other sites within the hosts. Extracellular matrix is a complex, cross-linked structure that holds cells together in an organized assembly and that forms the basement membrane lining (basal lamina). The extracellular matrix represents a major barrier to parasites. Therefore, the evolution of mechanisms for connective-tissue degradation may be of great importance for parasite survival. Recent advances have been achieved in our understanding of the biochemistry and molecular biology of proteases from parasitic protozoa. The focus of this paper is to discuss the role of protozoan parasitic proteases in the degradation of host ECM proteins and the participation of these molecules as virulence factors. We divide the paper into two sections, extracellular and intracellular protozoa. PMID:22792442

Pia-Vzquez, Carolina; Reyes-Lpez, Magda; Ortz-Estrada, Guillermo; de la Garza, Mireya; Serrano-Luna, Jess

2012-01-01

10

Impact of protozoan cell death on parasite-host interactions and pathogenesis  

Microsoft Academic Search

PCD in protozoan parasites has emerged as a fascinating field of parasite biology. This not only relates to the underlying mechanisms and their evolutionary implications but also to the impact on the parasite-host interactions within mammalian hosts and arthropod vectors. During recent years, common functions of apoptosis and autophagy in protozoa and during parasitic infections have emerged. Here, we review

Carsten GK Lder; Jenny Campos-Salinas; Elena Gonzalez-Rey; Ger van Zandbergen

2010-01-01

11

Community interactions govern host-switching with implications for hostparasite coevolutionary history  

PubMed Central

Reciprocal selective effects between coevolving species are often influenced by interactions with the broader ecological community. Community-level interactions may also influence macroevolutionary patterns of coevolution, such as cospeciation, but this hypothesis has received little attention. We studied two groups of ecologically similar feather lice (Phthiraptera: Ischnocera) that differ in their patterns of association with a single group of hosts. The two groups, body lice and wing lice, are both parasites of pigeons and doves (Columbiformes). Body lice are more host-specific and show greater population genetic structure than wing lice. The macroevolutionary history of body lice also parallels that of their columbiform hosts more closely than does the evolutionary history of wing lice. The closer association of body lice with hosts, compared with wing lice, can be explained if body lice are less capable of switching hosts than wing lice. Wing lice sometimes disperse phoretically on parasitic flies (Diptera: Hippoboscidae), but body lice seldom engage in this behavior. We tested the hypothesis that wing lice switch host species more often than body lice, and that the difference is governed by phoresis. Our results show that, where flies are present, wing lice switch to novel host species in sufficient numbers to establish viable populations on the new host. Body lice do not switch hosts, even where flies are present. Thus, differences in the coevolutionary history of wing and body lice can be explained by differences in host-switching, mediated by a member of the broader parasite community. PMID:21606369

Harbison, Christopher W.; Clayton, Dale H.

2011-01-01

12

Climate impacts on landlocked sea lamprey: Implications for host-parasite interactions  

E-print Network

Climate impacts on landlocked sea lamprey: Implications for host-parasite interactions and invasive sea lamprey: Implications for host-parasite interactions and invasive species management. Ecosphere 5 profoundly shaped by exotic species. Invasion by the parasitic sea lamprey (Petromyzon marinus) contributed

Wisconsin at Madison, University of

13

Parasite Transmission in Social Interacting Hosts: Monogenean Epidemics in Guppies  

PubMed Central

Background Infection incidence increases with the average number of contacts between susceptible and infected individuals. Contact rates are normally assumed to increase linearly with host density. However, social species seek out each other at low density and saturate their contact rates at high densities. Although predicting epidemic behaviour requires knowing how contact rates scale with host density, few empirical studies have investigated the effect of host density. Also, most theory assumes each host has an equal probability of transmitting parasites, even though individual parasite load and infection duration can vary. To our knowledge, the relative importance of characteristics of the primary infected host vs. the susceptible population has never been tested experimentally. Methodology/Principal Findings Here, we examine epidemics using a common ectoparasite, Gyrodactylus turnbulli infecting its guppy host (Poecilia reticulata). Hosts were maintained at different densities (3, 6, 12 and 24 fish in 40 L aquaria), and we monitored gyrodactylids both at a population and individual host level. Although parasite population size increased with host density, the probability of an epidemic did not. Epidemics were more likely when the primary infected fish had a high mean intensity and duration of infection. Epidemics only occurred if the primary infected host experienced more than 23 worm days. Female guppies contracted infections sooner than males, probably because females have a higher propensity for shoaling. Conclusions/Significance These findings suggest that in social hosts like guppies, the frequency of social contact largely governs disease epidemics independent of host density. PMID:21897838

Johnson, Mirelle B.; Lafferty, Kevin D.; van Oosterhout, Cock; Cable, Joanne

2011-01-01

14

Genetic variation changes the interactions between the parasitic plant-ecosystem engineer Rhinanthus and its hosts  

PubMed Central

Within-species genetic variation is a potent factor influencing between-species interactions and community-level structure. Species of the hemi-parasitic plant genus Rhinanthus act as ecosystem engineers, significantly altering above- and below-ground community structure in grasslands. Here, we show the importance of genotypic variation within a single host species (barleyHordeum vulgare), and population-level variation among two species of parasite (Rhinanthus minor and Rhinanthus angustifolius) on the outcome of parasite infection for both partners. We measured host fitness (number of seeds) and calculated parasite virulence as the difference in seed set between infected and uninfected hosts (the inverse of host tolerance). Virulence was determined by genetic variation within the host species and among the parasite species, but R. angustifolius was consistently more virulent than R. minor. The most tolerant host had the lowest inherent fitness and did not gain a fitness advantage over other infected hosts. We measured parasite size as a proxy for transmission ability (ability to infect further hosts) and host resistance. Parasite size depended on the specific combination of host genotype, parasite species and parasite population, and no species was consistently larger. We demonstrate that the outcome of infection by Rhinanthus depends not only on the host species, but also on the underlying genetics of both host and parasite. Thus, genetic variations within host and parasite are probably essential components of the ecosystem-altering effects of Rhinanthus. PMID:21444312

Rowntree, Jennifer K.; Cameron, Duncan D.; Preziosi, Richard F.

2011-01-01

15

Genetic variation changes the interactions between the parasitic plant-ecosystem engineer Rhinanthus and its hosts.  

PubMed

Within-species genetic variation is a potent factor influencing between-species interactions and community-level structure. Species of the hemi-parasitic plant genus Rhinanthus act as ecosystem engineers, significantly altering above- and below-ground community structure in grasslands. Here, we show the importance of genotypic variation within a single host species (barley-Hordeum vulgare), and population-level variation among two species of parasite (Rhinanthus minor and Rhinanthus angustifolius) on the outcome of parasite infection for both partners. We measured host fitness (number of seeds) and calculated parasite virulence as the difference in seed set between infected and uninfected hosts (the inverse of host tolerance). Virulence was determined by genetic variation within the host species and among the parasite species, but R. angustifolius was consistently more virulent than R. minor. The most tolerant host had the lowest inherent fitness and did not gain a fitness advantage over other infected hosts. We measured parasite size as a proxy for transmission ability (ability to infect further hosts) and host resistance. Parasite size depended on the specific combination of host genotype, parasite species and parasite population, and no species was consistently larger. We demonstrate that the outcome of infection by Rhinanthus depends not only on the host species, but also on the underlying genetics of both host and parasite. Thus, genetic variations within host and parasite are probably essential components of the ecosystem-altering effects of Rhinanthus. PMID:21444312

Rowntree, Jennifer K; Cameron, Duncan D; Preziosi, Richard F

2011-05-12

16

Host - parasite interactions between Lernaeocera branchialis (Copepoda: Pennellidae) and its host Gadus morhua (Teleosti: Gadidae).  

E-print Network

??Abstract Lernaeocera branchialis (Linnaeus, 1767) is a parasitic copepod possessing a complex dual-host lifecycle. The definitive gadoid hosts, including Gadus morhua (Atlantic cod), Melanogrammus aeglefinus (more)

Barker, Sarah E.

2009-01-01

17

Dissecting the effect of a heterogeneous environment on the interaction between host and parasite fitness traits  

Microsoft Academic Search

Environmental variation can alter the probability of parasitic infection or the fitness consequence of infection, and thus\\u000a has the potential to dramatically alter the dynamics of host parasite coevolution. Here we investigated the effect of a changing\\u000a temperature on host-parasite interactions using the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa. By reciprocally varying (1) the temperature at which

Desiree E. Allen; Tom J. Little

2011-01-01

18

The effect of host mycorrhizal status on host plantparasitic plant interactions  

Microsoft Academic Search

Two pot experiments were conducted to examine three-level interactions between host plants, mycorrhizal fungi and parasitic\\u000a plants. In a greenhouse experiment, Poa annua plants were grown in the presence or absence of an AM fungus (either Glomus lamellosum V43a or G. mosseae BEG29) and in the presence or absence of a root hemiparasitic plant (Odontites vulgaris). In a laboratory experiment,

Veikko Salonen; Mauritz Vestberg; Marko Vauhkonen

2001-01-01

19

The Common Swift Louse Fly, Crataerina pallida: An Ideal Species for Studying Host-Parasite Interactions  

PubMed Central

Little is known of the life-history of many parasitic species. This hinders a full understanding of host-parasitic interactions. The common swift louse fly, Crataerina pallida Latreille (Diptera: Hippoboscidae), an obligate haematophagous parasite of the Common Swift, Apus apus Linnaeus 1758, is one such species. No detrimental effect of its parasitism upon the host has been found. This may be because too little is known about C. pallida ecology, and therefore detrimental effects are also unknown. This is a review of what is known about the life-history of this parasite, with the aim of promoting understanding of its ecology. New, previously unreported observations about C. pallida made from personal observations at a nesting swift colony are described. Unanswered questions are highlighted, which may aid understanding of this host-parasite system. C. pallida may prove a suitable model species for the study of other host-parasite relationships. PMID:21268705

Walker, Mark D.; Rotherham, Ian D.

2010-01-01

20

Cooperation and conflict in host manipulation: interactions among macro-parasites and micro-organisms  

PubMed Central

Several parasite species are known to manipulate the phenotype of their hosts in ways that enhance their own transmission. Co-occurrence of manipulative parasites, belonging to the same species or to more than one species, in a single host has been regularly observed. Little is known, however, on interactions between co-occurring manipulative parasites with same or different transmission routes. Several models addressing this problem have provided predictions on how cooperation and conflict between parasites could emerge from multiple infections. Here, we review the empirical evidence in favor of the existence of synergistic or antagonistic interactions between co-occurring parasites, and highlight the neglected role of micro-organisms. We particularly discuss the actual importance of selective forces shaping the evolution of interactions between manipulative parasites in relation to parasite prevalence in natural populations, efficiency in manipulation, and type of transmission (i.e., horizontal versus vertical), and we emphasize the potential for future research. PMID:24966851

Czilly, Frank; Perrot-Minnot, Marie-Jeanne; Rigaud, Thierry

2014-01-01

21

Hostparasite genotypic interactions in the honey bee: the dynamics of diversity  

PubMed Central

Parasites are thought to be a major driving force shaping genetic variation in their host, and are suggested to be a significant reason for the maintenance of sexual reproduction. A leading hypothesis for the occurrence of multiple mating (polyandry) in social insects is that the genetic diversity generated within-colonies through this behavior promotes disease resistance. This benefit is likely to be particularly significant when colonies are exposed to multiple species and strains of parasites, but hostparasite genotypic interactions in social insects are little known. We investigated this using honey bees, which are naturally polyandrous and consequently produce genetically diverse colonies containing multiple genotypes (patrilines), and which are also known to host multiple strains of various parasite species. We found that host genotypes differed significantly in their resistance to different strains of the obligate fungal parasite that causes chalkbrood disease, while genotypic variation in resistance to the facultative fungal parasite that causes stonebrood disease was less pronounced. Our results show that genetic variation in disease resistance depends in part on the parasite genotype, as well as species, with the latter most likely relating to differences in parasite life history and hostparasite coevolution. Our results suggest that the selection pressure from genetically diverse parasites might be an important driving force in the evolution of polyandry, a mechanism that generates significant genetic diversity in social insects. PMID:23919163

Evison, Sophie E F; Fazio, Geraldine; Chappell, Paula; Foley, Kirsten; Jensen, Annette B; Hughes, William O H

2013-01-01

22

Dietary supply with polyunsaturated fatty acids and resulting maternal effects influence host parasite interactions  

PubMed Central

Background Interactions between hosts and parasites can be substantially modulated by host nutrition. Polyunsaturated fatty acids (PUFAs) are essential dietary nutrients; they are indispensable as structural components of cell membranes and as precursors for eicosanoids, signalling molecules which act on reproduction and immunity. Here, we explored the potential of dietary PUFAs to affect the course of parasitic infections using a well-established invertebrate host parasite system, the freshwater herbivore Daphnia magna and its bacterial parasite Pasteuria ramosa. Results Using natural food sources differing in their PUFA composition and by experimentally modifying the availability of dietary arachidonic acid (ARA) and eicosapentaenoic acid (EPA) we examined PUFA-mediated effects resulting from direct consumption as well as maternal effects on offspring of treated mothers. We found that both host and parasite were affected by food quality. Feeding on C20 PUFA-containing food sources resulted in higher offspring production of hosts and these effects were conveyed to a great extent to the next generation. While feeding on a diet containing high PUFA concentrations significantly reduced the likelihood of becoming infected, the infection success in the next generation increased whenever the maternal diet contained PUFAs. We suggest that this opposing effect was caused by a trade-off between reproduction and immunity in the second generation. Conclusions Considering the direct and maternal effects of dietary PUFAs on host and parasite we propose that host parasite interactions and thus disease dynamics under natural conditions are subject to the availability of dietary PUFAs. PMID:24175981

2013-01-01

23

A walk on the tundra: Host-parasite interactions in an extreme environment.  

PubMed

Climate change is occurring very rapidly in the Arctic, and the processes that have taken millions of years to evolve in this very extreme environment are now changing on timescales as short as decades. These changes are dramatic, subtle and non-linear. In this article, we discuss the evolving insights into host-parasite interactions for wild ungulate species, specifically, muskoxen and caribou, in the North American Arctic. These interactions occur in an environment that is characterized by extremes in temperature, high seasonality, and low host species abundance and diversity. We believe that lessons learned in this system can guide wildlife management and conservation throughout the Arctic, and can also be generalized to more broadly understand host-parasite interactions elsewhere. We specifically examine the impacts of climate change on host-parasite interactions and focus on: (I) the direct temperature effects on parasites; (II) the importance of considering the intricacies of host and parasite ecology for anticipating climate change impacts; and (III) the effect of shifting ecological barriers and corridors. Insights gained from studying the history and ecology of host-parasite systems in the Arctic will be central to understanding the role that climate change is playing in these more complex systems. PMID:25180164

Kutz, Susan J; Hoberg, Eric P; Molnr, Pter K; Dobson, Andy; Verocai, Guilherme G

2014-08-01

24

A walk on the tundra: Hostparasite interactions in an extreme environment  

PubMed Central

Climate change is occurring very rapidly in the Arctic, and the processes that have taken millions of years to evolve in this very extreme environment are now changing on timescales as short as decades. These changes are dramatic, subtle and non-linear. In this article, we discuss the evolving insights into hostparasite interactions for wild ungulate species, specifically, muskoxen and caribou, in the North American Arctic. These interactions occur in an environment that is characterized by extremes in temperature, high seasonality, and low host species abundance and diversity. We believe that lessons learned in this system can guide wildlife management and conservation throughout the Arctic, and can also be generalized to more broadly understand hostparasite interactions elsewhere. We specifically examine the impacts of climate change on hostparasite interactions and focus on: (I) the direct temperature effects on parasites; (II) the importance of considering the intricacies of host and parasite ecology for anticipating climate change impacts; and (III) the effect of shifting ecological barriers and corridors. Insights gained from studying the history and ecology of hostparasite systems in the Arctic will be central to understanding the role that climate change is playing in these more complex systems. PMID:25180164

Kutz, Susan J.; Hoberg, Eric P.; Molnr, Pter K.; Dobson, Andy; Verocai, Guilherme G.

2014-01-01

25

Symbiotic fungal endophytes control insect host-parasite interaction webs.  

PubMed

Symbiotic microorganisms that live intimately associated with terrestrial plants affect both the quantity and quality of resources, and thus the energy supply to consumer populations at higher levels in the food chain. Empirical evidence on resource limitation of food webs points to primary productivity as a major determinant of consumer abundance and trophic structure. Prey quality plays a critical role in community regulation. Plants infected by endophytic fungi are known to be chemically protected against herbivore consumption. However, the influence of this microbe-plant association on multi-trophic interactions remains largely unexplored. Here we present the effects of fungal endophytes on insect food webs that reflect limited energy transfer to consumers as a result of low plant quality, rather than low productivity. Herbivore-parasite webs on endophyte-free grasses show enhanced insect abundance at alternate trophic levels, higher rates of parasitism, and increased dominance by a few trophic links. These results mirror predicted effects of increased productivity on food-web dynamics. Thus 'hidden' microbial symbionts can have community-wide impacts on the pattern and strength of resource-consumer interactions. PMID:11343116

Omacini, M; Chaneton, E J; Ghersa, C M; Mller, C B

2001-01-01

26

PLANT-ANIMAL INTERACTIONS -ORIGINAL PAPER Constraints on host use by a parasitic plant  

E-print Network

plant Cuscuta indecora rarely parasitizes three hosts that support vigorous growth in the greenhouse. We and select for generalized diet preferences. Keywords Cuscuta Á Host range Á Parasitic plant Á Parasitism Á

Pennings, Steven C.

27

Parasitic plants of the genus Cuscuta and their interaction with susceptible and resistant host plants  

PubMed Central

By comparison with plantmicrobe interaction, little is known about the interaction of parasitic plants with their hosts. Plants of the genus Cuscuta belong to the family of Cuscutaceae and comprise about 200 species, all of which live as stem holoparasites on other plants. Cuscuta spp. possess no roots nor fully expanded leaves and the vegetative portion appears to be a stem only. The parasite winds around plants and penetrates the host stems via haustoria, forming direct connections to the vascular bundles of their hosts to withdraw water, carbohydrates, and other solutes. Besides susceptible hosts, a few plants exist that exhibit an active resistance against infestation by Cuscuta spp. For example, cultivated tomato (Solanum lycopersicum) fends off Cuscuta reflexa by means of a hypersensitive-type response occurring in the early penetration phase. This report on the plantplant dialog between Cuscuta spp. and its host plants focuses on the incompatible interaction of C. reflexa with tomato.

Kaiser, Bettina; Vogg, Gerd; Frst, Ursula B.; Albert, Markus

2015-01-01

28

A Virus Essential for Insect Host-Parasite Interactions Encodes Cystatins  

PubMed Central

Cotesia congregata is a parasitoid wasp that injects its eggs in the host caterpillar Manduca sexta. In this host-parasite interaction, successful parasitism is ensured by a third partner: a bracovirus. The relationship between parasitic wasps and bracoviruses constitutes one of the few known mutualisms between viruses and eukaryotes. The C. congregata bracovirus (CcBV) is injected at the same time as the wasp eggs in the host hemolymph. Expression of viral genes alters the caterpillar's immune defense responses and developmental program, resulting in the creation of a favorable environment for the survival and emergence of adult parasitoid wasps. Here, we describe the characterization of a CcBV multigene family which is highly expressed during parasitism and which encodes three proteins with homology to members of the cystatin superfamily. Cystatins are tightly binding, reversible inhibitors of cysteine proteases. Other cysteine protease inhibitors have been described for lepidopteran viruses; however, this is the first description of the presence of cystatins in a viral genome. The expression and purification of a recombinant form of one of the CcBV cystatins, cystatin 1, revealed that this viral cystatin is functional having potent inhibitory activity towards the cysteine proteases papain, human cathepsins L and B and Sarcophaga cathepsin B in assays in vitro. CcBV cystatins are, therefore, likely to play a role in host caterpillar physiological deregulation by inhibiting host target proteases in the course of the host-parasite interaction. PMID:16014938

Espagne, E.; Douris, V.; Lalmanach, G.; Provost, B.; Cattolico, L.; Lesobre, J.; Kurata, S.; Iatrou, K.; Drezen, J.-M.; Huguet, E.

2005-01-01

29

A virus essential for insect host-parasite interactions encodes cystatins.  

PubMed

Cotesia congregata is a parasitoid wasp that injects its eggs in the host caterpillar Manduca sexta. In this host-parasite interaction, successful parasitism is ensured by a third partner: a bracovirus. The relationship between parasitic wasps and bracoviruses constitutes one of the few known mutualisms between viruses and eukaryotes. The C. congregata bracovirus (CcBV) is injected at the same time as the wasp eggs in the host hemolymph. Expression of viral genes alters the caterpillar's immune defense responses and developmental program, resulting in the creation of a favorable environment for the survival and emergence of adult parasitoid wasps. Here, we describe the characterization of a CcBV multigene family which is highly expressed during parasitism and which encodes three proteins with homology to members of the cystatin superfamily. Cystatins are tightly binding, reversible inhibitors of cysteine proteases. Other cysteine protease inhibitors have been described for lepidopteran viruses; however, this is the first description of the presence of cystatins in a viral genome. The expression and purification of a recombinant form of one of the CcBV cystatins, cystatin 1, revealed that this viral cystatin is functional having potent inhibitory activity towards the cysteine proteases papain, human cathepsins L and B and Sarcophaga cathepsin B in assays in vitro. CcBV cystatins are, therefore, likely to play a role in host caterpillar physiological deregulation by inhibiting host target proteases in the course of the host-parasite interaction. PMID:16014938

Espagne, E; Douris, V; Lalmanach, G; Provost, B; Cattolico, L; Lesobre, J; Kurata, S; Iatrou, K; Drezen, J-M; Huguet, E

2005-08-01

30

Interactions between environmental stressors: the influence of salinity on host-parasite interactions between Daphnia magna and Pasteuria ramosa.  

PubMed

Interactions between environmental stressors play an important role in shaping the health of an organism. This is particularly true in terms of the prevalence and severity of infectious disease, as stressors in combination will not always act to simply decrease the immune function of a host, but may instead interact to compound or even oppose the influence of parasitism on the health of an organism. Here, we explore the impact of environmental stress on host-parasite interactions using the water flea Daphnia magna and it is obligate parasite Pasteuria ramosa. Utilising an ecologically relevant stressor, we focus on the combined effect of salinity and P. ramosa on the fecundity and survival of the host, as well as on patterns of infectivity and the proliferation of the parasite. We show that in the absence of the parasite, host fecundity and survival was highest in the low salinity treatments. Once a parasite was introduced into the environment, however, salinity and parasitism acted antagonistically to influence both host survival and fecundity, and these patterns of disease were unrelated to infection rates or parasite spore loads. By summarising the form of interactions found in the broader Daphnia literature, we highlight how the combined effect of stress and parasitism will vary with the type of stressor, the trait used to describe the health of Daphnia and the host-parasite combination under observation. Our results highlight how the context-dependent nature of interactions between stress and parasitism inevitably complicates the link between environmental factors and the prevalence and severity of disease. PMID:23001624

Hall, Matthew D; Vettiger, Andrea; Ebert, Dieter

2013-04-01

31

Cerebral malaria: insights from host-parasite protein-protein interactions  

Microsoft Academic Search

BACKGROUND: Cerebral malaria is a form of human malaria wherein Plasmodium falciparum-infected red blood cells adhere to the blood capillaries in the brain, potentially leading to coma and death. Interactions between parasite and host proteins are important in understanding the pathogenesis of this deadly form of malaria. It is, therefore, necessary to study available protein-protein interactions to identify lesser known

Aditya Rao; Mayil K Kumar; Thomas Joseph; Gopalakrishnan Bulusu

2010-01-01

32

Life history determines genetic structure and evolutionary potential of hostparasite interactions  

PubMed Central

Measures of population genetic structure and diversity of disease-causing organisms are commonly used to draw inferences regarding their evolutionary history and potential to generate new variation in traits that determine interactions with their hosts. Parasite species exhibit a range of population structures and life-history strategies, including different transmission modes, life-cycle complexity, off-host survival mechanisms and dispersal ability. These are important determinants of the frequency and predictability of interactions with host species. Yet the complex causal relationships between spatial structure, life history and the evolutionary dynamics of parasite populations are not well understood. We demonstrate that a clear picture of the evolutionary potential of parasitic organisms and their demographic and evolutionary histories can only come from understanding the role of life history and spatial structure in influencing population dynamics and epidemiological patterns. PMID:18947899

Barrett, Luke G.; Thrall, Peter H.; Burdon, Jeremy J.; Linde, Celeste C.

2009-01-01

33

Relatedness and spatial proximity as determinants of host-parasite interactions in the brood parasitic Barrow's goldeneye (Bucephala islandica).  

PubMed

Recent studies, which have found evidence for kin-biased egg donation, have sparked interest in re-assessing the parasitic nature of conspecific brood parasitism (CBP). Since host-parasite kinship is essential for mutual benefits to arise from CBP, we explored the role of relatedness in determining the behaviour of conspecific nest parasites and their hosts in nesting female Barrow's goldeneyes (Bucephala islandica), a duck in which CBP is common. The results revealed that the amount of parasitism increased with host-parasite relatedness, the effect of which was independent of geographical proximity of host and parasite nests. Proximity per se was also positively associated with the amount of parasitism. Furthermore, while hosts appeared to reduce their clutch size as a response to the presence of parasitic eggs, the magnitude of host clutch reduction also tended to increase with increasing relatedness to the parasite. Hence, our results indicate that both relatedness and spatial proximity are important determinants of CBP, and that host clutch reduction may be an adaptation to nest parasitism, modulated by host-parasite relatedness. Taken together, the results provide a demonstration that relatedness influences host and parasite behaviour in Barrow's goldeneyes, resulting in kin-biased egg donation. PMID:19457174

Jaatinen, Kim; Jaari, Sonja; O'Hara, Robert B; Ost, Markus; Meril, Juha

2009-06-01

34

Betulin derivatives impair Leishmania braziliensis viability and host-parasite interaction.  

PubMed

Leishmaniasis is a public health problem in tropical and subtropical areas of the world, including Venezuela. The incidence of treatment failure and the number of cases with Leishmania-HIV co-infection underscore the importance of developing alternative, economical and effective therapies against this disease. The work presented here analyzed whether terpenoids derived from betulin are active against New World Leishmania parasites. Initially we determined the concentration that inhibits the growth of these parasites by 50% or IC50, and subsequently evaluated the chemotactic effect of four compounds with leishmanicidal activity in the sub-micromolar and micromolar range. That is, we measured the migratory capacity of Leishmania (V.) braziliensis in the presence of increasing concentrations of compounds. Finally, we evaluated their cytotoxicity against the host cell and their effect on the infectivity of L. (V.) braziliensis. The results suggest that (1) compounds 14, 17, 18, 25 and 27 are active at concentrations lower than 10?M; (2) compound 26 inhibits parasite growth with an IC50 lower than 1?M; (3) compounds 18, 26 and 27 inhibit parasite migration at pico- to nanomolar concentrations, suggesting that they impair host-parasite interaction. None of the tested compounds was cytotoxic against J774.A1 macrophages thus indicating their potential as starting points to develop compounds that might affect parasite-host cell interaction, as well as being leishmanicidal. PMID:25240731

Alcazar, Wilmer; Lpez, Adrian Silva; Alakurtti, Sami; Tuononen, Maija-Liisa; Yli-Kauhaluoma, Jari; Ponte-Sucre, Alicia

2014-11-01

35

Proceedings of the 4th International Workshop on Genetics of Host-Parasite Interactions in Forestry  

E-print Network

of resistance, and the development of molecular biology tools to assess genetic diversity and populationProceedings of the 4th International Workshop on Genetics of Host-Parasite Interactions in Forestry and Bradley I. Hillman1 Abstract Eastern filbert blight (EFB) is a devastating fungal disease of European

Standiford, Richard B.

36

Host-parasite interactions in acanthocephala: a morphological approach  

Microsoft Academic Search

In this review recent morphological and histochemical descriptions have been compiled of (mainly outer) features of all developmental stages of the Acanthocephala as well as what is known about the host's defence measures directed against these worms. From acanthors, for intance, it is documented how they escape melanization inside the haemocoel of a suitable intermediate host after they have been

Horst Taraschewski

2000-01-01

37

Phenotypic plasticity of host-parasite interactions in response to the route of infection  

Microsoft Academic Search

The microsporidium Octosporea bayeri can infect its host, the planktonic crustacean Daphnia magna, vertically and horizontally. The two routes differ greatly in the way the parasite leaves the harbouring host (transmission) and in the way it enters a new, susceptible host (infection). Infections resulting from each route may thus vary in the way they affect host and parasite life-histories and,

D. B. VIZOSO; D. EBERT

2005-01-01

38

Dual RNA-seq of Parasite and Host Reveals Gene Expression Dynamics during Filarial WormMosquito Interactions  

PubMed Central

Background Parasite biology, by its very nature, cannot be understood without integrating it with that of the host, nor can the host response be adequately explained without considering the activity of the parasite. However, due to experimental limitations, molecular studies of parasite-host systems have been predominantly one-sided investigations focusing on either of the partners involved. Here, we conducted a dual RNA-seq time course analysis of filarial worm parasite and host mosquito to better understand the parasite processes underlying development in and interaction with the host tissue, from the establishment of infection to the development of infective-stage larva. Methodology/Principal Findings Using the Brugia malayiAedes aegypti system, we report parasite gene transcription dynamics, which exhibited a highly ordered developmental program consisting of a series of cyclical and state-transitioning temporal patterns. In addition, we contextualized these parasite data in relation to the concurrent dynamics of the host transcriptome. Comparative analyses using uninfected tissues and different host strains revealed the influence of parasite development on host gene transcription as well as the influence of the host environment on parasite gene transcription. We also critically evaluated the life-cycle transcriptome of B. malayi by comparing developmental stages in the mosquito relative to those in the mammalian host, providing insight into gene expression changes underpinning the mosquito-borne parasitic lifestyle of this heteroxenous parasite. Conclusions/Significance The data presented herein provide the research community with information to design wet lab experiments and select candidates for future study to more fully dissect the whole set of molecular interactions of both organisms in this mosquito-filarial worm symbiotic relationship. Furthermore, characterization of the transcriptional program over the complete life cycle of the parasite, including stages within the mosquito, could help devise novel targets for control strategies. PMID:24853112

Mayhew, George F.; Erickson, Sara M.; Christensen, Bruce M.

2014-01-01

39

Involvement of Apoptosis in Host-Parasite Interactions in the Zebra Mussel  

PubMed Central

The question of whether cell death by apoptosis plays a biological function during infection is key to understanding host-parasite interactions. We investigated the involvement of apoptosis in several host-parasite systems, using zebra mussels Dreissena polymorpha as test organisms and their micro- and macroparasites. As a stress response associated with parasitism, heat shock proteins (Hsp) can be induced. In this protein family, Hsp70 are known to be apoptosis inhibitors. Mussels were diagnosed for their respective infections by standard histological methods; apoptosis was detected using the TUNEL methods on paraffin sections and Hsp70 by immunohistochemistry on cryosections. Circulating hemocytes were the main cells observed in apoptosis whereas infected tissues displayed no or few apoptotic cells. Parasitism by intracellular bacteria Rickettsiales-like and the trematode Bucephalus polymorphus were associated with the inhibition of apoptosis whereas ciliates Ophryoglena spp. or the trematode Phyllodistomum folium did not involve significant differences in apoptosis. Even if some parasites were able to modulate apoptosis in zebra mussels, we did not see evidence of any involvement of Hsp70 on this mechanism. PMID:23785455

Minguez, Latitia; Brul, Nelly; Sohm, Bndicte; Devin, Simon; Giambrini, Laure

2013-01-01

40

Involvement of apoptosis in host-parasite interactions in the zebra mussel.  

PubMed

The question of whether cell death by apoptosis plays a biological function during infection is key to understanding host-parasite interactions. We investigated the involvement of apoptosis in several host-parasite systems, using zebra mussels Dreissena polymorpha as test organisms and their micro- and macroparasites. As a stress response associated with parasitism, heat shock proteins (Hsp) can be induced. In this protein family, Hsp70 are known to be apoptosis inhibitors. Mussels were diagnosed for their respective infections by standard histological methods; apoptosis was detected using the TUNEL methods on paraffin sections and Hsp70 by immunohistochemistry on cryosections. Circulating hemocytes were the main cells observed in apoptosis whereas infected tissues displayed no or few apoptotic cells. Parasitism by intracellular bacteria Rickettsiales-like and the trematode Bucephalus polymorphus were associated with the inhibition of apoptosis whereas ciliates Ophryoglena spp. or the trematode Phyllodistomum folium did not involve significant differences in apoptosis. Even if some parasites were able to modulate apoptosis in zebra mussels, we did not see evidence of any involvement of Hsp70 on this mechanism. PMID:23785455

Minguez, Latitia; Brul, Nelly; Sohm, Bndicte; Devin, Simon; Giambrini, Laure

2013-01-01

41

Parasite-grass-forb interactions and rock-paper- scissor dynamics: predicting the effects of the parasitic plant Rhinanthus minor on host plant communities  

Microsoft Academic Search

Summary 1. Parasitic plants affect the growth, reproduction and metabolism of their hosts and may also influence the outcome of competitive interactions between host species and, consequently, the struc- ture of entire host communities. 2. We investigate the effect of the root hemiparasitic plant Rhinanthus minor on plant community dynamics using a spatial theoretical model. The model is parameterized with

Duncan D. Cameron; Andy White; Janis Antonovics

2009-01-01

42

Spatial heterogeneity, frequency-dependent selection and polymorphism in host-parasite interactions  

PubMed Central

Background Genomic and pathology analysis has revealed enormous diversity in genes involved in disease, including those encoding host resistance and parasite effectors (also known in plant pathology as avirulence genes). It has been proposed that such variation may persist when an organism exists in a spatially structured metapopulation, following the geographic mosaic of coevolution. Here, we study gene-for-gene relationships governing the outcome of plant-parasite interactions in a spatially structured system and, in particular, investigate the population genetic processes which maintain balanced polymorphism in both species. Results Following previous theory on the effect of heterogeneous environments on maintenance of polymorphism, we analysed a model with two demes in which the demes have different environments and are coupled by gene flow. Environmental variation is manifested by different coefficients of natural selection, the costs to the host of resistance and to the parasite of virulence, the cost to the host of being diseased and the cost to an avirulent parasite of unsuccessfully attacking a resistant host. We show that migration generates negative direct frequency-dependent selection, a condition for maintenance of stable polymorphism in each deme. Balanced polymorphism occurs preferentially if there is heterogeneity for costs of resistance and virulence alleles among populations and to a lesser extent if there is variation in the cost to the host of being diseased. We show that the four fitness costs control the natural frequency of oscillation of host resistance and parasite avirulence alleles. If demes have different costs, their frequencies of oscillation differ and when coupled by gene flow, there is amplitude death of the oscillations in each deme. Numerical simulations show that for a multiple deme island model, costs of resistance and virulence need not to be present in each deme for stable polymorphism to occur. Conclusions Our theoretical results confirm the importance of empirical studies for measuring the environmental heterogeneity for genetic costs of resistance and virulence alleles. We suggest that such studies should be developed to investigate the generality of this mechanism for the long-term maintenance of genetic diversity at host and parasite genes. PMID:22044632

2011-01-01

43

Assessing the Effects of Climate on Host-Parasite Interactions: A Comparative Study of European Birds and Their Parasites  

PubMed Central

Background Climate change potentially has important effects on distribution, abundance, transmission and virulence of parasites in wild populations of animals. Methodology/Principal Finding Here we analyzed paired information on 89 parasite populations for 24 species of bird hosts some years ago and again in 2010 with an average interval of 10 years. The parasite taxa included protozoa, feather parasites, diptera, ticks, mites and fleas. We investigated whether change in abundance and prevalence of parasites was related to change in body condition, reproduction and population size of hosts. We conducted analyses based on the entire dataset, but also on a restricted dataset with intervals between study years being 515 years. Parasite abundance increased over time when restricting the analyses to datasets with an interval of 515 years, with no significant effect of changes in temperature at the time of breeding among study sites. Changes in host body condition and clutch size were related to change in temperature between first and second study year. In addition, changes in clutch size, brood size and body condition of hosts were correlated with change in abundance of parasites. Finally, changes in population size of hosts were not significantly related to changes in abundance of parasites or their prevalence. Conclusions/Significance Climate change is associated with a general increase in parasite abundance. Variation in laying date depended on locality and was associated with latitude while body condition of hosts was associated with a change in temperature. Because clutch size, brood size and body condition were associated with change in parasitism, these results suggest that parasites, perhaps mediated through the indirect effects of temperature, may affect fecundity and condition of their hosts. The conclusions were particularly in accordance with predictions when the restricted dataset with intervals of 515 years was used, suggesting that short intervals may bias findings. PMID:24391725

Mller, Anders Pape; Merino, Santiago; Soler, Juan Jos; Antonov, Anton; Bads, Elisa P.; Calero-Torralbo, Miguel A.; de Lope, Florentino; Eeva, Tapio; Figuerola, Jordi; Flensted-Jensen, Einar; Garamszegi, Laszlo Z.; Gonzlez-Braojos, Sonia; Gwinner, Helga; Hanssen, Sveinn Are; Heylen, Dieter; Ilmonen, Petteri; Klarborg, Kurt; Korpimki, Erkki; Martnez, Javier; Martnez-de la Puente, Josue; Marzal, Alfonso; Matthysen, Erik; Matyjasiak, Piotr; Molina-Morales, Mercedes; Moreno, Juan; Mousseau, Timothy A.; Nielsen, Jan Tttrup; Pap, Pter Lszl; Rivero-de Aguilar, Juan; Shurulinkov, Peter; Slagsvold, Tore; Szp, Tibor; Szll?si, Eszter; Trk, Janos; Vaclav, Radovan; Valera, Francisco; Ziane, Nadia

2013-01-01

44

Resolving the infection process reveals striking differences in the contribution of environment, genetics and phylogeny to host-parasite interactions  

Microsoft Academic Search

BackgroundInfection processes consist of a sequence of steps, each critical for the interaction between host and parasite. Studies of\\u000a host-parasite interactions rarely take into account the fact that different steps might be influenced by different factors\\u000a and might, therefore, make different contributions to shaping coevolution. We designed a new method using the Daphnia magna - Pasteuria ramosa system, one of

David Duneau; Pepijn Luijckx; Frida Ben-Ami; Christian Laforsch; Dieter Ebert

2011-01-01

45

Large, rapidly evolving gene families are at the forefront of host-parasite interactions in Apicomplexa.  

PubMed

SUMMARY The Apicomplexa is a phylum of parasitic protozoa, which includes the malaria parasite Plasmodium, amongst other species that can devastate human and animal health. The past decade has seen the release of genome sequences for many of the most important apicomplexan species, providing an excellent basis for improving our understanding of their biology. One of the key features of each genome is a unique set of large, variant gene families. Although closely related species share the same families, even different types of malaria parasite have distinct families. In some species they tend to be found at the ends of chromosomes, which may facilitate aspects of gene expression regulation and generation of sequence diversity. In others they are scattered apparently randomly across chromosomes. For some families there is evidence they are involved in antigenic variation, immune regulation and immune evasion. For others there are no known functions. Even where function is unknown these families are most often predicted to be exposed to the host, contain much sequence diversity and evolve rapidly. Based on these properties it is clear that they are at the forefront of host-parasite interactions. In this review I compare and contrast the genomic context, gene structure, gene expression, protein localization and function of these families across different species. PMID:25257746

Reid, Adam J

2015-02-01

46

Landscape heterogeneity shapes host-parasite interactions and results in apparent plant-virus codivergence.  

PubMed

Knowledge on how landscape heterogeneity shapes host-parasite interactions is central to understand the emergence, dynamics and evolution of infectious diseases. However, this is an underexplored subject, particularly for plant-virus systems. Here, we analyse how landscape heterogeneity influences the prevalence, spatial genetic structure, and temporal dynamics of Pepper golden mosaic and Pepper huasteco yellow vein begomoviruses infecting populations of the wild pepper Capsicum annuum glabriusculum (chiltepin) in Mexico. Environmental heterogeneity occurred at different nested spatial scales (host populations within biogeographical provinces), with levels of human management varying among host population within a province. Results indicate that landscape heterogeneity affects the epidemiology and genetic structure of chiltepin-infecting begomoviruses in a scale-specific manner, probably related to conditions favouring the viruses' whitefly vector and its dispersion. Increased levels of human management of the host populations were associated with higher virus prevalence and erased the spatial genetic structure of the virus populations. Also, environmental heterogeneity similarly shaped the spatial genetic structures of host and viruses. This resulted in the congruence between host and virus phylogenies, which does not seem to be due to host-virus co-evolution. Thus, results provide evidence of the key role of landscape heterogeneity in determining plant-virus interactions. PMID:23379795

Rodelo-Urrego, M; Pagn, I; Gonzlez-Jara, P; Betancourt, M; Moreno-Letelier, A; Aylln, M A; Fraile, A; Piero, D; Garca-Arenal, F

2013-04-01

47

Control strategies for a stochastic model of host-parasite interaction in a seasonal environment.  

PubMed

We examine a nonlinear stochastic model for the parasite load of a single host over a predetermined time interval. We use nonhomogeneous Poisson processes to model the acquisition of parasites, the parasite-induced host mortality, the natural (no parasite-induced) host mortality, and the reproduction and death of parasites within the host. Algebraic results are first obtained on the age-dependent distribution of the number of parasites infesting the host at an arbitrary time t. The interest is in control strategies based on isolation of the host and the use of an anthelmintic at a certain intervention instant t0. This means that the host is free living in a seasonal environment, and it is transferred to a uninfected area at age t0. In the uninfected area, the host does not acquire new parasites, undergoes a treatment to decrease the parasite load, and its natural and parasite-induced mortality are altered. For a suitable selection of t0, we present two control criteria that appropriately balance effectiveness and cost of intervention. Our approach is based on simple probabilistic principles, and it allows us to examine seasonal fluctuations of gastrointestinal nematode burden in growing lambs. PMID:24657746

Gmez-Corral, A; Lpez Garca, M

2014-08-01

48

Long live the Red Queen? Examining environmental influences on host-parasite interactions in Daphnia.  

E-print Network

mutagen ENU and investigated the impact of the parasite Pasteuria ramosa on mutation load under different of certain P. ramosa strains to infect their hosts is affected by prior host exposure to different strains

West, Stuart

49

Cloning of the unculturable parasite Pasteuria ramosa and its Daphnia host reveals extreme genotype-genotype interactions.  

PubMed

The degree of specificity in host-parasite interactions has important implications for ecology and evolution. Unfortunately, specificity can be difficult to determine when parasites cannot be cultured. In such cases, studies often use isolates of unknown genetic composition, which may lead to an underestimation of specificity. We obtained the first clones of the unculturable bacterium Pasteuria ramosa, a parasite of Daphnia magna. Clonal genotypes of the parasite exhibited much more specific interactions with host genotypes than previous studies using isolates. Clones of P. ramosa infected fewer D. magna genotypes than isolates and host clones were either fully susceptible or fully resistant to the parasite. Our finding enhances our understanding of the evolution of virulence and coevolutionary dynamics in this system. We recommend caution when using P. ramosa isolates as the presence of multiple genotypes may influence the outcome and interpretation of some experiments. PMID:21091597

Luijckx, Pepijn; Ben-Ami, Frida; Mouton, Laurence; Du Pasquier, Louis; Ebert, Dieter

2011-02-01

50

HOST-PARASITE AND GENOTYPE-BY-ENVIRONMENT INTERACTIONS: TEMPERATURE MODIFIES POTENTIAL FOR SELECTION BY A STERILIZING PATHOGEN  

Microsoft Academic Search

Parasite-mediated selection is potentially of great importance in modulating genetic diversity. Genetic variation for resistance, the fuel for natural selection, appears to be common in host-parasite interactions, but responses to selection are rarely observed. In the present study, we tested whether environmental variation could mediate infection and determine evolutionary outcomes. Temperature was shown to dramatically alter the potential for parasite-mediated

Suzanne E. Mitchell; Emily S. Rogers; Tom J. Little; Andrew F. Read

2005-01-01

51

Interactions between frequency-dependent and vertical transmission in host-parasite systems.  

PubMed Central

We investigate host-pathogen dynamics and conditions for coexistence in two models incorporating frequency-dependent horizontal transmission in conjunction with vertical transmission. The first model combines frequency-dependent and uniparental vertical transmission, while the second addresses parasites transmitted vertically via both parents. For the first model, we ask how the addition of vertical transmission changes the coexistence criteria for parasites transmitted by a frequency-dependent horizontal route, and show that vertical transmission significantly broadens the conditions for parasite invasion. Host-parasite coexistence is further affected by the form of density-dependent host regulation. Numerical analyses demonstrate that within a host population, a parasite strain with horizontal frequency-dependent transmission can be driven to extinction by a parasite strain that is additionally transmitted vertically for a wide range of parameters. Although models of asexual host populations predict that vertical transmission alone cannot maintain a parasite over time, analysis of our second model shows that vertical transmission via both male and female parents can maintain a parasite at a stable equilibrium. These results correspond with the frequent co-occurrence of vertical with sexual transmission in nature and suggest that these transmission modes can lead to host-pathogen coexistence for a wide range of systems involving hosts with high reproductive rates. PMID:9265188

Altizer, S M; Augustine, D J

1997-01-01

52

Synergistic parasite-pathogen interactions mediated by host immunity can drive the collapse of honeybee colonies.  

PubMed

The health of the honeybee and, indirectly, global crop production are threatened by several biotic and abiotic factors, which play a poorly defined role in the induction of widespread colony losses. Recent descriptive studies suggest that colony losses are often related to the interaction between pathogens and other stress factors, including parasites. Through an integrated analysis of the population and molecular changes associated with the collapse of honeybee colonies infested by the parasitic mite Varroa destructor, we show that this parasite can de-stabilise the within-host dynamics of Deformed wing virus (DWV), transforming a cryptic and vertically transmitted virus into a rapidly replicating killer, which attains lethal levels late in the season. The de-stabilisation of DWV infection is associated with an immunosuppression syndrome, characterized by a strong down-regulation of the transcription factor NF-?B. The centrality of NF-?B in host responses to a range of environmental challenges suggests that this transcription factor can act as a common currency underlying colony collapse that may be triggered by different causes. Our results offer an integrated account for the multifactorial origin of honeybee losses and a new framework for assessing, and possibly mitigating, the impact of environmental challenges on honeybee health. PMID:22719246

Nazzi, Francesco; Brown, Sam P; Annoscia, Desiderato; Del Piccolo, Fabio; Di Prisco, Gennaro; Varricchio, Paola; Della Vedova, Giorgio; Cattonaro, Federica; Caprio, Emilio; Pennacchio, Francesco

2012-01-01

53

Synergistic Parasite-Pathogen Interactions Mediated by Host Immunity Can Drive the Collapse of Honeybee Colonies  

PubMed Central

The health of the honeybee and, indirectly, global crop production are threatened by several biotic and abiotic factors, which play a poorly defined role in the induction of widespread colony losses. Recent descriptive studies suggest that colony losses are often related to the interaction between pathogens and other stress factors, including parasites. Through an integrated analysis of the population and molecular changes associated with the collapse of honeybee colonies infested by the parasitic mite Varroa destructor, we show that this parasite can de-stabilise the within-host dynamics of Deformed wing virus (DWV), transforming a cryptic and vertically transmitted virus into a rapidly replicating killer, which attains lethal levels late in the season. The de-stabilisation of DWV infection is associated with an immunosuppression syndrome, characterized by a strong down-regulation of the transcription factor NF-?B. The centrality of NF-?B in host responses to a range of environmental challenges suggests that this transcription factor can act as a common currency underlying colony collapse that may be triggered by different causes. Our results offer an integrated account for the multifactorial origin of honeybee losses and a new framework for assessing, and possibly mitigating, the impact of environmental challenges on honeybee health. PMID:22719246

Nazzi, Francesco; Brown, Sam P.; Annoscia, Desiderato; Del Piccolo, Fabio; Di Prisco, Gennaro; Varricchio, Paola; Della Vedova, Giorgio; Cattonaro, Federica; Caprio, Emilio; Pennacchio, Francesco

2012-01-01

54

Resolving the infection process reveals striking differences in the contribution of environment, genetics and phylogeny to host-parasite interactions  

PubMed Central

Background Infection processes consist of a sequence of steps, each critical for the interaction between host and parasite. Studies of host-parasite interactions rarely take into account the fact that different steps might be influenced by different factors and might, therefore, make different contributions to shaping coevolution. We designed a new method using the Daphnia magna - Pasteuria ramosa system, one of the rare examples where coevolution has been documented, in order to resolve the steps of the infection and analyse the factors that influence each of them. Results Using the transparent Daphnia hosts and fluorescently-labelled spores of the bacterium P. ramosa, we identified a sequence of infection steps: encounter between parasite and host; activation of parasite dormant spores; attachment of spores to the host; and parasite proliferation inside the host. The chances of encounter had been shown to depend on host genotype and environment. We tested the role of genetic and environmental factors in the newly described activation and attachment steps. Hosts of different genotypes, gender and species were all able to activate endospores of all parasite clones tested in different environments; suggesting that the activation cue is phylogenetically conserved. We next established that parasite attachment occurs onto the host oesophagus independently of host species, gender and environmental conditions. In contrast to spore activation, attachment depended strongly on the combination of host and parasite genotypes. Conclusions Our results show that different steps are influenced by different factors. Host-type-independent spore activation suggests that this step can be ruled out as a major factor in Daphnia-Pasteuria coevolution. On the other hand, we show that the attachment step is crucial for the pronounced genetic specificities of this system. We suggest that this one step can explain host population structure and could be a key force behind coevolutionary cycles. We discuss how different steps can explain different aspects of the coevolutionary dynamics of the system: the properties of the attachment step, explaining the rapid evolution of infectivity and the properties of later parasite proliferation explaining the evolution of virulence. Our study underlines the importance of resolving the infection process in order to better understand host-parasite interactions. PMID:21342515

2011-01-01

55

Host Sexual Dimorphism and Parasite Adaptation  

PubMed Central

In species with separate sexes, parasite prevalence and disease expression is often different between males and females. This effect has mainly been attributed to sex differences in host traits, such as immune response. Here, we make the case for how properties of the parasites themselves can also matter. Specifically, we suggest that differences between host sexes in many different traits, such as morphology and hormone levels, can impose selection on parasites. This selection can eventually lead to parasite adaptations specific to the host sex more commonly encountered, or to differential expression of parasite traits depending on which host sex they find themselves in. Parasites adapted to the sex of the host in this way can contribute to differences between males and females in disease prevalence and expression. Considering those possibilities can help shed light on hostparasite interactions, and impact epidemiological and medical science. PMID:22389630

Duneau, David; Ebert, Dieter

2012-01-01

56

Host-parasite and genotype-by-environment interactions: temperature modifies potential for selection by a sterilizing pathogen.  

PubMed

Parasite-mediated selection is potentially of great importance in modulating genetic diversity. Genetic variation for resistance, the fuel for natural selection, appears to be common in host-parasite interactions, but responses to selection are rarely observed. In the present study, we tested whether environmental variation could mediate infection and determine evolutionary outcomes. Temperature was shown to dramatically alter the potential for parasite-mediated selection in two independent laboratory infection experiments at four temperatures. The bacterial parasite, Pasteuria ramosa, was extremely virulent at 20 degrees C and 25 degrees C, sterilizing its host, Daphnia magna, so that females often never produced a single brood. However, at 10 degrees C and 15 degrees C, the host-parasite interaction was much more benign, as nearly all females produced broods before becoming sterile. This association between virulence and temperature alone could stabilize coexistence and lead to the maintenance of diversity, because it would weaken parasite-mediated selection during parts of the season. Additionally, highly significant genotype-by-environment interactions were found, with changes in clone rank order for infection rates at different temperatures. Our results clearly show that the outcome of parasite-mediated selection in this system is strongly context dependent. PMID:15792228

Mitchell, Suzanne E; Rogers, Emily S; Little, Tom J; Read, Andrew F

2005-01-01

57

Do Antioxidants Play a Role in Schistosome HostParasite Interactions?  

Microsoft Academic Search

Schistosoma mansoni, an intravascular parasite, lives in a hostile environment in close contact with host humoral and cellular cytotoxic factors. To establish itself in the host, the schistosome has evolved a number of immune evasion mechanisms. Here, Philip LoVerde discusses evidence suggesting that antioxidant enzymes provide one such mechanism used by adult schistosomes. Antioxidant enzymes may thus represent a target

P. T LoVerde

1998-01-01

58

Insights into the Trypanosome-Host Interactions Revealed through Transcriptomic Analysis of Parasitized Tsetse Fly Salivary Glands  

PubMed Central

The agents of sleeping sickness disease, Trypanosoma brucei complex parasites, are transmitted to mammalian hosts through the bite of an infected tsetse. Information on tsetse-trypanosome interactions in the salivary gland (SG) tissue, and on mammalian infective metacyclic (MC) parasites present in the SG, is sparse. We performed RNA-seq analyses from uninfected and T. b. brucei infected SGs of Glossina morsitans morsitans. Comparison of the SG transcriptomes to a whole body fly transcriptome revealed that only 2.7% of the contigs are differentially expressed during SG infection, and that only 263 contigs (0.6%) are preferentially expressed in the SGs (SG-enriched). The expression of only 37 contigs (0.08%) and 27 SG-enriched contigs (10%) were suppressed in infected SG. These suppressed contigs accounted for over 55% of the SG transcriptome, and included the most abundant putative secreted proteins with anti-hemostatic functions present in saliva. In contrast, expression of putative host proteins associated with immunity, stress, cell division and tissue remodeling were enriched in infected SG suggesting that parasite infections induce host immune and stress response(s) that likely results in tissue renewal. We also performed RNA-seq analysis from mouse blood infected with the same parasite strain, and compared the transcriptome of bloodstream form (BSF) cells with that of parasites obtained from the infected SG. Over 30% of parasite transcripts are differentially regulated between the two stages, and reflect parasite adaptations to varying host nutritional and immune ecology. These differences are associated with the switch from an amino acid based metabolism in the SG to one based on glucose utilization in the blood, and with surface coat modifications that enable parasite survival in the different hosts. This study provides a foundation on the molecular aspects of the trypanosome dialogue with its tsetse and mammalian hosts, necessary for future functional investigations. PMID:24763140

Zhao, Xin; Savage, Amy F.; Regmi, Sandesh; e Silva, Thiago Luiz Alves; O'Neill, Michelle; Aksoy, Serap

2014-01-01

59

Haemonchus contortus P-Glycoproteins Interact with Host Eosinophil Granules: A Novel Insight into the Role of ABC Transporters in Host-Parasite Interaction  

PubMed Central

Eosinophils are one of the major mammalian effector cells encountered by helminths during infection. In the present study, we investigated the effects of eosinophil granule exposure on the sheep parasitic nematode Haemonchus contortus as a model. H. contortus eggs exposed to eosinophil granule products showed increased rhodamine 123 efflux and this effect was not due to loss of egg integrity. Rh123 is known to be a specific P-glycoprotein (Pgp) substrate and led to the hypothesis that in addition to their critical role in xenobiotic resistance, helminth ABC transporters such as Pgp may also be involved in the detoxification of host cytotoxic products. We showed by quantitative RT-PCR that, among nine different H. contortus Pgp genes, Hco-pgp-3, Hco-pgp-9.2, Hco-pgp-11 and, Hco-pgp-16 were specifically up-regulated in parasitic life stages suggesting a potential involvement of these Pgps in the detoxification of eosinophil granule products. Using exsheathed L3 larvae that mimic the first life stage in contact with the host, we demonstrated that eosinophil granules induced a dose dependent overexpression of Hco-pgp-3 and the closely related Hco-pgp-16. Taken together, our results provide the first evidence that a subset of helminth Pgps interact with, and could be involved in the detoxification of, host products. This opens the way for further studies aiming to explore the role of helminth Pgps in the host-parasite interaction, including evasion of the host immune response. PMID:24498376

Issouf, Mohamed; Gugnard, Fabrice; Koch, Christine; Le Vern, Yves; Blanchard-Letort, Alexandra; Che, Hua; Beech, Robin N.; Kerboeuf, Dominique; Neveu, Cedric

2014-01-01

60

Getting What Is Served? Feeding Ecology Influencing Parasite-Host Interactions in Invasive Round Goby Neogobius melanostomus  

PubMed Central

Freshwater ecosystems are increasingly impacted by alien invasive species which have the potential to alter various ecological interactions like predator-prey and host-parasite relationships. Here, we simultaneously examined predator-prey interactions and parasitization patterns of the highly invasive round goby (Neogobius melanostomus) in the rivers Rhine and Main in Germany. A total of 350 N. melanostomus were sampled between June and October 2011. Gut content analysis revealed a broad prey spectrum, partly reflecting temporal and local differences in prey availability. For the major food type (amphipods), species compositions were determined. Amphipod fauna consisted entirely of non-native species and was dominated by Dikerogammarus villosus in the Main and Echinogammarus trichiatus in the Rhine. However, the availability of amphipod species in the field did not reflect their relative abundance in gut contents of N. melanostomus. Only two metazoan parasites, the nematode Raphidascaris acus and the acanthocephalan Pomphorhynchus sp., were isolated from N. melanostomus in all months, whereas unionid glochidia were only detected in June and October in fish from the Main. To analyse infection pathways, we examined 17,356 amphipods and found Pomphorhynchus sp. larvae only in D. villosus in the river Rhine at a prevalence of 0.15%. Dikerogammarus villosus represented the most important amphipod prey for N. melanostomus in both rivers but parasite intensities differed between rivers, suggesting that final hosts (large predatory fishes) may influence host-parasite dynamics of N. melanostomus in its introduced range. PMID:25338158

Emde, Sebastian; Kochmann, Judith; Kuhn, Thomas; Plath, Martin; Klimpel, Sven

2014-01-01

61

Controlled Chaos of Polymorphic Mucins in a Metazoan Parasite (Schistosoma mansoni) Interacting with Its Invertebrate Host (Biomphalaria glabrata)  

PubMed Central

Invertebrates were long thought to possess only a simple, effective and hence non-adaptive defence system against microbial and parasitic attacks. However, recent studies have shown that invertebrate immunity also relies on immune receptors that diversify (e.g. in echinoderms, insects and mollusks (Biomphalaria glabrata)). Apparently, individual or population-based polymorphism-generating mechanisms exists that permit the survival of invertebrate species exposed to parasites. Consequently, the generally accepted arms race hypothesis predicts that molecular diversity and polymorphism also exist in parasites of invertebrates. We investigated the diversity and polymorphism of parasite molecules (Schistosoma mansoni Polymorphic Mucins, SmPoMucs) that are key factors for the compatibility of schistosomes interacting with their host, the mollusc Biomphalaria glabrata. We have elucidated the complex cascade of mechanisms acting both at the genomic level and during expression that confer polymorphism to SmPoMuc. We show that SmPoMuc is coded by a multi-gene family whose members frequently recombine. We show that these genes are transcribed in an individual-specific manner, and that for each gene, multiple splice variants exist. Finally, we reveal the impact of this polymorphism on the SmPoMuc glycosylation status. Our data support the view that S. mansoni has evolved a complex hierarchical system that efficiently generates a high degree of polymorphisma controlled chaosbased on a relatively low number of genes. This contrasts with protozoan parasites that generate antigenic variation from large sets of genes such as Trypanosoma cruzi, Trypanosoma brucei and Plasmodium falciparum. Our data support the view that the interaction between parasites and their invertebrate hosts are far more complex than previously thought. While most studies in this matter have focused on invertebrate host diversification, we clearly show that diversifying mechanisms also exist on the parasite side of the interaction. Our findings shed new light on how and why invertebrate immunity develops. PMID:19002242

Roger, Emmanuel; Grunau, Christoph; Pierce, Raymond J.; Hirai, Hirohisa; Gourbal, Benjamin; Galinier, Richard; Emans, Rmi; Cesari, Italo M.; Cosseau, Cline; Mitta, Guillaume

2008-01-01

62

To eject or to abandon? Life history traits of hosts and parasites interact to influence the fitness payoffs of alternative anti-parasite strategies.  

PubMed

Hosts either tolerate avian brood parasitism or reject it by ejecting parasitic eggs, as seen in most rejecter hosts of common cuckoos, Cuculus canorus, or by abandoning parasitized clutches, as seen in most rejecter hosts of brown-headed cowbirds, Molothrus ater. What explains consistent variation between alternative rejection behaviours of hosts within the same species and across species when exposed to different types of parasites? Life history theory predicts that when parasites decrease the fitness of host offspring, but not the future reproductive success of host adults, optimal clutch size should decrease. Consistent with this prediction, evolutionarily old cowbird hosts, but not cuckoo hosts, have lower clutch sizes than related rarely- or newly parasitized species. We constructed a mathematical model to calculate the fitness payoffs of egg ejector vs. nest abandoner hosts to determine if various aspects of host life history traits and brood parasites' virulence on adult and young host fitness differentially influence the payoffs of alternative host defences. These calculations showed that in general egg ejection was a superior anti-parasite strategy to nest abandonment. Yet, increasing parasitism rates and increasing fitness values of hosts' eggs in both currently parasitized and future replacement nests led to switch points in fitness payoffs in favour of nest abandonment. Nonetheless, nest abandonment became selectively more favourable only at lower clutch sizes and only when hosts faced parasitism by a cowbird- rather than a cuckoo-type brood parasite. We suggest that, in addition to evolutionary lag and gape-size limitation, our estimated fitness differences based on life history trait variation provide new insights for the consistent differences observed in the anti-parasite rejection strategies between many cuckoo- and cowbird-hosts. PMID:16910987

Servedio, M R; Hauber, M E

2006-09-01

63

Urbanization Breaks Up Host-Parasite Interactions: A Case Study on Parasite Community Ecology of Rufous-Bellied Thrushes (Turdus rufiventris) along a Rural-Urban Gradient  

PubMed Central

Urbanization drastically alters natural ecosystems and the structure of their plant and animal communities. Whereas some species cope successfully with these environmental changes, others may go extinct. In the case of parasite communities, the expansion of urban areas has a critical effect by changing the availability of suitable substrates for the eggs or free-larval stages of those species with direct life cycles or for the range of hosts of those species with complex cycles. In this study we investigated the influence of the degree of urbanization and environmental heterogeneity on helminth richness, abundance and community structure of rufous-bellied thrushes (Turdus rufiventris) along a rural-urban gradient in the metropolitan region of Porto Alegre, State of Rio Grande do Sul, Brazil. This common native bird species of southern Brazil hosts 15 endoparasite species at the study region. A total of 144 thrushes were collected with mist nets at 11 sites. The degree of urbanization and environmental heterogeneity were estimated by quantifying five landscape elements: buildings, woodlands, fields, bare lands, and water. Landscape analyses were performed at two spatial scales (10 and 100 ha) taking into account home range size and the potential dispersal distance of thrushes and their prey (intermediate hosts). Mean parasite richness showed an inverse relationship with the degree of urbanization, but a positive relationship with environmental heterogeneity. Changes in the structure of component communities along the rural-urban gradient resulted from responses to the availability of particular landscape elements that are compatible with the parasites' life cycles. We found that the replacement of natural environments with buildings breaks up host-parasite interactions, whereas a higher environmental (substrate) diversity allows the survival of a wider range of intermediate hosts and vectors and their associated parasites. PMID:25068271

Calegaro-Marques, Cludia; Amato, Suzana B.

2014-01-01

64

Outcomes of Brood ParasiteHost Interactions Mediated by Egg Matching: Common Cuckoos Cuculus canorus versus Fringilla Finches  

PubMed Central

Background Antagonistic species often interact via matching of phenotypes, and interactions between brood parasitic common cuckoos (Cuculus canorus) and their hosts constitute classic examples. The outcome of a parasitic event is often determined by the match between host and cuckoo eggs, giving rise to potentially strong associations between fitness and egg phenotype. Yet, empirical efforts aiming to document and understand the resulting evolutionary outcomes are in short supply. Methods/Principal Findings We used avian color space models to analyze patterns of egg color variation within and between the cuckoo and two closely related hosts, the nomadic brambling (Fringilla montifringilla) and the site fidelic chaffinch (F. coelebs). We found that there is pronounced opportunity for disruptive selection on brambling egg coloration. The corresponding cuckoo host race has evolved egg colors that maximize fitness in both sympatric and allopatric brambling populations. By contrast, the chaffinch has a more bimodal egg color distribution consistent with the evolutionary direction predicted for the brambling. Whereas the brambling and its cuckoo host race show little geographical variation in their egg color distributions, the chaffinch's distribution becomes increasingly dissimilar to the brambling's distribution towards the core area of the brambling cuckoo host race. Conclusion High rates of brambling gene flow is likely to cool down coevolutionary hot spots by cancelling out the selection imposed by a patchily distributed cuckoo host race, thereby promoting a matching equilibrium. By contrast, the site fidelic chaffinch is more likely to respond to selection from adapting cuckoos, resulting in a markedly more bimodal egg color distribution. The geographic variation in the chaffinch's egg color distribution could reflect a historical gradient in parasitism pressure. Finally, marked cuckoo egg polymorphisms are unlikely to evolve in these systems unless the hosts evolve even more exquisite egg recognition capabilities than currently possessed. PMID:21559400

Vikan, Johan Reinert; Fossy, Frode; Huhta, Esa; Moksnes, Arne; Rskaft, Eivin; Stokke, Brd Gunnar

2011-01-01

65

Calcium signaling during the plant-plant interaction of parasitic Cuscuta reflexa with its hosts  

PubMed Central

The plant parasite Cuscuta reflexa induces various responses in compatible and incompatible host plants. The visual reactions of both types of host plants including obvious morphological changes require the recognition of Cuscuta ssp. A consequently initiated signaling cascade is triggered which leads to a tolerance of the infection or, in the case of some incompatible host plants, to resistance. Calcium (Ca2+) release is the major second messenger during signal transduction. Therefore, we have studied Ca2+ spiking in tomato and tobacco during infection with C. reflexa. In our recently published study1 Ca2+ signals were monitored as bioluminescence in aequorin-expressing tomato plants after the onset of C. reflexa infestation. Signals at the attachment sites were observed from 30 to 48 h after infection. In an assay with leaf disks of aequorin-expressing tomato which were treated with different C. reflexa plant extracts it turned out that the substance that induced Ca2+ release in the host plant was closely linked to the parasite's haustoria. PMID:20818172

Kaiser, Bettina; van der Krol, Sander; Kaldenhoff, Ralf

2010-01-01

66

Calcium signaling during the plant-plant interaction of parasitic Cuscuta reflexa with its hosts.  

PubMed

The plant parasite Cuscuta reflexa induces various responses in compatible and incompatible host plants. The visual reactions of both types of host plants including obvious morphological changes require the recognition of Cuscuta ssp. A consequently initiated signaling cascade is triggered which leads to a tolerance of the infection or, in the case of some incompatible host plants, to resistance. Calcium (Ca(2+)) release is the major second messenger during signal transduction. Therefore, we have studied Ca(2+) spiking in tomato and tobacco during infection with C. reflexa. In our recently published study Ca(2+) signals were monitored as bioluminescence in aequorin-expressing tomato plants after the onset of C. reflexa infestation. Signals at the attachment sites were observed from 30 to 48 h after infection. In an assay with leaf disks of aequorin-expressing tomato which were treated with different C. reflexa plant extracts it turned out that the substance that induced Ca(2+) release in the host plant was closely linked to the parasite's haustoria. PMID:20818172

Albert, Markus; Kaiser, Bettina; van der Krol, Sander; Kaldenhoff, Ralf

2010-09-01

67

Differential host defense against multiple parasites in ants  

Microsoft Academic Search

Hostparasite interactions are ideal systems for the study of coevolutionary processes. Although infections with multiple\\u000a parasite species are presumably common in nature, most studies focus on the interactions of a single host and a single parasite.\\u000a To the best of our knowledge, we present here the first study on the dependency of parasite virulence and host resistance\\u000a in a multiple

Christoph von Beeren; Munetoshi Maruyama; Rosli Hashim; Volker Witte

2011-01-01

68

Genome sequencing and comparative genomics of honey bee microsporidia, Nosema apis reveal novel insights into host-parasite interactions  

PubMed Central

Background The microsporidia parasite Nosema contributes to the steep global decline of honey bees that are critical pollinators of food crops. There are two species of Nosema that have been found to infect honey bees, Nosema apis and N. ceranae. Genome sequencing of N. apis and comparative genome analysis with N. ceranae, a fully sequenced microsporidia species, reveal novel insights into host-parasite interactions underlying the parasite infections. Results We applied the whole-genome shotgun sequencing approach to sequence and assemble the genome of N. apis which has an estimated size of 8.5 Mbp. We predicted 2,771 protein- coding genes and predicted the function of each putative protein using the Gene Ontology. The comparative genomic analysis led to identification of 1,356 orthologs that are conserved between the two Nosema species and genes that are unique characteristics of the individual species, thereby providing a list of virulence factors and new genetic tools for studying host-parasite interactions. We also identified a highly abundant motif in the upstream promoter regions of N. apis genes. This motif is also conserved in N. ceranae and other microsporidia species and likely plays a role in gene regulation across the microsporidia. Conclusions The availability of the N. apis genome sequence is a significant addition to the rapidly expanding body of microsprodian genomic data which has been improving our understanding of eukaryotic genome diversity and evolution in a broad sense. The predicted virulent genes and transcriptional regulatory elements are potential targets for innovative therapeutics to break down the life cycle of the parasite. PMID:23829473

2013-01-01

69

Clinical heterogeneity of human neurocysticercosis results from complex interactions among parasite, host and environmental factors.  

PubMed

Human neurocysticercosis (NC) is endemic in most countries of Latin America, Asia and Africa and is re-emerging in some industrialized nations. Both within and among endemic countries, NC is very variable in its clinical and radiological features, as well as in the intensity of the immuno-inflammatory reactions of the hosts. This review, focusing on the Mexican experience, describes and interprets the heterogeneity of NC as the result of different combinations among factors associated with the parasite, host and environment. The review may serve to foster similar descriptive efforts in other endemic areas of the world in order to facilitate the identification of the distinct factors that participate in the complex pathogenesis and diverse clinical outcomes of NC. In particular, it is necessary to understand the precise physiopathology of the inflammatory reaction associated with NC, as inflammation is one of the characteristics of those NC cases that are clinically more severe and less responsive to current treatments. Devising new medical interventions through the use of molecular regulators of the innate and adaptive immune responses of the host is a largely unexplored approach that could improve the existing forms of treatment. PMID:20116079

Fleury, Agns; Escobar, Alfonso; Fragoso, Gladis; Sciutto, Edda; Larralde, Carlos

2010-04-01

70

Parasitic infection reduces dispersal of ciliate host  

PubMed Central

Parasitic infection can modify host mobility and consequently their dispersal capacity. We experimentally investigated this idea using the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata. We compared the short-distance dispersal of infected and uninfected populations in interconnected microcosms. Infection reduced the proportion of hosts dispersing, with levels differing among host clones. Host populations with higher densities showed lower dispersal, possibly owing to social aggregation behaviour. Parasite isolates that depleted host populations most had the lowest impact on host dispersal. Parasite-induced modification of dispersal may have consequences for the spatial distribution of disease, host and parasite genetic population structure, and coevolution. PMID:20961885

Fellous, Simon; Quillery, Elsa; Duncan, Alison B.; Kaltz, Oliver

2011-01-01

71

HOST-PARASITE INTERACTIONS ON AN EXPERIMENTAL LANDSCAPE KARL L. KOSCIUCH  

E-print Network

anti- parasite defense behaviors, and parasitism by Brown-headed Cowbirds (Molothrus ater) may cause by Brown-headed Cowbirds (Molothrus ater) may cause population declines in some species. Bell's Vireo

Sandercock, Brett K.

72

Fate of Parasite and Host Organelle DNA during Cellular Transformation of Red Algae by Their Parasites.  

PubMed Central

The transfer of a nucleus into a cytoplasm of a genetically foreign cell and its subsequent multiplication in the cytoplasm of this cell characterize most parasitic red algal species and their interactions with specific red algal hosts. Nuclei enter the host's cytoplasm upon cell fusion of parasite and host cell; here, they replicate, are spread to contiguous host cells, and ultimately are packaged into spores that reinfect other host thalli. In this study, we examined whether the proplastids and mitochondria that occur in these red algal adelphoparasites are acquired from their host or whether they are unique to the parasite and are brought into the host along with the parasite nucleus. To establish their origins and fates, plastid and mitochondrial restriction fragment length polymorphisms (RFLPs) of parasite cells were compared with those of their host plastid and mitochondrial DNA in three host and parasite pairs. For plastids, no RFLP differences were found between hosts and parasites, supporting an earlier conclusion, based on microscopic studies, that the proplastids of parasites are acquired from their hosts. For mitochondria, characteristic RFLP differences were detected between host and parasite for two of the pairs of species but not for the third. Evidence of the evolutionary difference between hosts and their parasites was shown by RFLP differences between nuclear ribosomal repeat regions. PMID:12242362

Goff, L. J.; Coleman, A. W.

1995-01-01

73

Molecular analysis of predation on parasitized hosts.  

PubMed

Predation on parasitized hosts can significantly affect natural enemy communities, and such intraguild predation may indirectly affect control of herbivore populations. However, the methodological challenges for studying these often complex trophic interactions are formidable. Here, we evaluate a DNA-based approach to track parasitism and predation on parasitized hosts in model herbivore-parasitoid-predator systems. Using singleplex polymerase chain reaction (SP-PCR) to target mtDNA of the parasitoid only, and multiplex PCR (MP-PCR) to additionally target host DNA as an internal amplification control, we found that detection of DNA from the parasitoid, Lysiphlebus testaceipes, in its aphid host, Aphis fabae, was possible as early as 5 min. post parasitism. Up to 24 h post parasitism SP-PCR proved to be more sensitive than MP-PCR in amplifying parasitoid DNA. In the carabid beetles Demetrias atricapillus and Erigone sp. spiders, fed with aphids containing five-day-old parasitoids, parasitoid and aphid DNA were equally detectable in both predator groups. However, when hosts containing two-day-old parasitoids were fed to the predators, detection of parasitoid prey was possible only at 0 h (immediately after consumption) and up to 8 h post consumption in carabids and spiders, respectively. Over longer periods of time, post-feeding prey detection success was significantly higher in spiders than in carabid beetles. MP-PCR, in which parasitoid and aphid DNA were simultaneously amplified, proved to be less sensitive at amplifying prey DNA than SP-PCR. In conclusion, our study demonstrates that PCR-based parasitoid and prey detection offers an exciting approach to further our understanding of host-parasitoid-predator interactions. PMID:18439340

Traugott, M; Symondson, W O C

2008-06-01

74

Host social behavior and parasitic infection: A multifactorial approach  

USGS Publications Warehouse

I examined associations between several components of host social organization, including group size and gregariousness, group stability, territoriality and social class, and gastrointestinal parasite load in African bovids. At an intraspecific level, group size was positively correlated with parasite prevalence, but only when the parasite was relatively host specific and only among host species living in stable groups. Social class was also an important predictor of infection rates. Among gazelles, territorial males had higher parasite intensities than did either bachelor males or females and juveniles, suggesting that highly territorial individuals may be either more exposed or more susceptible to parasites. Associations among territoriality, grouping, and parasitism were also found across taxa. Territorial host genera were more likely to be infected with strongyle nematodes than were nonterritorial hosts, and gregarious hosts were more infected than were solitary hosts. Analyses also revealed that gregariousness and territoriality had an interactive effect on individual parasite richness, whereby hosts with both traits harbored significantly more parasite groups than did hosts with only one or neither trait. Overall, study results indicate that multiple features of host social behavior influence infection risk and suggest that synergism between traits also has important effects on host parasite load.

Ezenwa, V.O.

2004-01-01

75

Plastic behaviors in hosts promote the emergence of retaliatory parasites  

PubMed Central

Mafia like behavior, where individuals cooperate under the threat of punishment, occurs not only in humans, but is also observed in several animal species. Observations suggest that avian hosts tend to accept a certain degree of parasitism in order to avoid retaliating punishment from the brood parasite. To understand under which conditions it will be beneficial for a host to cooperate, we model the interaction between hosts and parasites as an evolutionary game. In our model, the host's behavior is plastic, and thus, its response depends on the previous interactions with the parasite. We find that such learned behavior in turn is crucial for the evolution of retaliating parasites. The abundance of this kind of mafia behavior oscillates in time and does not settle to an equilibrium. Our results suggest that retaliation is a mechanism for the parasite to evade specialization and to induce acceptance by the host. PMID:24589512

Chakra, Maria Abou; Hilbe, Christian; Traulsen, Arne

2014-01-01

76

Evolution of host specificity in monogeneans parasitizing African cichlid fish  

PubMed Central

Background The patterns and processes linked to the host specificity of parasites represent one of the central themes in the study of host-parasite interactions. We investigated the evolution and determinants of host specificity in gill monogeneans of Cichlidogyrus and Scutogyrus species parasitizing African freshwater fish of Cichlidae. Methods We analyzed (1) the link between host specificity and parasite phylogeny, (2) potential morphometric correlates of host specificity (i.e. parasite body size and the morphometrics of the attachment apparatus), and (3) potential determinants of host specificity following the hypothesis of ecological specialization and the hypothesis of specialization on predictable resources (i.e. host body size and longevity were considered as measures of host predictability), and (4) the role of brooding behavior of cichlids in Cichlidogyrus and Scutogyrus diversification. Results No significant relationships were found between host specificity and phylogeny of Cichlidogyrus and Scutogyrus species. The mapping of host specificity onto the parasite phylogenetic tree revealed that an intermediate specialist parasitizing congeneric cichlid hosts represents the ancestral state for the Cichlidogyrus/Scutogyrus group. Only a weak relationship was found between the morphometry of the parasites attachment apparatus and host specificity. Our study did not support the specialization on predictable resources or ecological specialization hypotheses. Nevertheless, host specificity was significantly related to fish phylogeny and form of parental care. Conclusions Our results confirm that host specificity is not a derived condition for Cichlidogyrus/Scutogyrus parasites and may reflect other than historical constraints. Attachment apparatus morphometry reflects only partially (if at all) parasite adaptation to the host species, probably because of the morphological similarity of rapidly evolved cichlids (analyzed in our study). However, we showed that parental care behavior of cichlids may play an important role linked to host specificity of Cichlidogyrus/Scutogyrus parasites. PMID:24529542

2014-01-01

77

Multitrophic interaction facilitates parasite-host relationship between an invasive beetle and the honey bee.  

PubMed

Colony defense by honey bees, Apis mellifera, is associated with stinging and mass attack, fueled by the release of alarm pheromones. Thus, alarm pheromones are critically important to survival of honey bee colonies. Here we report that in the parasitic relationship between the European honey bee and the small hive beetle, Aethina tumida, the honey bee's alarm pheromones serve a negative function because they are potent attractants for the beetle. Furthermore, we discovered that the beetles from both Africa and the United States vector a strain of Kodamaea ohmeri yeast, which produces these same honey bee alarm pheromones when grown on pollen in hives. The beetle is not a pest of African honey bees because African bees have evolved effective methods to mitigate beetle infestation. However, European honey bees, faced with disease and pest management stresses different from those experienced by African bees, are unable to effectively inhibit beetle infestation. Therefore, the environment of the European honey bee colony provides optimal conditions to promote the unique bee-beetle-yeast-pollen multitrophic interaction that facilitates effective infestation of hives at the expense of the European honey bee. PMID:17483478

Torto, Baldwyn; Boucias, Drion G; Arbogast, Richard T; Tumlinson, James H; Teal, Peter E A

2007-05-15

78

Host Behavior Manipulation by Parasitic Insects and Insect Parasites  

Microsoft Academic Search

Insects and parasites are ubiquitous. In any environment, there are numerous insects and parasites. Independent evolutionary selection has occurred and parasites and insects are taxonomically diverse (Roy et al, 2006). However, many insect-parasite interacts have evolved between insects and parasites due to the number and habitat overlap of the groups (Roy et al, 2006). In addition, to the separation of

Rustie Robison

79

Implications of bioactive solute transfer from hosts to parasitic plants.  

PubMed

Parasitic plants--which make their living by extracting nutrients and other resources from other plants--are important components of many natural ecosystems; and some parasitic species are also devastating agricultural pests. To date, most research on plant parasitism has focused on nutrient transfer from host to parasite and the impacts of parasites on host plants. Far less work has addressed potential effects of the translocation of bioactive non-nutrient solutes-such as phytohormones, secondary metabolites, RNAs, and proteins-on the development and physiology of parasitic plants and on their subsequent interactions with other organisms such as insect herbivores. A growing number of recent studies document the transfer of such molecules from hosts to parasites and suggest that they may have significant impacts on parasite physiology and ecology. We review this literature and discuss potential implications for management and priorities for future research. PMID:23870786

Smith, Jason D; Mescher, Mark C; De Moraes, Consuelo M

2013-08-01

80

Understanding the interaction between an obligate hyperparasitic bacterium, Pasteuria penetrans and its obligate plant-parasitic nematode host, Meloidogyne spp.  

PubMed

Pasteuria penetrans is an endospore-forming bacterium, which is a hyperparasite of root-knot nematodes Meloidogyne spp. that are economically important pests of a wide range of crops. The life cycle of the bacterium and nematode are described with emphasis on the bacterium's potential as a biocontrol agent. Two aspects that currently prohibit the commercial development of the bacterium as a biocontrol agent are the inability to culture it outside its host and its host specificity. Vegetative growth of the bacterium is possible in vitro; however, getting the vegetative stages of the bacterium to enter sporogenesis has been problematic. Insights from genomic survey sequences regarding the role of cation concentration and the phosphorylation of Spo0F have proved useful in inducing vegetative bacteria to sporulate. Similarly, genomic data have also proved useful in understanding the attachment of endospores to the cuticle of infective nematode juveniles, and a Velcro-like model of spore attachment is proposed that involves collagen-like fibres on the surface of the endospore interacting with mucins on the nematode cuticle. Ecological studies of the interactions between Daphnia and Pasteuria ramosa are examined and similarities are drawn between the co-evolution of virulence in the Daphnia system and that of plant-parasitic nematodes. PMID:19289196

Davies, Keith G

2009-01-01

81

Host-Apicomplexan Parasite Interactions: Leveraging Biological Discovery Into Antiparasitic Drug Development.  

E-print Network

??The obligate intracellular pathogens Plasmodium falciparum and Toxoplasma gondii remodel their host cell to facilitate their intracellular development and progress through their asexual life cycle, (more)

Millholland, Melanie Grace

2013-01-01

82

Host and parasite diversity jointly control disease risk in complex communities  

E-print Network

Host and parasite diversity jointly control disease risk in complex communities Pieter T. J, Berkeley, CA, and approved September 10, 2013 (received for review June 3, 2013) Host­parasite interactions parasites. To date, however, surprisingly few studies have explored the joint effects of host and parasite

Johnson, Pieter

83

Parasite-host interactions between the Varroa mite and the honey bee  

Microsoft Academic Search

Introduction<\\/h3>

Varroa mites as parasites of honey bees<\\/h4>Varroa destructor (Anderson & Trueman, 2000), is the most important pest of European races of the Western honey bee, Apis mellifera L., weakening bees and vectoring bee diseases (Matheson, 1993). Over the past decades it has spread all over the world and control measures are required to maintain healthy honey bee colonies.Originally, this mite

J. N. M. Calis

2001-01-01

84

Parasite-host interaction in malaria: genetic clues and copy number variation  

Microsoft Academic Search

In humans, infections contribute highly to mortality and morbidity rates worldwide. Malaria tropica is one of the major infectious\\u000a diseases globally and is caused by the protozoan parasite Plasmodium falciparum. Plasmodia have accompanied human beings since the emergence of humankind. Due to its pathogenicity, malaria is a powerful\\u000a selective force on the human genome. Genetic epidemiology approaches such as family

Imad Faik; Elisandra Grangeiro de Carvalho; Jrgen FJ Kun

2009-01-01

85

PARASITE-HOST SPECIFICITY: EXPERIMENTAL STUDIES ON THE BASIS OF PARASITE ADAPTATION  

Microsoft Academic Search

Abstract. Specificity in parasitic interactions can be defined,by host genotypes,that are resistant to only a subset of parasite genotypes,and parasite genotypes,that are infective on a subset of host genotypes. It is not always,clear if specificity is determined by the genotypes of the interactors, or if phenotypic plasticity (sometimes called acclimation) plays a larger role. Coevolutionary outcomes,critically depend,on the pervasiveness,of genetic

Tom J. Little; Kathryn Watt; Dieter Ebert

2006-01-01

86

Within-Host Speciation of Malaria Parasites  

PubMed Central

Background Sympatric speciationthe divergence of populations into new species in absence of geographic barriers to hybridizationis the most debated mode of diversification of life forms. Parasitic organisms are prominent models for sympatric speciation, because they may colonise new hosts within the same geographic area and diverge through host specialization. However, it has been argued that this mode of parasite divergence is not strict sympatric speciation, because host shifts likely cause the sudden effective isolation of parasites, particularly if these are transmitted by vectors and therefore cannot select their hosts. Strict sympatric speciation would involve parasite lineages diverging within a single host species, without any population subdivision. Methodology/Principal Findings Here we report a case of extraordinary divergence of sympatric, ecologically distinct, and reproductively isolated malaria parasites within a single avian host species, which apparently occurred without historical or extant subdivision of parasite or host populations. Conclusions/Significance This discovery of within-host speciation changes our current view on the diversification potential of malaria parasites, because neither geographic isolation of host populations nor colonization of new host species are any longer necessary conditions to the formation of new parasite species. PMID:17311104

Prez-Tris, Javier; Hellgren, Olof; Krianauskien?, Asta; Waldenstrm, Jonas; Secondi, Jean; Bonneaud, Camille; Fjelds, Jon; Hasselquist, Dennis; Bensch, Staffan

2007-01-01

87

Proceedings of the 4th International Workshop on Genetics of Host-Parasite Interactions in Forestry  

E-print Network

of resistance becomes essential. Combinations or "pyramids" of major genes can greatly increase durability of resistance and have provided some major success stories in annual crops. The mechanisms by which pyramids about selection for "superraces" in host mixtures has likely been greatly overstated, and the mechanisms

Standiford, Richard B.

88

Repeated targeting of the same hosts by a brood parasite compromises host egg rejection  

PubMed Central

Cuckoo eggs famously mimic those of their foster parents to evade rejection from discriminating hosts. Here we test whether parasites benefit by repeatedly parasitizing the same host nest. This should make accurate rejection decisions harder, regardless of the mechanism that hosts use to identify foreign eggs. Here we find strong support for this prediction in the African tawny-flanked prinia (Prinia subflava), the most common host of the cuckoo finch (Anomalospiza imberbis). We show experimentally that hosts reject eggs that differ from an internal template, but crucially, as the proportion of foreign eggs increases, hosts are less likely to reject them and require greater differences in appearance to do so. Repeated parasitism by the same cuckoo finch female is common in host nests and likely to be an adaptation to increase the probability of host acceptance. Thus, repeated parasitism interacts with egg mimicry to exploit cognitive and sensory limitations in host defences. PMID:24064931

Stevens, Martin; Troscianko, Jolyon; Spottiswoode, Claire N.

2013-01-01

89

Host range and local parasite adaptation.  

PubMed Central

Parasites may be expected to become locally adapted to their hosts. However, while many empirical studies have demonstrated local parasite adaptation, others have failed to demonstrate it, or have shown local parasite maladaptation. Researchers have suggested that gene flow can swamp local parasite-host dynamics and produce local adaptation only at certain geographical scales; others have argued that evolutionary lags can account for both null and maladaptive results. In this paper, we use item response theory (IRT) to test whether host range influences the likelihood of parasites locally adapting to their hosts. We collated 32 independent experiments testing for local adaptation, where parasites could be assigned as having either broad or narrow host ranges (BHR and NHR, respectively). Twenty-five tests based on BHR parasites had a significantly lower average effect size than seven NHR tests, indicating that studies based on BHR parasites are less likely to demonstrate local parasite adaptation. We argue that this may relate to evolutionary lags during diffuse coevolution of BHR parasites with their hosts, rather than differences in experimental approaches or other confounds between BHR and NHR studies. PMID:11934361

Lajeunesse, Marc J; Forbes, Mark R

2002-01-01

90

Parasite predators exhibit a rapid numerical response to increased parasite abundance and reduce transmission to hosts  

PubMed Central

Predators of parasites have recently gained attention as important parts of food webs and ecosystems. In aquatic systems, many taxa consume free-living stages of parasites, and can thus reduce parasite transmission to hosts. However, the importance of the functional and numerical responses of parasite predators to disease dynamics is not well understood. We collected hostparasitepredator cooccurrence data from the field, and then experimentally manipulated predator abundance, parasite abundance, and the presence of alternative prey to determine the consequences for parasite transmission. The parasite predator of interest was a ubiquitous symbiotic oligochaete of mollusks, Chaetogaster limnaei limnaei, which inhabits host shells and consumes larval trematode parasites. Predators exhibited a rapid numerical response, where predator populations increased or decreased by as much as 60% in just 5 days, depending on the parasite:predator ratio. Furthermore, snail infection decreased substantially with increasing parasite predator densities, where the highest predator densities reduced infection by up to 89%. Predators of parasites can play an important role in regulating parasite transmission, even when infection risk is high, and especially when predators can rapidly respond numerically to resource pulses. We suggest that these types of interactions might have cascading effects on entire disease systems, and emphasize the importance of considering disease dynamics at the community level. PMID:24340184

Hopkins, Skylar R; Wyderko, Jennie A; Sheehy, Robert R; Belden, Lisa K; Wojdak, Jeremy M

2013-01-01

91

Plant Host Finding by Parasitic Plants  

PubMed Central

Plants release airborne chemicals that can convey ecologically relevant information to other organisms. These plant volatiles are known to mediate a large array of, often complex, interactions between plants and insects. It has been suggested that plant volatiles may have similar importance in mediating interactions among plant species, but there are few well-documented examples of plant-to-plant communication via volatiles, and the ecological significance of such interactions has been much debated. To date, nearly all studies of volatile-mediated interactions among plant species have focused on the reception of herbivore-induced volatiles by neighboring plants. We recently documented volatile effects in another system, demonstrating that the parasitic plant Cuscuta pentagona uses volatile cues to locate its hosts. This finding may broaden the discussion regarding plant-to-plant communication, and suggests that new classes of volatile-meditated interactions among plant species await discovery. PMID:19704627

Mescher, Mark C; Runyon, Justin B

2006-01-01

92

Effects of salinity on an intertidal hostparasite system: Is the parasite more sensitive than its host?  

E-print Network

Effects of salinity on an intertidal host­parasite system: Is the parasite more sensitive than its Host­parasite interaction Parasitism Salinity Transmission Trematoda Intertidal habitats are characterised by highly fluctuating environmental conditions including varying salinity regimes. Changes

Poulin, Robert

93

Ecto-ATPase activity on the surface of Trypanosoma cruzi and its possible role in the parasitehost cell interaction  

Microsoft Academic Search

This study describes the possible role of Mg 2+-dependent ecto-ATPase activity on the Trypanosoma cruzihost cell interaction. Mg 2+-dependent ecto-ATPase activity is observed on the cell body and flagellar membranes of the parasite and is about 20times greater in trypomastigotes, as compared with epimastigotes. Suramin (a competitive antagonist of P2 receptors) and the impermeant agent 4,4'-diisothiocyanostylbene 2',2'-disulfonic acid (DIDS), both

Danielle F. R. Bisaggio; CarlosEduardo Peres-Sampaio; JosRoberto Meyer-Fernandes; Thas Souto-Padrn

2003-01-01

94

Parasite-host specificity: experimental studies on the basis of parasite adaptation.  

PubMed

Specificity in parasitic interactions can be defined by host genotypes that are resistant to only a subset of parasite genotypes and parasite genotypes that are infective on a subset of host genotypes. It is not always clear if specificity is determined by the genotypes of the interactors, or if phenotypic plasticity (sometimes called acclimation) plays a larger role. Coevolutionary outcomes critically depend on the pervasiveness of genetic interactions. We studied specificity using the bacterial parasite Pasteuria ramosa and its crustacean host Daphnia magna. First, we tested for short-term adaptation of P. ramosa lines that had been rapidly shifted among different host genotypes. Adaptation at this time-scale would demonstrate the contribution of phenotypic plasticity to specificity. We found that infectivity was stable across lines irrespective of recent passage history, indicating that in the short term infection outcomes are fixed by genetic backgrounds. Second, we studied longer-term evolution with two host clones and two parasite lines. In this experiment, P. ramosa lines had the possibility to evolve adaptations to the host genotype (clone) in which they were serially passaged, which allowed us to test for a genetic component to specificity. Substantial differences arose in the two passaged lines: one parasite line gained infectivity on the host clone it was grown on, but it lost infectivity on the other host genotype (this line evolved specificity), while the other parasite line evolved higher infectivity on both host clones. We crossed the two host genotypes used in the serial passage experiment and found evidence that the number of host genes that underlies resistance variation is small. In sum, our results show that P. ramosa specificity is a stably inherited trait, it can evolve rapidly, and it is controlled by few genes in the host. These findings are consistent with the idea of a rapid, ongoing arms race between the bacterium and its host. PMID:16568629

Little, Tom J; Watt, Kathryn; Ebert, Dieter

2006-01-01

95

Thiacloprid-Nosema ceranae interactions in honey bees: host survivorship but not parasite reproduction is dependent on pesticide dose.  

PubMed

Interactions between stressors contribute to the recently reported increase in losses of honey bee colonies. Here we demonstrated that a synergistic effect on mortality by the low toxic, commonly used neonicotinoid thiacloprid and the nearly ubiquitous gut parasite Nosemaceranae is dependent on the pesticide dose. Furthermore, thiacloprid had a negative influence on N.ceranae reproduction. Our results highlight that interactions among honey bee health stressors can be dynamic and should be studied across a broader range of combinations. PMID:24594300

Retschnig, Gina; Neumann, Peter; Williams, Geoffrey R

2014-05-01

96

Differential reproductive success favours strong host preference in a highly specialized brood parasite.  

PubMed

Obligate avian brood parasites show dramatic variation in the degree to which they are host specialists or host generalists. The screaming cowbird Molothrus rufoaxillaris is one of the most specialized brood parasites, using a single host, the bay-winged cowbird (Agelaioides badius) over most of its range. Coevolutionary theory predicts increasing host specificity the longer the parasite interacts with a particular avian community, as hosts evolve defences that the parasite cannot counteract. According to this view, host specificity can be maintained if screaming cowbirds avoid parasitizing potentially suitable hosts that have developed effective defences against parasitic females or eggs. Specialization may also be favoured, even in the absence of host defences, if the parasite's reproductive success in alternative hosts is lower than that in the main host. We experimentally tested these hypotheses using as alternative hosts two suitable but unparasitized species: house wrens (Troglodytes aedon) and chalk-browed mockingbirds (Mimus saturninus). We assessed host defences against parasitic females and eggs, and reproductive success of the parasite in current and alternative hosts. Alternative hosts did not discriminate against screaming cowbird females or eggs. Egg survival and hatching success were similarly high in current and alternative hosts, but the survival of parasitic chicks was significantly lower in alternative hosts. Our results indicate that screaming cowbirds have the potential to colonize novel hosts, but higher reproductive success in the current host may favour host fidelity. PMID:18647716

De Mrsico, Mara C; Reboreda, Juan C

2008-11-01

97

Differential reproductive success favours strong host preference in a highly specialized brood parasite  

PubMed Central

Obligate avian brood parasites show dramatic variation in the degree to which they are host specialists or host generalists. The screaming cowbird Molothrus rufoaxillaris is one of the most specialized brood parasites, using a single host, the bay-winged cowbird (Agelaioides badius) over most of its range. Coevolutionary theory predicts increasing host specificity the longer the parasite interacts with a particular avian community, as hosts evolve defences that the parasite cannot counteract. According to this view, host specificity can be maintained if screaming cowbirds avoid parasitizing potentially suitable hosts that have developed effective defences against parasitic females or eggs. Specialization may also be favoured, even in the absence of host defences, if the parasite's reproductive success in alternative hosts is lower than that in the main host. We experimentally tested these hypotheses using as alternative hosts two suitable but unparasitized species: house wrens (Troglodytes aedon) and chalk-browed mockingbirds (Mimus saturninus). We assessed host defences against parasitic females and eggs, and reproductive success of the parasite in current and alternative hosts. Alternative hosts did not discriminate against screaming cowbird females or eggs. Egg survival and hatching success were similarly high in current and alternative hosts, but the survival of parasitic chicks was significantly lower in alternative hosts. Our results indicate that screaming cowbirds have the potential to colonize novel hosts, but higher reproductive success in the current host may favour host fidelity. PMID:18647716

De Mrsico, Mara C; Reboreda, Juan C

2008-01-01

98

Increasing productivity accelerates hostparasite coevolution  

Microsoft Academic Search

Host-parasite coevolution is believed to influence a range of evolutionary and ecological processes, including population dynamics, evolution of diversity, sexual reproduction and parasite virulence. The impact of coevolution on these processes will depend on its rate, which is likely to be affected by the energy flowing through an ecosystem, or productivity. We addressed how productivity affected rates of coevolution during

L. d. C. LOPEZ-PASCUA; A. BUCKLING

2008-01-01

99

Development of Some Larval Nematodes in Experimental and Natural Animal Hosts: An Insight into Development of Pathological Lesions vis-a-vis Host-Parasite Interactions  

PubMed Central

Infective third-stage larvae of three spiruroid nematodes, Ascarops strongylina and Physocephalus sexalatus of pigs and Spirocerca lupi of dogs, were recovered from 14 species of coprophagous beetles belonging to 4 different genera. These larvae were fed to rabbits and/or guinea pigs to study their development in these experimental hosts. Larvae of A. strongylina reached the adult stage in all rabbits and one guinea pig. The adult worms recovered in these hosts were 40% and 4%, respectively, and became diminutive in comparison to their natural hosts. The larvae of P. sexalatus became reencysted in the gastric wall of rabbits inducing marked pathological changes. The infective larvae of S. lupi became reencapsulated in the stomach wall of the rabbit and also showed development in the aortic wall. Adults of Toxocara canis of dog, collected from 5 different regions of the Indian subcontinent, varied significantly in size. The mouse passage of infective larvae of one of these types led to the recovery of the adults from the experimental dogs that were smaller in size and caused severe pathology in natural experimental hosts. Developmental effects shown in experimental hosts and host specificity are of value in understanding the evolution of nematode parasitism. PMID:24453801

Chowdhury, N.; Sood, N. K.; Lal, Shyam; Gupta, Kuldip; Singla, L. D.

2013-01-01

100

Host-parasite coevolution: Insights from the Daphnia-parasite model system.  

PubMed

Daphnia and its parasites have become recognized as a model system for studying the epidemiological, evolutionary and genetic interactions between hosts and parasites. The key advantages of the Daphnia-parasite system are the propagation of the host as iso-female lines, that is clonal, but at the same time the possibility to cross lines. Furthermore, Daphnia have diverse parasites, including bacteria, fungi, microsporidia and helminths, which can be kept in culture with the hosts. For two parasites of Daphnia magna, coevolution has been demonstrated phenotypically. Coevolution in D. magna and the bacterium Pasteuria ramosa is consistent with model predictions of coevolution by negative frequency dependent selection, the Red Queen hypothesis. The genetic mechanisms have not yet been elucidated. PMID:18556238

Ebert, Dieter

2008-06-01

101

Genetic variation in a host-parasite association: potential for coevolution and frequency-dependent selection.  

PubMed

Models of host-parasite coevolution assume the presence of genetic variation for host resistance and parasite infectivity, as well as genotype-specific interactions. We used the freshwater crustacean Daphnia magna and its bacterial microparasite Pasteuria ramosa to study genetic variation for host susceptibility and parasite infectivity within each of two populations. We sought to answer the following questions: Do host clones differ in their susceptibility to parasite isolates? Do parasite isolates differ in their ability to infect different host clones? Are there host clone-parasite isolate interactions? The analysis revealed considerable variation in both host resistance and parasite infectivity. There were significant host clone-parasite isolate interactions, such that there was no single host clone that was superior to all other clones in the resistance to every parasite isolate. Likewise, there was no parasite isolate that was superior to all other isolates in infectivity to every host clone. This form of host clone-parasite isolate interaction indicates the potential for coevolution based on frequency-dependent selection. Infection success of original host clone-parasite isolate combinations (i.e., those combinations that were isolated together) was significantly higher than infection success of novel host clone-parasite isolate combinations (i.e., those combinations that were created in the laboratory). This finding is consistent with the idea that parasites track specific host genotypes under natural conditions. In addition, correspondence analysis revealed that some host clones, although distinguishable with neutral genetic markers, were susceptible to the same set of parasite isolates and thus probably shared resistance genes. PMID:11475049

Carius, H J; Little, T J; Ebert, D

2001-06-01

102

Constraints on host use by a parasitic plant  

Microsoft Academic Search

Consumers do not always utilize all suitable hosts. Understanding why parasitic plants do not always parasitize potentially\\u000a suitable hosts requires a better understanding of the constraints that limit host use by parasitic plants. In Texas salt marshes,\\u000a the parasitic plant Cuscuta indecora rarely parasitizes three hosts that support vigorous growth in the greenhouse. We identified three constraints on host use

Emily S. Marquardt; Steven C. Pennings

2010-01-01

103

Variation for host range within and among populations of the parasitic plant Striga hermonthica  

PubMed Central

Striga hermonthica is an angiosperm parasite that causes substantial damage to a wide variety of cereal crop species, and to the livelihoods of subsistence farmers in sub-Saharan Africa. The broad host range of this parasite makes it a fascinating model for the study of hostparasite interactions, and suggests that effective long-term control strategies for the parasite will require an understanding of the potential for host range adaptation in parasite populations. We used a controlled experiment to test the extent to which the success or failure of S. hermonthica parasites to develop on a particular host cultivar (host resistance/compatibility) depends upon the identity of interacting host genotypes and parasite populations. We also tested the hypothesis that there is a genetic component to host range within individual S. hermonthica populations, using three rice cultivars with known, contrasting abilities to resist infection. The developmental success of S. hermonthica parasites growing on different rice-host cultivars (genotypes) depended significantly on a parasite population by hostgenotype interaction. Genetic analysis using amplified fragment length polymorphism (AFLP) markers revealed that a small subset of AFLP markers showed outlier' genetic differentiation among sub-populations of S. hermonthica attached to different host cultivars. We suggest that, this indicates a genetic component to host range within populations of S. hermonthica, and that a detailed understanding of the genomic loci involved will be crucial in understanding hostparasite specificity and in breeding crop cultivars with broad spectrum resistance to S. hermonthica. PMID:21731054

Huang, K; Whitlock, R; Press, M C; Scholes, J D

2012-01-01

104

Evolution of parasite virulence against qualitative or quantitative host resistance  

E-print Network

Evolution of parasite virulence against qualitative or quantitative host resistance Sylvain Gandon¡ects of two di¡erent modes of host resistance on the evolution of parasite virulence. Hosts can either adopt of resistance (i.e. which reduces the within-host growth rate of the parasite). We show that the mode of host

105

Host genetics and parasitic infections.  

PubMed

Parasites still impose a high death and disability burden on human populations, and are therefore likely to act as selective factors for genetic adaptations. Genetic epidemiological investigation of parasitic diseases is aimed at disentangling the mechanisms underlying immunity and pathogenesis by looking for associations or linkages between loci and susceptibility phenotypes. Until recently, most studies used a candidate gene approach and were relatively underpowered, with few attempts at replicating findings in different populations. However, in the last 5years, genome-wide and/or multicentre studies have been conducted for severe malaria, visceral leishmaniasis, and cardiac Chagas disease, providing some novel important insights. Furthermore, studies of helminth infections have repeatedly shown the involvement of common loci in regulating susceptibility to distinct diseases such as schistosomiasis, ascariasis, trichuriasis, and onchocherciasis. As more studies are conducted, evidence is increasing that at least some of the identified susceptibility loci are shared not only among parasitic diseases but also with immunological disorders such as allergy or autoimmune disease, suggesting that parasites may have played a role in driving the evolution of the immune system. PMID:25273270

Mangano, V D; Modiano, D

2014-12-01

106

Deviance partitioning of host factors affecting parasitization in the European brown hare ( Lepus europaeus )  

Microsoft Academic Search

Deviance partitioning can provide new insights into the ecology of host-parasite interactions. We studied the host-related\\u000a factors influencing parasite prevalence, abundance, and species richness in European brown hares (Lepus europaeus) from northern Spain. We defined three groups of explanatory variables: host environment, host population, and individual\\u000a factors. We hypothesised that parasite infection rates and species richness were determined by different

Vanesa Alzaga; Paolo Tizzani; Pelayo Acevedo; Francisco Ruiz-Fons; Joaqun Vicente; Christian Gortzar

2009-01-01

107

GENETIC VARIATION IN A HOST-PARASITE ASSOCIATION: POTENTIAL FOR COEVOLUTION AND FREQUENCY-DEPENDENT SELECTION  

Microsoft Academic Search

Models of host-parasite coevolution assume the presence of genetic variation for host resistance and parasite infectivity, as well as genotype-specific interactions. We used the freshwater crustaceanDaphnia magnaand its bacterial microparasite Pasteuria ramosa to study genetic variation for host susceptibility and parasite infectivity within each of two populations. We sought to answer the following questions: Do host clones differ in their

Hans Joachim Carius; Tom J. Little; Dieter Ebert

2001-01-01

108

Host and parasite diversity jointly control disease risk in complex communities  

PubMed Central

Hostparasite interactions are embedded within complex communities composed of multiple host species and a cryptic assemblage of other parasites. To date, however, surprisingly few studies have explored the joint effects of host and parasite richness on disease risk, despite growing interest in the diversitydisease relationship. Here, we combined field surveys and mechanistic experiments to test how transmission of the virulent trematode Ribeiroia ondatrae was affected by the diversity of both amphibian hosts and coinfecting parasites. Within natural wetlands, host and parasite species richness correlated positively, consistent with theoretical predictions. Among sites that supported Ribeiroia, however, host and parasite richness interacted to negatively affect Ribeiroia transmission between its snail and amphibian hosts, particularly in species-poor assemblages. In laboratory and outdoor experiments designed to decouple the relative contributions of host and parasite diversity, increases in host richness decreased Ribeiroia infection by 1165%. Host richness also tended to decrease total infections by other parasite species (four of six instances), such that more diverse host assemblages exhibited ?40% fewer infections overall. Importantly, parasite richness further reduced both per capita and total Ribeiroia infection by 1520%, possibly owing to intrahost competition among coinfecting species. These findings provide evidence that parasitic and free-living diversity jointly regulate disease risk, help to resolve apparent contradictions in the diversitydisease relationship, and emphasize the challenges of integrating research on coinfection and host heterogeneity to develop a community ecology-based approach to infectious diseases. PMID:24082092

Johnson, Pieter T. J.; Preston, Daniel L.; Hoverman, Jason T.; LaFonte, Bryan E.

2013-01-01

109

Benefits of host genetic diversity for resistance to infection depend on parasite diversity  

PubMed Central

Host populations with high genetic diversity are predicted to have lower levels of infection prevalence. This theory assumes that host genetic diversity results in variation in susceptibility and that parasites exhibit variation in infectivity. Empirical studies on the effects of host heterogeneity typically neglect the role of parasite diversity. We conducted three laboratory experiments designed to test if genetic variation in Daphnia magna populations and genetic variation in its parasites together influence the course of parasite spread after introduction. We found that a natural D. magna population exhibited variation in susceptibility to infection by three parasite species and had strong host cloneparasite species interactions. There was no effect of host heterogeneity in experimental host populations (polycultures and monocultures) separately exposed to single strains of three parasite species. When we manipulated the genetic diversity of a single parasite species and exposed them to host monocultures and polycultures, we found that parasite prevalence increased with the number of parasite strains. Host monocultures exposed to several parasite strains had higher mean parasite prevalence and higher variance than polycultures. These results indicate that effect of host genetic diversity on the spread of infection depends on the level of genetic diversity in the parasite population. PMID:20503859

Ganz, Holly H.; Ebert, Dieter

2011-01-01

110

Complex Daphnia interactions with parasites and competitors.  

PubMed

Species interactions can strongly influence the size and dynamics of epidemics in populations of focal hosts. The "dilution effect" provides a particularly interesting type of interaction from a biological standpoint. Diluters - other host species which resist infection but remove environmentally-distributed propagules of parasites (spores) - should reduce disease prevalence in focal hosts. However, diluters and focal hosts may compete for shared resources. This combination of positive (dilution) and negative (competition) effects could greatly complicate, even undermine, the benefits of dilution and diluter species from the perspective of the focal host. Motivated by an example from the plankton (i.e., zooplankton hosts, a fungal parasite, and algal resources), we study a model of dilution and competition. Our model reveals a suite of five results: PMID:25445737

Cceres, C E; Davis, G; Duple, S; Hall, S R; Koss, A; Lee, P; Rapti, Z

2014-12-01

111

Gene expression differences underlying genotype-by-genotype specificity in a hostparasite system  

PubMed Central

In many systems, hostparasite evolutionary dynamics have led to the emergence and maintenance of diverse parasite and host genotypes within the same population. Genotypes vary in key attributes: Parasite genotypes vary in ability to infect, host genotypes vary in susceptibility, and infection outcome is frequently the result of both parties genotypic identities. These hostparasite genotype-by-genotype (GH GP) interactions influence evolutionary and ecological dynamics in important ways. Interactions can be produced through genetic variation; however, here, we assess the role of variable gene expression as an additional source of GH GP interactions. The bumblebee Bombus terrestris and its trypanosome gut parasite Crithidia bombi are a model system for hostparasite matching. Full-transcriptome sequencing of the bumblebee host revealed that different parasite genotypes indeed induce fundamentally different host expression responses and host genotypes vary in their responses to the infecting parasite genotype. It appears that broadly and successfully infecting parasite genotypes lead to reduced host immune gene expression relative to unexposed bees but induce the expression of genes responsible for controlling gene expression. Contrastingly, a poorly infecting parasite genotype induced the expression of immunologically important genes, including antimicrobial peptides. A targeted expression assay confirmed the transcriptome results and also revealed strong host genotype effects. In all, the expression of a number of genes depends on the host genotype and the parasite genotype and the interaction between both host and parasite genotypes. These results suggest that alongside sequence variation in coding immunological genes, variation that controls immune gene expression can also produce patterns of hostparasite specificity. PMID:24550506

Barribeau, Seth M.; Sadd, Ben M.; du Plessis, Louis; Schmid-Hempel, Paul

2014-01-01

112

Gene expression differences underlying genotype-by-genotype specificity in a host-parasite system.  

PubMed

In many systems, host-parasite evolutionary dynamics have led to the emergence and maintenance of diverse parasite and host genotypes within the same population. Genotypes vary in key attributes: Parasite genotypes vary in ability to infect, host genotypes vary in susceptibility, and infection outcome is frequently the result of both parties' genotypic identities. These host-parasite genotype-by-genotype (GH GP) interactions influence evolutionary and ecological dynamics in important ways. Interactions can be produced through genetic variation; however, here, we assess the role of variable gene expression as an additional source of GH GP interactions. The bumblebee Bombus terrestris and its trypanosome gut parasite Crithidia bombi are a model system for host-parasite matching. Full-transcriptome sequencing of the bumblebee host revealed that different parasite genotypes indeed induce fundamentally different host expression responses and host genotypes vary in their responses to the infecting parasite genotype. It appears that broadly and successfully infecting parasite genotypes lead to reduced host immune gene expression relative to unexposed bees but induce the expression of genes responsible for controlling gene expression. Contrastingly, a poorly infecting parasite genotype induced the expression of immunologically important genes, including antimicrobial peptides. A targeted expression assay confirmed the transcriptome results and also revealed strong host genotype effects. In all, the expression of a number of genes depends on the host genotype and the parasite genotype and the interaction between both host and parasite genotypes. These results suggest that alongside sequence variation in coding immunological genes, variation that controls immune gene expression can also produce patterns of host-parasite specificity. PMID:24550506

Barribeau, Seth M; Sadd, Ben M; du Plessis, Louis; Schmid-Hempel, Paul

2014-03-01

113

Maintenance of host variation in tolerance to pathogens and parasites  

E-print Network

Maintenance of host variation in tolerance to pathogens and parasites A. Besta,1 , A. Whiteb and resistance provide hosts with two distinct defense strategies against parasitism. In resistance the hosts ``fight'' the parasite directly, whereas in tolerance the hosts fight the disease by ameliorating

White, Andrew

114

Social learning of a brood parasite by its host.  

PubMed

Arms races between brood parasites and their hosts provide model systems for studying the evolutionary repercussions of species interactions. However, how naive hosts identify brood parasites as enemies remains poorly understood, despite its ecological and evolutionary significance. Here, we investigate whether young, cuckoo-naive superb fairy-wrens, Malurus cyaneus, can learn to recognize cuckoos as a threat through social transmission of information. Naive individuals were initially unresponsive to a cuckoo specimen, but after observing conspecifics mob a cuckoo, they made more whining and mobbing alarm calls, and spent more time physically mobbing the cuckoo. This is the first direct evidence that naive hosts can learn to identify brood parasites as enemies via social learning. PMID:23760171

Feeney, William E; Langmore, Naomi E

2013-08-23

115

Hymenolepis diminuta infections in tenebrionid beetles as a model system for ecological interactions between helminth parasites and terrestrial intermediate hosts: a review and meta-analysis.  

PubMed

The cestode Hymenolepis diminuta (Cyclophyllidea) uses a variety of insects as its intermediate host, where ingestion of eggs results in development in the hemocoel of a cysticercoid that is infective to a rat definitive host. Species in 2 genera, Tenebrio and Tribolium (Coleoptera: Tenebrionidae) have been used extensively as laboratory intermediate hosts. This review examines experimental studies on ecological aspects of the relationship between H. diminuta and tenebrionid beetles, including the acquisition and establishment of the parasite, host effects on the parasite, and parasite effects on the host. A meta-analysis of infection results from the literature revealed strong relationships across host species and strains between (1) prevalence and intensity of infection, (2) efficiency of cysticercoid production and exposure conditions, and (3) variance in abundance or intensity of infection relative to their respective means. The underlying mechanisms producing these patterns remain elusive. Comparative studies are infrequent, and the use of divergent methodologies hampers comparisons among studies. In spite of these problems, there is much to recommend this as a terrestrial host-parasite model system. It represents those relationships in which mostly minor, but occasionally major, responses to parasitic infection occur, and in which host genetics and environmental conditions can serve as modifying factors. Moreover, this is a tractable experimental system, and is backed by an extensive literature on host biology. PMID:23952690

Shostak, Allen W

2014-02-01

116

The evolutionary dynamics of variant antigen genes in Babesia reveal a history of genomic innovation underlying hostparasite interaction  

PubMed Central

Babesia spp. are tick-borne, intraerythrocytic hemoparasites that use antigenic variation to resist host immunity, through sequential modification of the parasite-derived variant erythrocyte surface antigen (VESA) expressed on the infected red blood cell surface. We identified the genomic processes driving antigenic diversity in genes encoding VESA (ves1) through comparative analysis within and between three Babesia species, (B. bigemina, B. divergens and B. bovis). Ves1 structure diverges rapidly after speciation, notably through the evolution of shortened forms (ves2) from 5? ends of canonical ves1 genes. Phylogenetic analyses show that ves1 genes are transposed between loci routinely, whereas ves2 genes are not. Similarly, analysis of sequence mosaicism shows that recombination drives variation in ves1 sequences, but less so for ves2, indicating the adoption of different mechanisms for variation of the two families. Proteomic analysis of the B. bigemina PR isolate shows that two dominant VESA1 proteins are expressed in the population, whereas numerous VESA2 proteins are co-expressed, consistent with differential transcriptional regulation of each family. Hence, VESA2 proteins are abundant and previously unrecognized elements of Babesia biology, with evolutionary dynamics consistently different to those of VESA1, suggesting that their functions are distinct. PMID:24799432

Jackson, Andrew P.; Otto, Thomas D.; Darby, Alistair; Ramaprasad, Abhinay; Xia, Dong; Echaide, Ignacio Eduardo; Farber, Marisa; Gahlot, Sunayna; Gamble, John; Gupta, Dinesh; Gupta, Yask; Jackson, Louise; Malandrin, Laurence; Malas, Tareq B.; Moussa, Ehab; Nair, Mridul; Reid, Adam J.; Sanders, Mandy; Sharma, Jyotsna; Tracey, Alan; Quail, Mike A.; Weir, William; Wastling, Jonathan M.; Hall, Neil; Willadsen, Peter; Lingelbach, Klaus; Shiels, Brian; Tait, Andy; Berriman, Matt; Allred, David R.; Pain, Arnab

2014-01-01

117

The evolutionary dynamics of variant antigen genes in Babesia reveal a history of genomic innovation underlying host-parasite interaction.  

PubMed

Babesia spp. are tick-borne, intraerythrocytic hemoparasites that use antigenic variation to resist host immunity, through sequential modification of the parasite-derived variant erythrocyte surface antigen (VESA) expressed on the infected red blood cell surface. We identified the genomic processes driving antigenic diversity in genes encoding VESA (ves1) through comparative analysis within and between three Babesia species, (B. bigemina, B. divergens and B. bovis). Ves1 structure diverges rapidly after speciation, notably through the evolution of shortened forms (ves2) from 5' ends of canonical ves1 genes. Phylogenetic analyses show that ves1 genes are transposed between loci routinely, whereas ves2 genes are not. Similarly, analysis of sequence mosaicism shows that recombination drives variation in ves1 sequences, but less so for ves2, indicating the adoption of different mechanisms for variation of the two families. Proteomic analysis of the B. bigemina PR isolate shows that two dominant VESA1 proteins are expressed in the population, whereas numerous VESA2 proteins are co-expressed, consistent with differential transcriptional regulation of each family. Hence, VESA2 proteins are abundant and previously unrecognized elements of Babesia biology, with evolutionary dynamics consistently different to those of VESA1, suggesting that their functions are distinct. PMID:24799432

Jackson, Andrew P; Otto, Thomas D; Darby, Alistair; Ramaprasad, Abhinay; Xia, Dong; Echaide, Ignacio Eduardo; Farber, Marisa; Gahlot, Sunayna; Gamble, John; Gupta, Dinesh; Gupta, Yask; Jackson, Louise; Malandrin, Laurence; Malas, Tareq B; Moussa, Ehab; Nair, Mridul; Reid, Adam J; Sanders, Mandy; Sharma, Jyotsna; Tracey, Alan; Quail, Mike A; Weir, William; Wastling, Jonathan M; Hall, Neil; Willadsen, Peter; Lingelbach, Klaus; Shiels, Brian; Tait, Andy; Berriman, Matt; Allred, David R; Pain, Arnab

2014-06-01

118

The potential for arms race and Red Queen coevolution in a protist hostparasite system  

PubMed Central

The dynamics and consequences of hostparasite coevolution depend on the nature of host genotype-by-parasite genotype interactions (G G) for host and parasite fitness. G G with crossing reaction norms can yield cyclic dynamics of allele frequencies (Red Queen dynamics) while G G where the variance among host genotypes differs between parasite genotypes results in selective sweeps (arms race dynamics). Here, we investigate the relative potential for arms race and Red Queen coevolution in a protist hostparasite system, the dinoflagellate Alexandrium minutum and its parasite Parvilucifera sinerae. We challenged nine different clones of A. minutum with 10 clones of P. sinerae in a fully factorial design and measured infection success and host and parasite fitness. Each host genotype was successfully infected by four to ten of the parasite genotypes. There were strong G Gs for infection success, as well as both host and parasite fitness. About three quarters of the G G variance components for host and parasite fitness were due to crossing reaction norms. There were no general costs of resistance or infectivity. We conclude that there is high potential for Red Queen dynamics in this hostparasite system.

Rberg, Lars; Alacid, Elisabet; Garces, Esther; Figueroa, Rosa

2014-01-01

119

The potential for arms race and Red Queen coevolution in a protist host-parasite system.  

PubMed

The dynamics and consequences of host-parasite coevolution depend on the nature of host genotype-by-parasite genotype interactions (G G) for host and parasite fitness. G G with crossing reaction norms can yield cyclic dynamics of allele frequencies ("Red Queen" dynamics) while G G where the variance among host genotypes differs between parasite genotypes results in selective sweeps ("arms race" dynamics). Here, we investigate the relative potential for arms race and Red Queen coevolution in a protist host-parasite system, the dinoflagellate Alexandrium minutum and its parasite Parvilucifera sinerae. We challenged nine different clones of A. minutum with 10 clones of P. sinerae in a fully factorial design and measured infection success and host and parasite fitness. Each host genotype was successfully infected by four to ten of the parasite genotypes. There were strong G Gs for infection success, as well as both host and parasite fitness. About three quarters of the G G variance components for host and parasite fitness were due to crossing reaction norms. There were no general costs of resistance or infectivity. We conclude that there is high potential for Red Queen dynamics in this host-parasite system. PMID:25558368

Rberg, Lars; Alacid, Elisabet; Garces, Esther; Figueroa, Rosa

2014-12-01

120

Immune response to sympatric and allopatric parasites in a snail-trematode interaction  

PubMed Central

Background The outcome of parasite exposure depends on the (1) genetic specificity of the interaction, (2) induction of host defenses, and (3) parasite counter defenses. We studied both the genetic specificity for infection and the specificity for the host-defense response in a snail-trematode interaction (Potamopyrgus antipodarum-Microphallus sp.) by conducting a reciprocal cross-infection experiment between two populations of host and parasite. Results We found that infection was greater in sympatric host-parasite combinations. We also found that the host-defense response (hemocyte concentration) was induced by parasite exposure, but the response did not increase with increased parasite dose nor did it depend on parasite source, host source, or host-parasite combination. Conclusion The results are consistent with a genetically specific host-parasite interaction, but inconsistent with a general arms-race type interaction where allocation to defense is the main determinant of host resistance. PMID:15927050

Osnas, Erik E; Lively, Curtis M

2005-01-01

121

The interaction of the novel 30C02 cyst nematode effector protein with a plant ?-1,3-endoglucanase may suppress host defence to promote parasitism.  

PubMed

Phytoparasitic nematodes secrete an array of effector proteins to modify selected recipient plant cells into elaborate and essential feeding sites. The biological function of the novel 30C02 effector protein of the soybean cyst nematode, Heterodera glycines, was studied using Arabidopsis thaliana as host and the beet cyst nematode, Heterodera schachtii, which contains a homologue of the 30C02 gene. Expression of Hg30C02 in Arabidopsis did not affect plant growth and development but increased plant susceptibility to infection by H. schachtii. The 30C02 protein interacted with a specific (AT4G16260) host plant ?-1,3-endoglucanase in both yeast and plant cells, possibly to interfere with its role as a plant pathogenesis-related protein. Interestingly, the peak expression of 30C02 in the nematode and peak expression of At4g16260 in plant roots coincided at around 3-5 d after root infection by the nematode, after which the relative expression of At4g16260 declined significantly. An Arabidopsis At4g16260 T-DNA mutant showed increased susceptibility to cyst nematode infection, and plants that overexpressed At4g16260 were reduced in nematode susceptibility, suggesting a potential role of host ?-1,3-endoglucanase in the defence response against H. schachtii infection. Arabidopsis plants that expressed dsRNA and its processed small interfering RNA complementary to the Hg30C02 sequence were not phenotypically different from non-transformed plants, but they exhibited a strong RNA interference-mediated resistance to infection by H. schachtii. The collective results suggest that, as with other pathogens, active suppression of host defence is a critical component for successful parasitism by nematodes and a vulnerable target to disrupt the parasitic cycle. PMID:22442414

Hamamouch, Noureddine; Li, Chunying; Hewezi, Tarek; Baum, Thomas J; Mitchum, Melissa G; Hussey, Richard S; Vodkin, Lila O; Davis, Eric L

2012-06-01

122

Modelling Parasite Transmission in a Grazing System: The Importance of Host Behaviour and Immunity  

PubMed Central

Parasitic helminths present one of the most pervasive challenges to grazing herbivores. Many macro-parasite transmission models focus on host physiological defence strategies, omitting more complex interactions between hosts and their environments. This work represents the first model that integrates both the behavioural and physiological elements of gastro-intestinal nematode transmission dynamics in a managed grazing system. A spatially explicit, individual-based, stochastic model is developed, that incorporates both the hosts immunological responses to parasitism, and key grazing behaviours including faecal avoidance. The results demonstrate that grazing behaviour affects both the timing and intensity of parasite outbreaks, through generating spatial heterogeneity in parasite risk and nutritional resources, and changing the timing of exposure to the parasites free-living stages. The influence of grazing behaviour varies with the host-parasite combination, dependent on the development times of different parasite species and variations in host immune response. Our outputs include the counterintuitive finding that under certain conditions perceived parasite avoidance behaviours (faecal avoidance) can increase parasite risk, for certain host-parasite combinations. Through incorporating the two-way interaction between infection dynamics and grazing behaviour, the potential benefits of parasite-induced anorexia are also demonstrated. Hosts with phenotypic plasticity in grazing behaviour, that make grazing decisions dependent on current parasite burden, can reduce infection with minimal loss of intake over the grazing season. This paper explores how both host behaviours and immunity influence macro-parasite transmission in a spatially and temporally heterogeneous environment. The magnitude and timing of parasite outbreaks is influenced by host immunity and behaviour, and the interactions between them; the incorporation of both regulatory processes is required to fully understand transmission dynamics. Understanding of both physiological and behavioural defence strategies will aid the development of novel approaches for control. PMID:24223133

Fox, Naomi J.; Marion, Glenn; Davidson, Ross S.; White, Piran C. L.; Hutchings, Michael R.

2013-01-01

123

Rapid evolution of antimicrobial peptide genes in an insect host-social parasite system.  

PubMed

Selection, as a major driver for evolution in host-parasite interactions, may act on two levels; the virulence of the pathogen, and the hosts' defence system. Effectors of the host defence system might evolve faster than other genes e.g. those involved in adaptation to changes in life history or environmental fluctuations. Host-parasite interactions at the level of hosts and their specific social parasites, present a special setting for evolutionarily driven selection, as both share the same environmental conditions and pathogen pressures. Here, we study the evolution of antimicrobial peptide (AMP) genes, in six host bumblebee and their socially parasitic cuckoo bumblebee species. The selected AMP genes evolved much faster than non-immune genes, but only defensin-1 showed significant differences between host and social parasite. Nucleotide diversity and codon-by-codon analyses confirmed that purifying selection is the main selective force acting on bumblebee defence genes. PMID:24530902

Erler, Silvio; Lhomme, Patrick; Rasmont, Pierre; Lattorff, H Michael G

2014-04-01

124

The evolution of parasite manipulation of host dispersal  

E-print Network

The evolution of parasite manipulation of host dispersal Se´bastien Lion1,*, Minus van Baalen1 of host dispersal behaviour by parasites using spatially explicit individual-based simulations. We find that when dispersal is local, parasites always gain from increasing their hosts' dispersal rate, although

Lion, Sébastien

125

Genetic architecture of resistance in Daphnia hosts against two species of host-specific parasites.  

PubMed

Understanding the genetic architecture of host resistance is key for understanding the evolution of host-parasite interactions. Evolutionary models often assume simple genetics based on few loci and strong epistasis. It is unknown, however, whether these assumptions apply to natural populations. Using a quantitative trait loci (QTL) approach, we explore the genetic architecture of resistance in the crustacean Daphnia magna to two of its natural parasites: the horizontally transmitted bacterium Pasteuria ramosa and the horizontally and vertically transmitted microsporidium Hamiltosporidium tvaerminnensis. These two systems have become models for studies on the evolution of host-parasite interactions. In the QTL panel used here, Daphnia's resistance to P. ramosa is controlled by a single major QTL (which explains 50% of the observed variation). Resistance to H. tvaerminnensis horizontal infections shows a signature of a quantitative trait based in multiple loci with weak epistatic interactions (together explaining 38% variation). Resistance to H. tvaerminnensis vertical infections, however, shows only one QTL (explaining 13.5% variance) that colocalizes with one of the QTLs for horizontal infections. QTLs for resistance to Pasteuria and Hamiltosporidium do not colocalize. We conclude that the genetics of resistance in D. magna are drastically different for these two parasites. Furthermore, we infer that based on these and earlier results, the mechanisms of coevolution differ strongly for the two host-parasite systems. Only the Pasteuria-Daphnia system is expected to follow the negative frequency-dependent selection (Red Queen) model. How coevolution works in the Hamiltosporidium-Daphnia system remains unclear. PMID:25335558

Routtu, J; Ebert, D

2015-02-01

126

Larval size in acanthocephalan parasites: Influence of intraspecific competition and effects on intermediate host behavioural changes  

PubMed Central

Background Parasites often face a trade-off between exploitation of host resources and transmission probabilities to the next host. In helminths, larval growth, a major component of adult parasite fitness, is linked to exploitation of intermediate host resources and is influenced by the presence of co-infecting conspecifics. In manipulative parasites, larval growth strategy could also interact with their ability to alter intermediate host phenotype and influence parasite transmission. Methods We used experimental infections of Gammarus pulex by Pomphorhynchus laevis (Acanthocephala), to investigate larval size effects on host behavioural manipulation among different parasite sibships and various degrees of intra-host competition. Results Intra-host competition reduced mean P. laevis cystacanth size, but the largest cystacanth within a host always reached the same size. Therefore, all co-infecting parasites did not equally suffer from intraspecific competition. Under no intra-host competition (1 parasite per host), larval size was positively correlated with host phototaxis. At higher infection intensities, this relationship disappeared, possibly because of strong competition for host resources, and thus larval growth, and limited manipulative abilities of co-infecting larval acanthocephalans. Conclusions Our study indicates that behavioural manipulation is a condition-dependant phenomenon that needs the integration of parasite-related variables to be fully understood. PMID:22876882

2012-01-01

127

Host density drives the postglacial migration of the tree parasite, Epifagus virginiana  

PubMed Central

To survive changes in climate, successful species shift their geographic ranges to remain in suitable habitats. For parasites and other highly specialized species, distributional changes not only are dictated by climate but can also be engineered by their hosts. The extent of host control on parasite range expansion is revealed through comparisons of host and parasite migration and demographic histories. However, understanding the codistributional history of entire forest communities is complicated by challenges in synthesizing datasets from multiple interacting species of differing datatypes. Here we integrate genetic and fossil pollen datasets from a hostparasite pair; specifically, the population structure of the parasitic plant (Epifagus virginiana) was compared with both its host (Fagus grandifolia) genetic patterns and abundance data from the paleopollen record of the last 21,000 y. Through tests of phylogeographic structure and spatial linear regression models we find, surprisingly, host range changes had little effect on the parasite's range expansion and instead host density is the main driver of parasite spread. Unlike other symbionts that have been used as proxies to track their host's movements, this parasite's migration routes are incongruent with the host and instead reflect the greater importance of host density in this community's assembly. Furthermore, these results confirm predictions of disease ecological models regarding the role of host density in the spread of pathogens. Due to host density constraints, highly specialized species may have low migration capacities and long lag times before colonization of new areas. PMID:20841421

Tsai, Yi-Hsin Erica; Manos, Paul S.

2010-01-01

128

Volatile Chemical Cues Guide Host Location and Host Selection by Parasitic Plants  

Microsoft Academic Search

The importance of plant volatiles in mediating interactions between plant species is much debated. Here, we demonstrate that the parasitic plant Cuscuta pentagona (dodder) uses volatile cues for host location. Cuscuta pentagona seedlings exhibit directed growth toward nearby tomato plants (Lycopersicon esculentum) and toward extracted tomato-plant volatiles presented in the absence of other cues. Impatiens (Impatiens wallerana) and wheat plants

Justin B. Runyon; Mark C. Mescher; Consuelo M. De Moraes

2006-01-01

129

Brood parasitic cowbird nestlings use host young to procure resources.  

PubMed

Young brood parasites that tolerate the company of host offspring challenge the existing evolutionary view of family life. In theory, all parasitic nestlings should be ruthlessly self-interested and should kill host offspring soon after hatching. Yet many species allow host young to live, even though they are rivals for host resources. Here we show that the tolerance of host nestlings by the parasitic brown-headed cowbird Molothrus ater is adaptive. Host young procure the cowbird a higher provisioning rate, so it grows more rapidly. The cowbird's unexpected altruism toward host offspring simply promotes its selfish interests in exploiting host parents. PMID:15297677

Kilner, Rebecca M; Madden, Joah R; Hauber, Mark E

2004-08-01

130

Why do parasitized hosts look different? Resolving the "chicken-egg" dilemma.  

PubMed

Phenotypic differences between infected and non-infected hosts are often assumed to be the consequence of parasite infection. However, pre-existing differences in hosts' phenotypes may promote differential susceptibility to infection. The phenotypic variability observed within the host population may therefore be a cause rather than a consequence of infection. In this study, we aimed at disentangling the causes and the consequences of parasite infection by calculating the value of a phenotypic trait (i.e., the growth rate) of the hosts both before and after infection occurred. That procedure was applied to two natural systems of host-parasite interactions. In the first system, the infection level of an ectoparasite (Tracheliastes polycolpus) decreases the growth rate of its fish host (the rostrum dace, Leuciscus leuciscus). Reciprocally, this same phenotypic trait before infection modulated the future level of host sensitivity to the direct pathogenic effect of the parasite, namely the level of fin degradation. In the second model, causes and consequences linked the growth rate of the fish host (the rainbow smelt, Osmerus mordax) and the level of endoparasite infection (Proteocephalus tetrastomus). Indeed, the host's growth rate before infection determined the number of parasites later in life, and the parasite biovolume then decreased the host's growth rate of heavily infected hosts. We demonstrated that reciprocal effects between host phenotypes and parasite infection can occur simultaneously in the wild, and that the observed variation in the host phenotype population was not necessarily a consequence of parasite infection. Disentangling the causality of host-parasite interactions should contribute substantially to evaluating the role of parasites in ecological and evolutionary processes. PMID:19189131

Blanchet, Simon; Mjean, Lionel; Bourque, Jean-Franois; Lek, Sovan; Thomas, Frdric; Marcogliese, David J; Dodson, Julian J; Loot, Graldine

2009-05-01

131

Exploring the molecular landscape of host-parasite coevolution.  

PubMed

Host-parasite coevolution is a dynamic process that can be studied at the phenotypic, genetic, and molecular levels. Although much of what we currently know about coevolution has been learned through phenotypic measures, recent advances in molecular techniques have provided tools to greatly deepen this research. Both the availability of full-genome sequences and the increasing feasibility of high-throughput gene expression profiling are leading to the discovery of genes that have a key role in antagonistic interactions between naturally coevolving species. Identification of such genes can enable direct observation, rather than inference, of the host-parasite coevolutionary dynamic. The Daphnia magna-Pasteuria ramosa host-parasite model is a prime example of an interaction that has been well studied at the population and whole-organism levels, and much is known about genotype- and environment-specific interactions from a phenotypic perspective. Now, with the recent completion of genome sequences for two Daphnia species, and a transcriptomics project under way, coevolution between these two enemies is being investigated directly at the level of interacting genes. PMID:19843595

Allen, D E; Little, T J

2009-01-01

132

Original article Host sex and parasite genetic diversity  

E-print Network

Original article Host sex and parasite genetic diversity Damien Caillaud a,c,1 , Franck Prugnolle a 21 June 2006 Available online 10 July 2006 Abstract Is the genetic diversity of parasites infecting). Using seven microsatellite markers, we demonstrate that parasites from male hosts are genetically more

133

Intestinal parasitic infections in hosted Saharawi children.  

PubMed

Literatures on intestinal parasitic infections in Saharawi children were scarce and distributed in non parasitological journals. This was the first article that specifically highlighted on the prevalence of these infections in 270 Saharawi children aged from 6 to 12 years hosted in Spain. Six different intestinal parasites were identified in this study and 78, 46, 40, 24, 13 and 5 were positive for Giardia lamblia (29%), Entamoeba coli (17%), Blastocystis hominis (15%), Endolimax nana (9%), Hymenolepis nana (5%) and Enterobius vermicularis (2%), respectively. Mixed intestinal parasitic infections were seen in 12 (4.4%) studied children. Six (2.2%) double infections for G. lamblia and B. hominis were seen in these children while in four (1.5%) had G. lamblia and H. nana. Triple intestinal parasitic infections of G. lamblia, B. hominis and H. nana were observed in two (0.7%) of the children studied. In the other hand, about 14.8% of the studied children had a mild anaemia and 15.5 and 16.6% had iron deficiency and eosinophilia, respectively. PMID:22433884

Soriano, J M; Domnech, G; Martnez, M C; Maes, J; Soriano, F

2011-12-01

134

Original article Genetic variability of host-parasite relationship  

E-print Network

Original article Genetic variability of host-parasite relationship traits: utilization of isofemale lines in a Drosophila simulans parasitic wasp Y. Carton P. Capy A.J. Nappi 1Centre National de la in the successful parasitization of larvae of Drosophila melanogaster and D. simulans by the hymenopteran parasite

Paris-Sud XI, Université de

135

Constraints on host use by a parasitic plant.  

PubMed

Consumers do not always utilize all suitable hosts. Understanding why parasitic plants do not always parasitize potentially suitable hosts requires a better understanding of the constraints that limit host use by parasitic plants. In Texas salt marshes, the parasitic plant Cuscuta indecora rarely parasitizes three hosts that support vigorous growth in the greenhouse. We identified three constraints on host use by C. indecora. First, a mismatch between the phenology of C. indecora and some suitable hosts meant that these hosts were not abundant when C. indecora was growing most vigorously, and therefore were underutilized. Second, C. indecora preferentially parasitized tall plants versus short ones, causing relatively short species to be underutilized. Third, C. indecora overwinters in some perennial hosts but has to reinfect annual hosts each year, causing annuals and perennials that do not support overwintering to be underutilized. In combination, these constraints, which reflect the general lack of mobility of parasitic plants relative to herbivores, remove half of the potential host species from the actual diet of C. indecora, and therefore likely represent a major limitation on the success of this parasite. Similar constraints are likely to limit the realized host range of many parasitic plants and select for generalized diet preferences. PMID:20490550

Marquardt, Emily S; Pennings, Steven C

2010-09-01

136

The interplay between host toxins and parasitism by Amoebophrya  

Microsoft Academic Search

The parasitic dinoflagellate Amoebophrya sp. ex Karlodinium veneficum was used to test two hypotheses: (1) infection of cells decreases with increasing host toxicity and (2) parasitism causes the catabolism of host toxin. To test the first hypothesis, host strains differing in toxin content were inoculated with dinospores of Amoebophrya sp. derived from infected cultures of toxic and non-toxic K. veneficum,

Xuemei Bai; Jason E. Adolf; Tsvetan Bachvaroff; D. Wayne Coats

2007-01-01

137

Does chemical aposematic (warning) signaling occur between host plants and their potential parasitic plants?  

PubMed Central

Aposematism (warning) signaling is a common defensive mechanism toward predatory or herbivorous animals, i.e., interactions between different trophic levels. I propose that it should be considered at least as a working hypothesis that chemical aposematism operates between certain host plants and their plant predators, parasitic plants, and that although they are also plants, they belong to a higher trophic level. Specific host plant genotypes emit known repelling chemical signals toward parasitic plants, which reduce the level of, slow the directional parasite growth (attack) toward the signaling hosts, or even cause parasitic plants to grow away from them in response to these chemicals. Chemical host aposematism toward parasitic plants may be a common but overlooked defense from parasitic plants. PMID:23656862

Lev-Yadun, Simcha

2013-01-01

138

Brood parasitism causes female-biased host nestling mortality regardless of parasite species  

E-print Network

Brood parasitism causes female-biased host nestling mortality regardless of parasite species ROBERT Molothrus ater brood parasitism of Song Sparrows Melospiza melodia results in a 50% reduction is as signifi- cant as nest predation in affecting demography. Many avian brood parasites possess special

Zanette, Liana

139

On Genetic Specificity in Symbiont-Mediated Host-Parasite Coevolution  

PubMed Central

Existing theory of host-parasite interactions has identified the genetic specificity of interaction as a key variable affecting the outcome of coevolution. The Matching Alleles (MA) and Gene For Gene (GFG) models have been extensively studied as the canonical examples of specific and non-specific interaction. The generality of these models has recently been challenged by uncovering real-world host-parasite systems exhibiting specificity patterns that fit neither MA nor GFG, and by the discovery of symbiotic bacteria protecting insect hosts against parasites. In the present paper we address both challenges, simulating a large number of non-canonical models of host-parasite interactions that explicitly incorporate symbiont-based host resistance. To assess the genetic specialisation in these hybrid models, we develop a quantitative index of specificity applicable to any coevolutionary model based on a fitness matrix. We find qualitative and quantitative effects of host-parasite and symbiont-parasite specificities on genotype frequency dynamics, allele survival, and mean host and parasite fitnesses. PMID:22956894

Kwiatkowski, Marek; Engelstdter, Jan; Vorburger, Christoph

2012-01-01

140

Review on Trypanosoma cruzi: Host Cell Interaction.  

PubMed

Trypanosoma cruzi, the causative agent of Chagas' disease, which affects a large number of individuals in Central and South America, is transmitted to vertebrate hosts by blood-sucking insects. This protozoan is an obligate intracellular parasite. The infective forms of the parasite are metacyclic and bloodstream trypomastigote and amastigote. Metacyclic trypomastigotes are released with the feces of the insect while amastigotes and bloodstream trypomastigotes are released from the infected host cells of the vertebrate host after a complex intracellular life cycle. The recognition between parasite and mammalian host cell involves numerous molecules present in both cell types. Here, we present a brief review of the interaction between Trypanosoma cruzi and its host cells, mainly emphasizing the mechanisms and molecules that participate in the T. cruzi invasion process of the mammalian cells. PMID:20811486

de Souza, Wanderley; de Carvalho, Tecia Maria Ulisses; Barrias, Emile Santos

2010-01-01

141

Interaction between Parasitophorous Vacuolar Membrane-associated GRA3 and Calcium Modulating Ligand of Host Cell Endoplasmic Reticulum in the Parasitism of Toxoplasma gondii  

PubMed Central

A monoclonal antibody against Toxoplasma gondii of Tg556 clone (Tg556) blotted a 29 kDa protein, which was localized in the dense granules of tachyzoites and secreted into the parasitophorous vacuolar membrane (PVM) after infection to host cells. A cDNA fragment encoding the protein was obtained by screening a T. gondii cDNA expression library with Tg556, and the full-length was completed by 5'-RACE of 2,086 bp containing an open reading frame (ORF) of 669 bp. The ORF encoded a polypeptide of 222 amino acids homologous to the revised GRA3 but not to the first reported one. The polypeptide has 3 hydrophobic moieties of an N-terminal stop transfer sequence and 2 transmembrane domains (TMD) in posterior half of the sequence, a cytoplasmic localization motif after the second TMD and an endoplasmic reticulum (ER) retrival motif in the C-terminal end, which suggests GRA3 as a type III transmembrane protein. With the ORF of GRA3, yeast two-hybrid assay was performed in HeLa cDNA expression library, which resulted in the interaction of GRA3 with calcium modulating ligand (CAMLG), a type II transmembrane protein of ER. The specific binding of GRA3 and CAMLG was confirmed by glutathione S-transferase (GST) pull-down and immunoprecipitation assays. The localities of fluorescence transfectionally expressed from GRA3 and CAMLG plasmids were overlapped completely in HeLa cell cytoplasm. In immunofluorescence assay, GRA3 and CAMLG were shown to be co-localized in the PVM of host cells. Structural binding of PVM-inserted GRA3 to CAMLG of ER suggested the receptor-ligand of ER recruitment to PVM during the parasitism of T. gondii. PMID:19127325

Kim, Ji Yeon; Ahn, Hye-Jin; Ryu, Kyung Ju

2008-01-01

142

Host nutrition alters the variance in parasite transmission potential.  

PubMed

The environmental conditions experienced by hosts are known to affect their mean parasite transmission potential. How different conditions may affect the variance of transmission potential has received less attention, but is an important question for disease management, especially if specific ecological contexts are more likely to foster a few extremely infectious hosts. Using the obligate-killing bacterium Pasteuria ramosa and its crustacean host Daphnia magna, we analysed how host nutrition affected the variance of individual parasite loads, and, therefore, transmission potential. Under low food, individual parasite loads showed similar mean and variance, following a Poisson distribution. By contrast, among well-nourished hosts, parasite loads were right-skewed and overdispersed, following a negative binomial distribution. Abundant food may, therefore, yield individuals causing potentially more transmission than the population average. Measuring both the mean and variance of individual parasite loads in controlled experimental infections may offer a useful way of revealing risk factors for potential highly infectious hosts. PMID:23407498

Vale, Pedro F; Choisy, Marc; Little, Tom J

2013-04-23

143

Host nutrition alters the variance in parasite transmission potential  

PubMed Central

The environmental conditions experienced by hosts are known to affect their mean parasite transmission potential. How different conditions may affect the variance of transmission potential has received less attention, but is an important question for disease management, especially if specific ecological contexts are more likely to foster a few extremely infectious hosts. Using the obligate-killing bacterium Pasteuria ramosa and its crustacean host Daphnia magna, we analysed how host nutrition affected the variance of individual parasite loads, and, therefore, transmission potential. Under low food, individual parasite loads showed similar mean and variance, following a Poisson distribution. By contrast, among well-nourished hosts, parasite loads were right-skewed and overdispersed, following a negative binomial distribution. Abundant food may, therefore, yield individuals causing potentially more transmission than the population average. Measuring both the mean and variance of individual parasite loads in controlled experimental infections may offer a useful way of revealing risk factors for potential highly infectious hosts. PMID:23407498

Vale, Pedro F.; Choisy, Marc; Little, Tom J.

2013-01-01

144

Interactions among co-infecting parasite species: a mechanism maintaining genetic variation in parasites?  

PubMed Central

Individuals of free-living organisms are often infected simultaneously by a community of parasites. If the co-infecting parasites interact, then this can add significantly to the diversity of host genotypeparasite genotype interactions. However, interactions between parasite species are usually not examined considering potential variation in interactions between different strain combinations of co-infecting parasites. Here, we examined the importance of interactions between strains of fish eye flukes Diplostomum spathaceum and Diplostomum gasterostei on their infectivity in naive fish hosts. We assessed the infection success of strains of both species in single-strain exposures and in co-exposures with a random strain of the other species. Parasite infection success did not consistently increase or decrease in the co-exposure treatment, but depended on the combinations of co-infecting parasite strains. This disrupted the relative infectivity of D. spathaceum strains observed in single-strain exposures. The infection success of D. gasterostei strains was independent of exposure type. These results suggest that interactions among parasite species may be strain specific and potentially promote maintenance of genetic polymorphism in parasite populations. PMID:18957364

Seppl, Otto; Karvonen, Anssi; Tellervo Valtonen, E.; Jokela, Jukka

2008-01-01

145

Homage to Linnaeus: How many parasites? How many hosts?  

E-print Network

Homage to Linnaeus: How many parasites? How many hosts? Andy Dobson* , Kevin D. Lafferty , Armand M emphasis has been placed on counts of free-living species than on parasitic species. We rectify this by quantifying the numbers and proportion of parasitic species. We estimate that there are between 75,000 and 300

Utrecht, Universiteit

146

Intraspecific brood parasitism in the moorhen: parentage and parasite-host relationships determined by DNA fingerprinting  

Microsoft Academic Search

Parasitic female moorhens (Gallinula chloropus) lay from one to six eggs in the nests of conspecific neighbours. DNA fingerprinting was used to show that parasitic eggs\\u000a could be correctly identified when they appeared in addition to or outside the hosts laying sequence. Moorhen hosts accept\\u000a all parasitic eggs laid after the 2nd day of their laying period. To understand why

Susan B. McRae; Terry Burke

1996-01-01

147

[Apoptosis and programmed cell death. Host parasite relationship new paradigm].  

PubMed

Apoptosis and programmed cell death are amongst the most fascinating new concepts for understanding the host-parasite relationship. A growing body data is raising questions about the impact of the death of an individual parasite on the survival of the parasite population as a whole. Does the parasite induce the death of the host cell as an expression of virulence or does it inhibit that death as a factor for transmissibility? Current evidence that these effects are mediated through specific highly regulated mechanisms suggest that deciphering programmed cell death could provide new tools for control of parasitic diseases. PMID:16775931

Picot, S

2006-04-01

148

Host stadium specificity in the gregarine assemblage parasitizing Tenebrio molitor.  

PubMed

Reciprocal cross-stadia experimental infections were used to demonstrate stadium specificity within the gregarine assemblage parasitizing Tenebrio molitor, the yellow mealworm. Gregarina cuneata, Gregarina polymorpha, and Gregarina steini are characteristic parasites of larval T. molitor. Gregarina niphandrodes is a characteristic parasite of adult T. molitor. Experimental infections were produced in all homologous host-parasite combinations. No infection was produced in heterologous or cross-stadia combinations. This study introduces the concept of separate, distinct parasite niches corresponding to separate life cycle stages and established by known, predictable life cycle events within a single host species. PMID:1556647

Clopton, R E; Janovy, J; Percival, T J

1992-04-01

149

Anthelmintic treatment alters the parasite community in a wild mouse host  

PubMed Central

Individuals are often co-infected with several parasite species, yet the consequences of drug treatment on the dynamics of parasite communities in wild populations have rarely been measured. Here, we experimentally reduced nematode infection in a wild mouse population and measured the effects on other non-target parasites. A single oral dose of the anthelmintic, ivermectin, significantly reduced nematode infection, but resulted in a reciprocal increase in other gastrointestinal parasites, specifically coccidial protozoans and cestodes. These results highlight the possibility that drug therapy may have unintended consequences for non-target parasites and that hostparasite dynamics cannot always be fully understood in the framework of single hostparasite interactions. PMID:23658004

Pedersen, Amy B.; Antonovics, Janis

2013-01-01

150

Anthelmintic treatment alters the parasite community in a wild mouse host.  

PubMed

Individuals are often co-infected with several parasite species, yet the consequences of drug treatment on the dynamics of parasite communities in wild populations have rarely been measured. Here, we experimentally reduced nematode infection in a wild mouse population and measured the effects on other non-target parasites. A single oral dose of the anthelmintic, ivermectin, significantly reduced nematode infection, but resulted in a reciprocal increase in other gastrointestinal parasites, specifically coccidial protozoans and cestodes. These results highlight the possibility that drug therapy may have unintended consequences for non-target parasites and that host-parasite dynamics cannot always be fully understood in the framework of single host-parasite interactions. PMID:23658004

Pedersen, Amy B; Antonovics, Janis

2013-08-23

151

mRNA-Seq and microarray development for the Grooved carpet shell clam, Ruditapes decussatus: a functional approach to unravel host -parasite interaction  

PubMed Central

Background The Grooved Carpet shell clam Ruditapes decussatus is the autochthonous European clam and the most appreciated from a gastronomic and economic point of view. The production is in decline due to several factors such as Perkinsiosis and habitat invasion and competition by the introduced exotic species, the manila clam Ruditapes philippinarum. After we sequenced R. decussatus transcriptome we have designed an oligo microarray capable of contributing to provide some clues on molecular response of the clam to Perkinsiosis. Results A database consisting of 41,119 unique transcripts was constructed, of which 12,479 (30.3%) were annotated by similarity. An oligo-DNA microarray platform was then designed and applied to profile gene expression in R. decussatus heavily infected by Perkinsus olseni. Functional annotation of differentially expressed genes between those two conditionswas performed by gene set enrichment analysis. As expected, microarrays unveil genes related with stress/infectious agents such as hydrolases, proteases and others. The extensive role of innate immune system was also analyzed and effect of parasitosis upon expression of important molecules such as lectins reviewed. Conclusions This study represents a first attempt to characterize Ruditapes decussatus transcriptome, an important marine resource for the European aquaculture. The trancriptome sequencing and consequent annotation will increase the available tools and resources for this specie, introducing the possibility of high throughput experiments such as microarrays analysis. In this specific case microarray approach was used to unveil some important aspects of host-parasite interaction between the Carpet shell clam and Perkinsus, two non-model species, highlighting some genes associated with this interaction. Ample information was obtained to identify biological processes significantly enriched among differentially expressed genes in Perkinsus infected versus non-infected gills. An overview on the genes related with the immune system on R. decussatus transcriptome is also reported. PMID:24168212

2013-01-01

152

Comparative population structure and genetic diversity of Arceuthobium americanum (Viscaceae) and its Pinus host species: insight into host-parasite evolution in parasitic angiosperms.  

PubMed

In a recent study we revealed that the parasitic angiosperm Arceuthobium americanum is comprised of three distinct genetic races, each associated with a different host in regions of allopatry. In order to assess the role of host identity and geographical isolation on race formation in A. americanum, we compared the genetic population structure of this parasite with that of its three principal hosts, Pinus banksiana, Pinus contorta var. latifolia and Pinus contorta var. murrayana. Despite the fact that A. americanum was divided into three genetic races, hosts were divided into only two genetic groups: (i) Pinus banksiana and hybrids, and (ii) P. contorta var. latifolia and var. murrayana. These findings suggest that factors such as geographical isolation and adaptation to different environmental conditions are important for race formation in the absence of host-driven selection pressures. To assess factors impacting population structure at the fine-scale, genetic and geographical distance matrices of host and parasite were compared within A. americanum races. The lack of a relationship between genetic and geographical distance matrices suggests that isolation-by-distance plays a negligible role at this level. The effect of geographical isolation may have been diminished because of the influence of factors such as random seed dispersal by animal vectors or adaptation to nongeographically patterned environmental conditions. Host-parasite interactions might also have impacted the fine-scale structure of A. americanum because the parasite and host were found to have similar patterns of gene flow. PMID:11928707

Jerome, Cheryl A; Ford, Bruce A

2002-03-01

153

Impact of host nutritional status on infection dynamics and parasite virulence in a bird-malaria system.  

PubMed

Host resources can drive the optimal parasite exploitation strategy by offering a good or a poor environment to pathogens. Hosts living in resource-rich habitats might offer a favourable environment to developing parasites because they provide a wealth of resources. However, hosts living in resource-rich habitats might afford a higher investment into costly immune defences providing an effective barrier against infection. Understanding how parasites can adapt to hosts living in habitats of different quality is a major challenge in the light of the current human-driven environmental changes. We studied the role of nutritional resources as a source of phenotypic variation in host exploitation by the avian malaria parasite Plasmodium relictum. We investigated how the nutritional status of birds altered parasite within-host dynamics and virulence, and how the interaction between past and current environments experienced by the parasite accounts for the variation in the infection dynamics. Experimentally infected canaries were allocated to control or supplemented diets. Plasmodium parasites experiencing the two different environments were subsequently transmitted in a full-factorial design to new hosts reared under similar control or supplemented diets. Food supplementation was effective since supplemented hosts gained body mass during a 15-day period that preceded the infection. Host nutrition had strong effects on infection dynamics and parasite virulence. Overall, parasites were more successful in control nonsupplemented birds, reaching larger population sizes and producing more sexual (transmissible) stages. However, supplemented hosts paid a higher cost of infection, and when keeping parasitaemia constant, they had lower haematocrit than control hosts. Parasites grown on control hosts were better able to exploit the subsequent hosts since they reached higher parasitaemia than parasites originating from supplemented hosts. They were also more virulent since they induced higher mass and haematocrit loss. Our study highlights that parasite virulence can be shaped by the host nutritional status and that parasite can adapt to the environment provided by their hosts, possibly through genetic selection. PMID:23926945

Cornet, Stphane; Bichet, Coraline; Larcombe, Stephen; Faivre, Bruno; Sorci, Gabriele

2014-01-01

154

Host-parasite coevolution and optimal mutation rates for semiconservative quasispecies.  

PubMed

In this paper, we extend a model of host-parasite coevolution to incorporate the semiconservative nature of DNA replication for both the host and the parasite. We find that the optimal mutation rate for the semiconservative and conservative hosts converge for realistic genome lengths, thus maintaining the admirable agreement between theory and experiment found previously for the conservative model and justifying the conservative approximation in some cases. We demonstrate that, while the optimal mutation rate for a conservative and semiconservative parasite interacting with a given immune system is similar to that of a conservative parasite, the properties away from this optimum differ significantly. We suspect that this difference, coupled with the requirement that a parasite optimize survival in a range of viable hosts, may help explain why semiconservative viruses are known to have significantly lower mutation rates than their conservative counterparts. PMID:15244619

Brumer, Yisroel; Shakhnovich, Eugene I

2004-06-01

155

Disentangling the influence of parasite genotype, host genotype and maternal environment on different stages of bacterial infection in Daphnia magna.  

PubMed

Individuals naturally vary in the severity of infectious disease when exposed to a parasite. Dissecting this variation into genetic and environmental components can reveal whether or not this variation depends on the host genotype, parasite genotype or a range of environmental conditions. Complicating this task, however, is that the symptoms of disease result from the combined effect of a series of events, from the initial encounter between a host and parasite, through to the activation of the host immune system and the exploitation of host resources. Here, we use the crustacean Daphnia magna and its parasite Pasteuria ramosa to show how disentangling genetic and environmental factors at different stages of infection improves our understanding of the processes shaping infectious disease. Using compatible host-parasite combinations, we experimentally exclude variation in the ability of a parasite to penetrate the host, from measures of parasite clearance, the reduction in host fecundity and the proliferation of the parasite. We show how parasite resistance consists of two components that vary in environmental sensitivity, how the maternal environment influences all measured aspects of the within-host infection process and how host-parasite interactions following the penetration of the parasite into the host have a distinct temporal component. PMID:22593109

Hall, Matthew D; Ebert, Dieter

2012-08-22

156

Disentangling the influence of parasite genotype, host genotype and maternal environment on different stages of bacterial infection in Daphnia magna  

PubMed Central

Individuals naturally vary in the severity of infectious disease when exposed to a parasite. Dissecting this variation into genetic and environmental components can reveal whether or not this variation depends on the host genotype, parasite genotype or a range of environmental conditions. Complicating this task, however, is that the symptoms of disease result from the combined effect of a series of events, from the initial encounter between a host and parasite, through to the activation of the host immune system and the exploitation of host resources. Here, we use the crustacean Daphnia magna and its parasite Pasteuria ramosa to show how disentangling genetic and environmental factors at different stages of infection improves our understanding of the processes shaping infectious disease. Using compatible hostparasite combinations, we experimentally exclude variation in the ability of a parasite to penetrate the host, from measures of parasite clearance, the reduction in host fecundity and the proliferation of the parasite. We show how parasite resistance consists of two components that vary in environmental sensitivity, how the maternal environment influences all measured aspects of the within-host infection process and how hostparasite interactions following the penetration of the parasite into the host have a distinct temporal component. PMID:22593109

Hall, Matthew D.; Ebert, Dieter

2012-01-01

157

Progress in parasitic plant biology: host selection and nutrient transfer.  

PubMed

Host range varies widely among species of parasitic plants. Parasitic plants realize host selection through induction by chemical molecular signals, including germination stimulants and haustoria-inducing factors (HIFs). Research on parasitic plant biology has provided information on germination, haustorium induction, invasion, and haustorial structures and functions. To date, some molecular mechanisms have been suggested to explain how germination stimulants work, involving a chemical change caused by addition of a nucleophilic protein receptor, and direct or indirect stimulation of ethylene generation. Haustorium initiation is induced by HIFs that are generated by HIF-releasing enzymes from the parasite or triggered by redox cycling between electrochemical states of the inducers. Haustorium attachment is non-specific, however, the attachment to a host is facilitated by mucilaginous substances produced by haustorial hairs. Following the attachment, the intrusive cells of parasites penetrate host cells or push their way through the host epidermis and cortex between host cells, and some types of cell wall-degrading enzymes may assist in the penetration process. After the establishment of host-parasite associations, parasitic plants develop special morphological structures (haustoria) and physiological characteristics, such as high transpiration rates, high leaf conductance, and low water potentials in hemiparasites, for nutrient transfer and resource acquisition from their hosts. Therefore, they negatively affect the growth and development and even cause death of their hosts. PMID:16547862

Shen, H; Ye, W; Hong, L; Huang, H; Wang, Z; Deng, X; Yang, Q; Xu, Z

2006-03-01

158

Retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs.  

PubMed

Why do many hosts accept costly avian brood parasitism even when parasitic eggs and nestlings differ dramatically in appearance from their own? Scientists argue that evolutionary lag or equilibrium can explain this evolutionary enigma. Few, however, consider the potential of parasitic birds to enforce acceptance by destroying eggs or nestlings of hosts that eject parasitic eggs and thereby reject parasitism. This retaliatory "mafia" behavior has been reported in one species of parasitic cuckoo but never in parasitic cowbirds. Here we present experimental evidence of mafia behavior in the brown-headed cowbird (Molothrus ater), a widely distributed North American brood parasite. We manipulated ejection of cowbird eggs and cowbird access to predator-proof nests in a common host to test experimentally for mafia behavior. When cowbird access was allowed, 56% of "ejector" nests were depredated compared with only 6% of "accepter" nests. No nests were destroyed when cowbird access was always denied or when access was denied after we removed cowbird eggs, indicating that cowbirds were responsible. Nonparasitized nests were depredated at an intermediate rate (20%) when cowbirds were allowed access, suggesting that cowbirds may occasionally "farm" hosts to create additional opportunities for parasitism. Cowbirds parasitized most (85%) renests of the hosts whose nests were depredated. Ejector nests produced 60% fewer host offspring than accepter nests because of the predatory behavior attributed to cowbirds. Widespread predatory behaviors in cowbirds could slow the evolution of rejection behaviors and further threaten populations of some of the >100 species of regular cowbird hosts. PMID:17360549

Hoover, Jeffrey P; Robinson, Scott K

2007-03-13

159

Retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs  

PubMed Central

Why do many hosts accept costly avian brood parasitism even when parasitic eggs and nestlings differ dramatically in appearance from their own? Scientists argue that evolutionary lag or equilibrium can explain this evolutionary enigma. Few, however, consider the potential of parasitic birds to enforce acceptance by destroying eggs or nestlings of hosts that eject parasitic eggs and thereby reject parasitism. This retaliatory mafia behavior has been reported in one species of parasitic cuckoo but never in parasitic cowbirds. Here we present experimental evidence of mafia behavior in the brown-headed cowbird (Molothrus ater), a widely distributed North American brood parasite. We manipulated ejection of cowbird eggs and cowbird access to predator-proof nests in a common host to test experimentally for mafia behavior. When cowbird access was allowed, 56% of ejector nests were depredated compared with only 6% of accepter nests. No nests were destroyed when cowbird access was always denied or when access was denied after we removed cowbird eggs, indicating that cowbirds were responsible. Nonparasitized nests were depredated at an intermediate rate (20%) when cowbirds were allowed access, suggesting that cowbirds may occasionally farm hosts to create additional opportunities for parasitism. Cowbirds parasitized most (85%) renests of the hosts whose nests were depredated. Ejector nests produced 60% fewer host offspring than accepter nests because of the predatory behavior attributed to cowbirds. Widespread predatory behaviors in cowbirds could slow the evolution of rejection behaviors and further threaten populations of some of the >100 species of regular cowbird hosts. PMID:17360549

Hoover, Jeffrey P.; Robinson, Scott K.

2007-01-01

160

Parasite transmission in complex communities: predators and alternative hosts alter pathogenic infections in amphibians.  

PubMed

While often studied in isolation, host-parasite interactions are typically embedded within complex communities. Other community members, including predators and alternative hosts, can therefore alter parasite transmission (e.g., the dilution effect), yet few studies have experimentally evaluated more than one such mechanism. Here, we used data from natural wetlands to design experiments investigating how alternative hosts and predators of parasites mediate trematode (Ribeiroia ondatrae) infection in a focal amphibian host (Pseudacris regilla). In short-term predation bioassays involving mollusks, zooplankton, fish, larval insects, or newts, four of seven tested species removed 62-93% of infectious stages. In transmission experiments, damselfly nymphs (predators) and newt larvae (alternative hosts) reduced infection in P. regilla tadpoles by -50%, whereas mosquitofish (potential predators and alternative hosts) did not significantly influence transmission. Additional bioassays indicated that predators consumed parasites even in the presence of alternative prey. In natural wetlands, newts had similar infection intensities as P. regilla, suggesting that they commonly function as alternative hosts despite their unpalatability to downstream hosts, whereas mosquitofish had substantially lower infection intensities and are unlikely to function as hosts. These results underscore the importance of studying host-parasite interactions in complex communities and of broadly linking research on predation, biodiversity loss, and infectious diseases. PMID:22834364

Orlofske, Sarah A; Jadin, Robert C; Preston, Daniel L; Johnson, Pieter T J

2012-06-01

161

Against all odds: Explaining high host specificity in dispersal-prone parasites  

Microsoft Academic Search

Host specificity gauges the degree to which a parasite occurs in association with a single host species. The measure is indicative of properties of the host and parasite, as well as their ecological and co-evolutionary relationships. Host specificity is influenced by the behavior and ecology of both parasite and host. Where parasites are active, vagile and coupled with hosts whose

Carl W. Dick; Bruce D. Patterson

2007-01-01

162

Long-term coevolution between avian brood parasites and their hosts.  

PubMed

Coevolutionary theory predicts that the most common long-term outcome of the relationships between brood parasites and their hosts should be coevolutionary cycles based on a dynamic change selecting the currently least-defended host species, given that when well-defended hosts are abandoned, hosts will be selected to decrease their defences as these are usually assumed to be costly. This is assumed to be the case also in brood parasite-host systems. Here I examine the frequency of the three potential long-term outcomes of brood parasite-host coevolution (coevolutionary cycles, lack of rejection, and successful resistance) in 182 host species. The results of simple exploratory comparisons show that coevolutionary cycles are very scarce while the lack of rejection and successful resistance, which are considered evolutionary enigmas, are much more frequent. I discuss these results considering (i) the importance of different host defences at all stages of the breeding cycle, (ii) the role of phenotypic plasticity in long-term coevolution, and (iii) the evolutionary history of host selection. I suggest that in purely antagonistic coevolutionary interactions, such as those involving brood parasites and their hosts, that although cycles will exist during an intermediate phase of the interactions, the arms race will end with the extinction of the host or with the host acquiring successful resistance. As evolutionary time passes, this resistance will force brood parasites to use previously less suitable host species. Furthermore, I present a model that represents the long-term trajectories and outcomes of coevolutionary interactions between brood parasites and their hosts with respect to the evolution of egg-rejection defence. This model suggests that as an increasing number of species acquire successful resistance, other unparasitized host species become more profitable and their parasitism rate and the costs imposed by brood parasitism at the population level will increase, selecting for the evolution of host defences. This means that although acceptance is adaptive when the parasitism rate and the costs of parasitism are very low, this cannot be considered to represent an evolutionary equilibrium, as conventional theory has done to date, because it is not stable. PMID:24330159

Soler, Manuel

2014-08-01

163

Association between host's genetic diversity and parasite burden in damselflies.  

PubMed

Recent research indicates that low genetic variation in individuals can increase susceptibility to parasite infection, yet evidence from natural invertebrate populations remains scarce. Here, we studied the relationship between genetic heterozygosity, measured as AFLP-based inbreeding coefficient fAFLP , and gregarine parasite burden from eleven damselfly, Calopteryx splendens, populations. We found that in the studied populations, 5-92% of males were parasitized by endoparasitic gregarines (Apicomplexa: Actinocephalidae). Number of parasites ranged from none to 47 parasites per male, and parasites were highly aggregated in a few hosts. Mean individual fAFLP did not differ between populations. Moreover, we found a positive association between individual's inbreeding coefficient and parasite burden. In other words, the more homozygous the individual, the more parasites it harbours. Thus, parasites are likely to pose strong selection pressure against inbreeding and homozygosity. Our results support the heterozygosity-fitness correlation hypothesis, which suggests the importance of heterozygosity for an individual's pathogen resistance. PMID:23865399

Kaunisto, K M; Viitaniemi, H M; Leder, E H; Suhonen, J

2013-08-01

164

A matching-allele model explains host resistance to parasites.  

PubMed

The maintenance of genetic variation and sex despite its costs has long puzzled biologists. A popular idea, the Red Queen Theory, is that under rapid antagonistic coevolution between hosts and their parasites, the formation of new rare host genotypes through sex can be advantageous as it creates host genotypes to which the prevailing parasite is not adapted. For host-parasite coevolution to lead to an ongoing advantage for rare genotypes, parasites should infect specific host genotypes and hosts should resist specific parasite genotypes. The most prominent genetics capturing such specificity are matching-allele models (MAMs), which have the key feature that resistance for two parasite genotypes can reverse by switching one allele at one host locus. Despite the lack of empirical support, MAMs have played a central role in the theoretical development of antagonistic coevolution, local adaptation, speciation, and sexual selection. Using genetic crosses, we show that resistance of the crustacean Daphnia magna against the parasitic bacterium Pasteuria ramosa follows a MAM. Simulation results show that the observed genetics can explain the maintenance of genetic variation and contribute to the maintenance of sex in the facultatively sexual host as predicted by the Red Queen Theory. PMID:23707426

Luijckx, Pepijn; Fienberg, Harris; Duneau, David; Ebert, Dieter

2013-06-17

165

Attachment of the parasitic weed dodder to the host  

Microsoft Academic Search

Summary.?The parasitic weed dodder (Cuscuta pentagona L.) invades a number of potential host species, but the mechanisms responsible for ensuring tight adhesion to the wide variety\\u000a of host surfaces have yet to be identified. In this study, a battery of microscopy protocols is used to examine the hostparasite\\u000a interface in an effort to deduce these mechanisms. As the dodder shoot

K. C. Vaughn

2002-01-01

166

Brood parasite eggs enhance egg survivorship in a multiply parasitized host  

PubMed Central

Despite the costs to avian parents of rearing brood parasitic offspring, many species do not reject foreign eggs from their nests. We show that where multiple parasitism occurs, rejection itself can be costly, by increasing the risk of host egg loss during subsequent parasite attacks. Chalk-browed mockingbirds (Mimus saturninus) are heavily parasitized by shiny cowbirds (Molothrus bonariensis), which also puncture eggs in host nests. Mockingbirds struggle to prevent cowbirds puncturing and laying, but seldom remove cowbird eggs once laid. We filmed cowbird visits to nests with manipulated clutch compositions and found that mockingbird eggs were more likely to escape puncture the more cowbird eggs accompanied them in the clutch. A Monte Carlo simulation of this dilution effect, comparing virtual hosts that systematically either reject or accept parasite eggs, shows that acceptors enjoy higher egg survivorship than rejecters in host populations where multiple parasitism occurs. For mockingbirds or other hosts in which host nestlings fare well in parasitized broods, this benefit might be sufficient to offset the fitness cost of rearing parasite chicks, making egg acceptance evolutionarily stable. Thus, counterintuitively, high intensities of parasitism might decrease or even reverse selection pressure for host defence via egg rejection. PMID:22158956

Gloag, Ros; Fiorini, Vanina D.; Reboreda, Juan C.; Kacelnik, Alex

2012-01-01

167

Distinct Lineages of Schistocephalus Parasites in Threespine and Ninespine Stickleback Hosts Revealed by DNA Sequence Analysis  

PubMed Central

Parasitic interactions are often part of complex networks of interspecific relationships that have evolved in biological communities. Despite many years of work on the evolution of parasitism, the likelihood that sister taxa of parasites can co-evolve with their hosts to specifically infect two related lineages, even when those hosts occur sympatrically, is still unclear. Furthermore, when these specific interactions occur, the molecular and physiological basis of this specificity is still largely unknown. The presence of these specific parasitic relationships can now be tested using molecular markers such as DNA sequence variation. Here we test for specific parasitic relationships in an emerging host-parasite model, the stickleback-Schistocephalus system. Threespine and ninespine stickleback fish are intermediate hosts for Schistocephalus cestode parasites that are phenotypically very similar and have nearly identical life cycles through plankton, stickleback, and avian hosts. We analyzed over 2000 base pairs of COX1 and NADH1 mitochondrial DNA sequences in 48 Schistocephalus individuals collected from threespine and ninespine stickleback hosts from disparate geographic regions distributed across the Northern Hemisphere. Our data strongly support the presence of two distinct clades of Schistocephalus, each of which exclusively infects either threespine or ninespine stickleback. These clades most likely represent different species that diverged soon after the speciation of their stickleback hosts. In addition, genetic structuring exists among Schistocephalus taken from threespine stickleback hosts from Alaska, Oregon and Wales, although it is much less than the divergence between hosts. Our findings emphasize that biological communities may be even more complex than they first appear, and beg the question of what are the ecological, physiological, and genetic factors that maintain the specificity of the Schistocephalus parasites and their stickleback hosts. PMID:21811623

Nishimura, Nicole; Heins, David C.; Andersen, Ryan O.; Barber, Iain; Cresko, William A.

2011-01-01

168

Within-host competition and diversification of macro-parasites  

PubMed Central

Although competitive speciation is more and more regarded as a plausible mechanism for sympatric speciation of non-parasite species, virtually no empirical or theoretical study has considered this evolutionary process to explain intra-host diversification of parasites. We expanded the theory of competitive speciation to parasite species looking at the effect of macro-parasite life history on the conditions for sympatric speciation under the so-called pleiotropic scenario. We included within-host competition in the classical Anderson and May framework assuming that individuals exploit within-host resources according to a quantitative trait. We derived the invasion fitness function of mutants considering different distributions of individuals among hosts. Although the mutant fitness depends on parameters describing the key features of macro-parasite life history, and on the relative distributions of mutant and residents in hosts, the conditions for competitive speciation of macro-parasites are exactly the same as those previously established for free-living species. As an interesting by-product, within-host competitive speciation is expected not to depend on the aggregation level of the parasites. This theoretical pattern is confirmed by comparing the speciation rate of weakly and strongly aggregated monogenean parasites. PMID:22696483

Guilhem, Rascalou; imkov, Andrea; Morand, Serge; Gourbire, Sbastien

2012-01-01

169

Cross-kingdom host shifts of phytomyxid parasites  

PubMed Central

Background Phytomyxids (plasmodiophorids and phagomyxids) are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. Plasmodiophorids are best known as pathogens or vectors for viruses of arable crops (e.g. clubroot in brassicas, powdery potato scab, and rhizomania in sugar beet). Some phytomyxid parasites are of considerable economic and ecologic importance globally, and their hosts include important species in marine and terrestrial environments. However most phytomyxid diversity remains uncharacterised and knowledge of their relationships with host taxa is very fragmentary. Results Our molecular and morphological analyses of phytomyxid isolatesincluding for the first time oomycete and sea-grass parasitesdemonstrate two cross-kingdom host shifts between closely related parasite species: between angiosperms and oomycetes, and from diatoms/brown algae to angiosperms. Switching between such phylogenetically distant hosts is generally unknown in host-dependent eukaryote parasites. We reveal novel plasmodiophorid lineages in soils, suggesting a much higher diversity than previously known, and also present the most comprehensive phytomyxid phylogeny to date. Conclusion Such large-scale host shifts between closely related obligate biotrophic eukaryote parasites is to our knowledge unique to phytomyxids. Phytomyxids may readily adapt to a wide diversity of new hosts because they have retained the ability to covertly infect alternative hosts. A high cryptic diversity and ubiquitous distribution in agricultural and natural habitats implies that in a changing environment phytomyxids could threaten the productivity of key species in marine and terrestrial environments alike via host shift speciation. PMID:24559266

2014-01-01

170

Host-specific races in the holoparasitic angiosperm Orobanche minor: implications for speciation in parasitic plants  

PubMed Central

Background and Aims Orobanche minor is a root-holoparasitic angiosperm that attacks a wide range of host species, including a number of commonly cultivated crops. The extent to which genetic divergence among natural populations of O. minor is influenced by host specificity has not been determined previously. Here, the host specificity of natural populations of O. minor is quantified for the first time, and evidence that this species may comprise distinct physiological races is provided. Methods A tripartite approach was used to examine the physiological basis for the divergence of populations occurring on different hosts: (1) hostparasite interactions were cultivated in rhizotron bioassays in order to quantify the early stages of the infection and establishment processes; (2) using reciprocal-infection experiments, parasite races were cultivated on their natural and alien hosts, and their fitness determined in terms of biomass; and (3) the anatomy of the hostparasite interface was investigated using histochemical techniques, with a view to comparing the infection process on different hosts. Key Results Races occurring naturally on red clover (Trifolium pratense) and sea carrot (Daucus carota ssp. gummifer) showed distinct patterns of host specificity: parasites cultivated in cross-infection studies showed a higher fitness on their natural hosts, suggesting that races show local adaptation to specific hosts. In addition, histological evidence suggests that clover and carrot roots vary in their responses to infection. Different root anatomy and responses to infection may underpin a physiological basis for host specificity. Conclusions It is speculated that host specificity may isolate races of Orobanche on different hosts, accelerating divergence and ultimately speciation in this genus. The rapid life cycle and broad host range of O. minor make this species an ideal model with which to study the interactions of parasitic plants with their host associates. PMID:19251714

Thorogood, C. J.; Rumsey, F. J.; Hiscock, S. J.

2009-01-01

171

A sensory code for host seeking in parasitic nematodes  

PubMed Central

Summary Nematodes comprise a large phylum of both free-living and parasitic species that show remarkably diverse lifestyles, ecological niches, and behavioral repertoires. Parasitic species in particular often display highly specialized host-seeking behaviors that reflect their specific host preferences. Many host-seeking behaviors can be triggered by the presence of host odors, yet little is known about either the specific olfactory cues that trigger these behaviors or the neural circuits that underlie them. Heterorhabditis bacteriophora and Steinernema carpocapsae are phylogenetically distant insect-parasitic nematodes whose host-seeking and host-invasion behavior resembles that of some of the most devastating human- and plant-parasitic nematodes. Here we compare the olfactory responses of H. bacteriophora and S. carpocapsae infective juveniles (IJs) to those of Caenorhabditis elegans dauers, which are analogous life stages [1]. We show that the broad host range of these parasites results from their ability to respond to the universally-produced signal carbon dioxide (CO2) as well as a wide array of odors, including host-specific odors that we identified using TD-GC-MS. We show that CO2 is attractive for the parasitic IJs and C. elegans dauers despite being repulsive for C. elegans adults [24], and we identify an ancient and conserved sensory neuron that mediates CO2 response in both parasitic and free-living species regardless of whether CO2 is an attractive or a repulsive cue. Finally, we show that the parasites odor response profiles are more similar to each other than to that of C. elegans despite their greater phylogenetic distance, likely reflecting evolutionary convergence to insect parasitism. Our results suggest that the olfactory responses of parasitic versus free-living nematodes are highly diverse and that this diversity is critical to the evolution of nematode behavior. PMID:21353558

Hallem, Elissa A.; Dillman, Adler R.; Hong, Annie V.; Zhang, Yuanjun; Yano, Jessica M.; DeMarco, Stephanie F.

2011-01-01

172

Suppression of Host Photosynthesis by the Parasitic Plant Rhinanthus minor  

PubMed Central

Background and Aims Parasitism is well understood to have wide-ranging deleterious effects on host performance in species thus far characterized. Photosynthetic performance reductions have been noted in the StrigaZea mays association; however, no such information exists for facultative hemiparasitic plants and their hosts, nor are the effects of host species understood. Methods Chlorophyll fluorimetry was used to study the effects of parasitism by the hemiparasite Rhinanthus minor on the grass Phleum bertolinii and the forb Plantago lanceolata, and the effects of host species on the photosynthetic apparatus of R. minor. Key Results Parasitism by Rhinanthus led to a significant decrease in the host, and total (host + parasite) biomass in Phleum; however, in Plantago, no significant repression of growth was noted. Maximum quantum yield (Fv/Fm) was reduced in parasitized Plantago, relative to control plants, but not in Phleum. Fv/Fm was significantly lower in R. minor parasitizing Phleum than Plantago, suggesting Phleum to be a superior host to Plantago for R. minor. Steady-state quantum yield (?PSII) was significantly depressed in parasitized Phleum, but only at low irradiances in Plantago. ?PSII was very low for R. minor grown on Plantago, but not Phleum. Conclusions Shown here is the first evidence of the suppression of host photosynthesis by a facultative hemiparasitic plant, which has significant effects on total biomass production. Host identity is a significant factor in parasite success, with the forb Plantago lanceolata exhibiting apparent chemical as well as previously identified physical defences to parasitism. It is proposed that the electron transport rate (as denoted by ?PSII) represents the limiting factor for biomass accumulation in this system, and that Plantago is able to suppress the growth of Rhinanthus by suppressing the electron transport rate. PMID:18211886

Cameron, Duncan D.; Geniez, Jean-Michelle; Seel, Wendy E.; Irving, Louis J.

2008-01-01

173

Interactions between hemiparasitic plants and their hosts  

PubMed Central

Hemiparasitic plants display a unique strategy of resource acquisition combining parasitism of other species and own photosynthetic activity. Despite the active photoassimilation and green habit, they acquire substantial amount of carbon from their hosts. The organic carbon transfer has a crucial influence on the nature of the interaction between hemiparasites and their hosts which can oscillate between parasitism and competition for light. In this minireview, we summarize methodical approaches and results of various studies dealing with carbon budget of hemiparasites and the ecological implications of carbon heterotrophy in hemiparasites. PMID:20729638

Plavcov, Lenka; Cameron, Duncan D

2010-01-01

174

A novel method of rejection of brood parasitic eggs reduces parasitism intensity in a cowbird host  

PubMed Central

The hosts of brood parasitic birds are under strong selection pressure to recognize and remove foreign eggs from their nests, but parasite eggs may be too large to be grasped whole and too strong to be readily pierced by the host's bill. Such operating constraints on egg removal are proposed to force some hosts to accept parasite eggs, as the costs of deserting parasitized clutches can outweigh the cost of rearing parasites. By fitting microcameras inside nests, we reveal that the Neotropical baywing (Agelaioides badius), a host of the screaming cowbird (Molothrus rufoaxillaris) and shiny cowbird (Molothrus bonariensis), instead circumvents such constraints by kicking parasite eggs out of the nest. To our knowledge, this is the first report of a passerine bird using its feet to remove objects from the nest. Kick-ejection was an all-or-nothing response. Baywings kick-ejected parasite eggs laid before their own first egg and, if heavily parasitized, they ejected entire clutches and began again in the same nest. Few baywings were able to rid their nests of every parasite egg, but their novel ejection method allowed them to reduce the median parasitism intensity by 75 per cent (from four to one cowbird eggs per nest), providing an effective anti-parasite defence. PMID:23485877

De Mrsico, Mara C.; Gloag, Ros; Ursino, Cynthia A.; Reboreda, Juan C.

2013-01-01

175

Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants  

PubMed Central

Background Parasite heterogeneity and within-host competition are thought to be important factors influencing the dynamics of host-parasite relationships. Yet, while there have been many theoretical investigations of how these factors may act, empirical data is more limited. We investigated the effects of parasite density and heterogeneity on parasite virulence and fitness using four strains of the entomopathogenic fungus, Metarhizium anisopliae var. anisopliae, and its leaf-cutting ant host Acromyrmex echinatior as the model system. Results The relationship between parasite density and infection was sigmoidal, with there being an invasion threshold for an infection to occur (an Allee effect). Although spore production was positively density-dependent, parasite fitness decreased with increasing parasite density, indicating within-host scramble competition. The dynamics differed little between the four strains tested. In mixed infections of three strains the infection-growth dynamics were unaffected by parasite heterogeneity. Conclusions The strength of within-host competition makes dispersal the best strategy for the parasite. Parasite heterogeneity may not have effected virulence or the infection dynamics either because the most virulent strain outcompeted the others, or because the interaction involved scramble competition that was impervious to parasite heterogeneity. The dynamics observed may be common for virulent parasites, such as Metarhizium, that produce aggregated transmission stages. Such parasites make useful models for investigating infection dynamics and the impact of parasite competition. PMID:15541185

Hughes, William OH; Petersen, Klaus S; Ugelvig, Line V; Pedersen, Dorthe; Thomsen, Lene; Poulsen, Michael; Boomsma, Jacobus J

2004-01-01

176

Hosts improve the reliability of chick recognition by delaying the hatching of brood parasitic eggs.  

PubMed

The reliability of information that animals use to make decisions has fitness consequences. Accordingly, selection should favor the evolution of strategies that enhance the reliability of information used in learning and decision making. For example, hosts of avian brood parasites should be selected to increase the reliability of the information they use to learn to recognize their own eggs and chicks. The American coot (Fulica americana), a conspecific brood parasite, uses cues learned from the first-hatched chicks of each brood to recognize and reject parasitic chicks. However, if parasitic eggs are among the first to hatch, recognition cues are confounded and parents then fail to distinguish parasitic chicks from their own chicks. Therefore, hosts could ensure correct chick recognition by delaying parasitic eggs from hatching until after the first host eggs. Here we demonstrate that discriminatory incubation, whereby coots specifically delay the hatching of parasitic eggs, improves the reliability of parasitic chick recognition. In effect, coots gain fitness benefits by enhancing the reliability of information they later use for learning. Our study shows that a positive interaction between two host adaptations in coots--egg recognition and chick recognition--increases the overall effectiveness of host defense. PMID:21396823

Shizuka, Daizaburo; Lyon, Bruce E

2011-03-22

177

When should a trophically transmitted parasite manipulate its host?  

PubMed

We investigate evolution of two categories of adaptive host manipulation by trophically transmitted helminths: (1) predation suppression decreases the host's mortality before the helminth is capable of establishing in its next host; (2) predation enhancement increases the existing host's mortality after it can establish in its next host. If all parasite mortality is purely random (time-independent), enhancement must increase predation by the next host sufficiently more (depending on manipulative costs) than it increases the average for all forms of host mortality; thus if host and parasite die only through random predation, manipulation must increase the "right" predation more than the "wrong" predation. But if almost all parasites die in their intermediate host through reaching the end of a fixed life span, enhancement can evolve if it increases the right predation, regardless of how much it attracts wrong predators. Although enhancement is always most favorable when it targets the right host, suppression aids survival to the time when establishment in the next host is possible: it is most favorable if it reduces all aspects of host (and hence parasite) mortality. If constrained to have selective effects, suppression should reduce the commonest form of mortality. PMID:19154358

Parker, Geoffrey A; Ball, Michael A; Chubb, James C; Hammerschmidt, Katrin; Milinski, Manfred

2009-02-01

178

Suppression of Host Photosynthesis by the Parasitic Plant Rhinanthus minor  

Microsoft Academic Search

Background and Aims Parasitism is well understood to have wide-ranging deleterious effects on host performance in species thus far characterized. Photosynthetic performance reductions have been noted in the Striga - Zea mays association; however, no such information exists for facultative hemiparasitic plants and their hosts, nor are the effects of host species understood. Methods Chlorophyll fluorimetry was used

DUNCAN D. CAMERON; J EAN-MICHELLE G ENIEZ; W ENDY E. S EEL

2008-01-01

179

RNA translocation between parasitic plants and their hosts.  

PubMed

Recent research indicates that RNA translocation occurs between certain parasitic plant species and their hosts. The movement of at least 27 mRNAs has been demonstrated between hosts and Cuscuta pentagona Engelm., with the largest proportion of these being regulatory genes. Movement of RNAi signals has been documented from hosts to the parasites Triphysaria versicolor (Frisch & CA Mey) and Orobanche aegyptiaca (Pers.), demonstrating that the regulation of genes in one species can be influenced by transfer of RNA signals through a parasitic association. This review considers the implications of these findings in light of present understanding of host-parasite connections and the growing body of evidence that RNAs are able to act as signal molecules that convey regulatory information in a cell- and tissue-specific manner. Together, this suggests that parasitic plants can exchange RNAs with their hosts, and that this may be part of the coordinated growth and development that occurs during the process of parasitism. This phenomenon offers promise for new insights into parasitic plants, and new opportunities for the control of parasitic weeds. PMID:19253417

Westwood, James H; Roney, Jeannine K; Khatibi, Piyum A; Stromberg, Verlyn K

2009-05-01

180

Parasite-induced aggression and impaired contest ability in a fish host  

PubMed Central

Background Success of trophically transmitted parasites depends to a great extent on their ability to manipulate their intermediate hosts in a way that makes them easier prey for target hosts. Parasite-induced behavioural changes are the most spectacular and diverse examples of manipulation. Most of the studies have been focused on individual behaviour of hosts including fish. We suggest that agonistic interactions and territoriality in fish hosts may affect their vulnerability to predators and thus the transmission efficiency of trophically transmitted parasites. The parasite Diplostomum spathaceum (Trematoda) and juvenile rainbow trout, Oncorhynchus mykiss, were used to study whether infection can alter aggression rates and territorial behaviour of intermediate fish hosts. Results The changes in behaviour of rainbow trout, Oncorhynchus mykiss, infected with an eye fluke Diplostomum spathaceum (Trematoda), was monitored over the course of an experimental infection for 1.5 months. At the beginning of their development, not yet infective D. spathaceum metacercariae decreased the aggressiveness of rainbow trout. By the time that metacercariae were fully infective to their definitive hosts, the aggressiveness increased and exceeded that of control fish. Despite the increased aggressiveness, the experimentally infected fish lost contests for a territory (dark parts of the bottom) against the control fish. Conclusions The results obtained indicate that the parasitized fish pay the cost of aggressiveness without the benefit of acquiring a territory that would provide them with better protection against predators. This behaviour should increase transmission of the parasite as expected by the parasite manipulation hypothesis. PMID:20226098

2010-01-01

181

Disruption of a host-parasite system following the introduction of an exotic host species.  

PubMed

The potential of biological invasions to threaten native ecosystems is well recognized. Here we describe how an introduced species impacts on native host-parasite dynamics by acting as an alternative host. By sampling sites across an invasion front in Ireland, we quantified the influence of the introduced bank vole (Clethrionomys glareolus) on the epidemiology of infections caused by flea-transmitted haemoparasites of the genus Bartonella in native wood mice (Apodemus sylvaticus). Bartonella infections were detected on either side of the front but occurred exclusively in wood mice, despite being highly prevalent in both rodent species elsewhere in Europe. Bank vole introduction has, however, affected the wood mouse-Bartonella interaction, with the infection prevalence of both Bartonella birtlesii and Bartonella taylorii declining significantly with increasing bank vole density. Whilst flea prevalence in wood mice increases with wood mouse density in areas without bank voles, no such relationship is detected in invaded areas. The results are consistent with the dilution effect hypothesis. This predicts that for vector-transmitted parasites, the presence of less competent host species may reduce infection prevalence in the principal host. In addition we found a negative relationship between B. birtlesii and B. taylorii prevalences, indicating that these two microparasites may compete within hosts. PMID:15977903

Telfer, S; Bown, K J; Sekules, R; Begon, M; Hayden, T; Birtles, R

2005-06-01

182

Multi-parasite host susceptibility and multi-host parasite infectivity: a new approach of the Biomphalaria glabrata / Schistosoma mansoni compatibility  

E-print Network

1 Multi-parasite host susceptibility and multi-host parasite infectivity: a new approach mansoni strains. A total of 20 homopatric and heteropatric host- parasite combinations were tested B. glabrata strain by its "multi-parasite susceptibility phenotype" that reflects better

Boyer, Edmond

183

Patterns of gregarine parasitism in dragonflies: host, habitat, and seasonality.  

PubMed

Gregarines are ubiquitous protozoan parasites that infect arthropods worldwide. More than 1,600 gregarine species have been described, but only a small percentage of invertebrates have been surveyed for these apicomplexan parasites. Adult dragonfly populations were surveyed for gregarines at two reservoirs in Texas, USA for 2 years. Gregarine prevalence and intensity were compared intraspecifically between host genders and reservoirs, among wing loads, and through time. Of the 29 dragonfly species collected, 41% hosted gregarines. Nine of these dragonfly species were previously undocumented as hosts. Among the commonly collected hosts, prevalence ranged from 18 to 52%. Parasites were aggregated among hosts and had a median intensity of five parasites per host. Gregarines were found only in hosts exceeding a minimum wing load, indicating that gregarines are likely not transferred from the naiad to adult during emergence. Prevalence and intensity increased during both years, suggesting that gregarine oocyst viability parallels increasing host population densities and may be short-lived. Prevalence and intensity also differed between dragonfly populations at two reservoirs. Regression analyses revealed that host species, host gender, month, and year were significant explanatory variables related to gregarine prevalence and intensity. Abundant information on odonate distributions, diversity, and mating activities makes dragonfly-gregarine systems excellent avenues for ecological, evolutionary, and parasitological research. Our results emphasize the importance of considering season, hosts, and habitat when studying gregarine-dragonfly ecology. PMID:20376487

Locklin, Jason L; Vodopich, Darrell S

2010-06-01

184

Evolution of parasite virulence when host responses cause disease  

E-print Network

The trade-off hypothesis of virulence evolution rests on the assumption that infection-induced mortality is a consequence of host exploitation by parasites. This hypothesis lies at the heart of many empirical and theoretical ...

Day, Troy; Graham, Andrea; Read, Andrew F

185

A permutation test of host-parasite cospeciation.  

PubMed

We introduce a statistical method that explores host-parasite coevolution by testing the null hypothesis that hosts and their associated parasites evolved independently. This test is simple and intuitive and involves only suitable randomization of the observed data. It is not even necessary to construct host and parasite phylogenetic trees, as the test can be performed directly on distance matrices. Statistical power of the test was evaluated using simulated data consistent with the alternative hypothesis of cospeciation. Results were compared with the method of Mantel (1967) and the ParaFit method of Legendre et al. (2002). We observed that our method has greater power overall and thus a higher ability to detect cospeciation in closely related host-parasite systems. Our test was also successful when applied to the pocket gopher and chewing lice system. PMID:19329652

Hommola, Kerstin; Smith, Judith E; Qiu, Yang; Gilks, Walter R

2009-07-01

186

Parasitic castration by Xenos vesparum depends on host gender.  

PubMed

Host castration represents a mechanism used by parasites to exploit energy resources from their hosts by interfering with their reproductive development or to extend host lifespan by removing risks associated with reproductive activity. One of the most intriguing groups of parasitic castrators is represented by the insects belonging to the order Strepsiptera. The macroparasite Xenos vesparum can produce dramatic phenotypic alterations in its host, the paper wasp Polistes dominula. Parasitized female wasps have undeveloped ovaries and desert the colony without performing any social task. However, very little attention has been given to the parasitic impact of X. vesparum on the male phenotype. Here, we investigated the effects of this parasite on the sexual behaviour and the morpho-physiology of P. dominula males. We found that, differently from female wasps, parasitized males are not heavily affected by Xenos: they maintain their sexual behaviour and ability to discriminate between female castes. Furthermore, the structure of their reproductive apparatus is not compromised by the parasite. We think that our results, demonstrating that the definition of X. vesparum as a parasitoid does not apply to infected males of P. dominula, provide a new perspective to discuss and maybe reconsider the traditional view of strepsipteran parasites. PMID:24776461

Cappa, Federico; Manfredini, Fabio; Dallai, Romano; Gottardo, Marco; Beani, Laura

2014-07-01

187

ORIGINAL PAPER The evolution of host manipulation by parasites  

E-print Network

2009 ? Springer Science+Business Media B.V. 2009 Abstract Many parasites are known to manipulateORIGINAL PAPER The evolution of host manipulation by parasites: a game theory analysis William L. This manipulation must have costs. Here we explore the combined effects of three such costs on the amount of effort

Poulin, Robert

188

Direct and indirect costs of co-infection in the wild: Linking gastrointestinal parasite communities, host hematology, and immune function?  

PubMed Central

Most animals are concurrently infected with multiple parasites, and interactions among these parasites may influence both disease dynamics and host fitness. However, the sublethal costs of parasite infections are difficult to measure and the effects of concomitant infections with multiple parasite species on individual physiology and fitness are poorly described for wild hosts. To understand the direct and indirect physiological costs of co-infection, we investigated the relationships among gastrointestinal parasite richness, species identity, and abundance and host hematological parameters, body condition, and investment in lymphocyte defenses. Using aggregate-scale parasite data from African buffalo (Syncerus caffer), we found few direct or indirect associations between infection and hematology in male hosts, and no significant associations were observed in female hosts or with respect to body condition in either sex. These results suggest that only strong physiological effects are detectable with aggregate-scale parasite data, and that hematological variables may be more sensitive to changes in condition than standard body fat condition indices. Analyses accounting for parasite species identity in female buffalo revealed that different parasites show distinct relationships with host hematology, body condition, and immune investment. However, four of six species-specific associations were obscured when parasites were considered in combination. Overall, fitness-related physiological mediators such as hematological indices may provide assessments of direct and indirect effects of parasite infection, particularly when parasite species identity and community composition are considered. PMID:24533308

Budischak, Sarah A.; Jolles, Anna E.; Ezenwa, Vanessa O.

2012-01-01

189

Consistent Pattern of Local Adaptation during an Experimental Heat Wave in a Pipefish-Trematode Host-Parasite System  

PubMed Central

Extreme climate events such as heat waves are expected to increase in frequency under global change. As one indirect effect, they can alter magnitude and direction of species interactions, for example those between hosts and parasites. We simulated a summer heat wave to investigate how a changing environment affects the interaction between the broad-nosed pipefish (Syngnathus typhle) as a host and its digenean trematode parasite (Cryptocotyle lingua). In a fully reciprocal laboratory infection experiment, pipefish from three different coastal locations were exposed to sympatric and allopatric trematode cercariae. In order to examine whether an extreme climatic event disrupts patterns of locally adapted host-parasite combinations we measured the parasite's transmission success as well as the host's adaptive and innate immune defence under control and heat wave conditions. Independent of temperature, sympatric cercariae were always more successful than allopatric ones, indicating that parasites are locally adapted to their hosts. Hosts suffered from heat stress as suggested by fewer cells of the adaptive immune system (lymphocytes) compared to the same groups that were kept at 18C. However, the proportion of the innate immune cells (monocytes) was higher in the 18C water. Contrary to our expectations, no interaction between host immune defence, parasite infectivity and temperature stress were found, nor did the pattern of local adaptation change due to increased water temperature. Thus, in this host-parasite interaction, the sympatric parasite keeps ahead of the coevolutionary dynamics across sites, even under increasing temperatures as expected under marine global warming. PMID:22303448

Landis, Susanne H.; Kalbe, Martin; Reusch, Thorsten B. H.; Roth, Olivia

2012-01-01

190

Attachment of the parasitic weed dodder to the host.  

PubMed

The parasitic weed dodder (Cuscuta pentagona L.) invades a number of potential host species, but the mechanisms responsible for ensuring tight adhesion to the wide variety of host surfaces have yet to be identified. In this study, a battery of microscopy protocols is used to examine the host-parasite interface in an effort to deduce these mechanisms. As the dodder shoot approaches the host tissue, epidermal cells in the parasite shoot elongate and differentiate into secretory type trichomes. The trichome cell walls are malleable, allowing them to elongate towards the host and bend their walls to conform to the shape of the host cell surface. The presence of osmiophilic particles (probable cell-wall-loosening complexes) at far greater numbers than found in other species presages the expansion and malleable nature of the epidermal cells. In addition to the changes in cell shape, the dodder trichome cells secrete an electron-opaque cementing substance that covers the host-parasite interface. When probed with antibodies that recognize cell wall components, the cement reacted only with antibodies that recognize chiefly de-esterified pectins but not other common wall constituents. These data indicate that dodder utilizes both a cementing layer of pectin and a radically modified epidermal cell wall to secure the parasite to the perspective host. PMID:12099223

Vaughn, K C

2002-05-01

191

Differential Resistance among Host and Non-host Species Underlies the Variable Success of the Hemi-parasitic Plant Rhinanthus minor  

PubMed Central

Background and Aims Rhinanthus minor is a root hemiparasitic plant that attacks a wide range of host species which are severely damaged by the parasite. Rhinanthus minor also attempts unsuccessfully to form connections to a range of non-hosts which in contrast are not damaged by the parasite; however, the underlying physiological basis of these differences is not fully understood. Methods Biomass of hostparasite combinations was studied, and histology, electron microscopy and FT-IR microspectroscopy were used to determine the cellular-level interactions between Rhinanthus haustoria (the parasite's connective structure) and the roots of a range of potential host species. Results Two distinct defence responses were observed in the non-host forbs Plantago lanceolata and Leucanthemum vulgare. Firstly, L. vulgare was able to encapsulate the parasite's invading structures preventing it from gaining access to the stele. This was supported by FT-IR microspectroscopy, used to monitor lignification in response to Rhinanthus haustoria. Secondly, host cell fragmentation was observed at the interface between the parasite and P. lanceolata. Growth data confirmed the non-host status of the two forbs whilst, in contrast, grasses and a legume which were good hosts showed no evidence of defence at the host/parasite interface. Conclusions Variable resistance to Rhinanthus is shown for the first time to be controlled by cellular-level resistance to haustoria by either cell fragmentation or lignification at the host/parasite interface. PMID:17008350

CAMERON, DUNCAN D.; COATS, ALISON M.; SEEL, WENDY E.

2006-01-01

192

Brood parasites lay eggs matching the appearance of host clutches  

PubMed Central

Interspecific brood parasitism represents a prime example of the coevolutionary arms race where each party has evolved strategies in response to the other. Here, we investigated whether common cuckoos (Cuculus canorus) actively select nests within a host population to match the egg appearance of a particular host clutch. To achieve this goal, we quantified the degree of egg matching using the avian vision modelling approach. Randomization tests revealed that cuckoo eggs in naturally parasitized nests showed lower chromatic contrast to host eggs than those assigned randomly to other nests with egg-laying date similar to naturally parasitized clutches. Moreover, egg matching in terms of chromaticity was better in naturally parasitized nests than it would be in the nests of the nearest active non-parasitized neighbour. However, there was no indication of matching in achromatic spectral characteristics whatsoever. Thus, our results clearly indicate that cuckoos select certain host nests to increase matching of their own eggs with host clutches, but only in chromatic characteristics. Our results suggest that the ability of cuckoos to actively choose host nests based on the eggshell appearance imposes a strong selection pressure on host egg recognition. PMID:24258721

Honza, Marcel; ulc, Michal; Jelnek, Vclav; Pogayov, Milica; Prochzka, Petr

2014-01-01

193

Host-parasite interface of Veronica persica and Sorosphaera veronicae (Plasmodiophoromycetes)  

Microsoft Academic Search

The host-parasite interface between host, Veronica persica Poir., and parasite, Sorosphaera veronicae Schroeter, is observed to consist of a single, unit membrane, presumably the plasma membrane of the fungal parasite.

James P. Braselton; Charles E. Miller

1975-01-01

194

Parasite diversity and coinfection determine pathogen infection success and host fitness  

E-print Network

Parasite diversity and coinfection determine pathogen infection success and host fitness Pieter T continues to gain empirical support, the influence of natural variation in parasite diversity hosts representing 158 parasite assemblages with mechanistic experiments to evaluate the influ- ence

Johnson, Pieter

195

Individual patterns of habitat and nest-site use by hosts promote transgenerational transmission of avian brood parasitism status.  

PubMed

Brood parasitic birds impose variable fitness costs upon their hosts by causing the partial or complete loss of the hosts' own brood. Growing evidence from multiple avian host-parasite taxa indicates that exposure of individual hosts to parasitism is not necessarily random and varies with habitat use, nest-site selection, age or other phenotypic attributes. For instance, nonrandom patterns of brood parasitism had similar evolutionary consequences to those of limited horizontal transmission of parasites and pathogens across space and time and altered the dynamics of both population productivity and co-evolutionary interactions of hosts and parasites. We report that brood parasitism status of hosts of brown-headed cowbirds Molothrus ater is also transmitted across generations in individually colour-banded female prothonotary warblers Protonotaria citrea. Warbler daughters were more likely to share their mothers' parasitism status when showing natal philopatry at the scale of habitat patch. Females never bred in their natal nestboxes but daughters of parasitized mothers had shorter natal dispersal distances than daughters of nonparasitized mothers. Daughters of parasitized mothers were more likely to use nestboxes that had been parasitized by cowbirds in both the previous and current years. Although difficult to document in avian systems, different propensities of vertical transmission of parasitism status within host lineages will have critical implications both for the evolution of parasite tolerance in hosts and, if found to be mediated by lineages of parasites themselves, for the difference in virulence between such extremes as the nestmate-tolerant and nestmate-eliminator strategies of different avian brood parasite species. PMID:17922717

Hoover, Jeffrey P; Hauber, Mark E

2007-11-01

196

No evidence for specificity between host and parasite genotypes in experimental Strongyloides ratti (Nematoda) infections  

E-print Network

No evidence for specificity between host and parasite genotypes in experimental Strongyloides ratti host and parasite genotypes, i.e. the resistance of particular host genotypes to particular parasite genotypes and the infectivity of particular parasite genotypes for particular host genotypes. Determining

Paterson, Steve

197

Ectoparasitism and stress hormones: strategy of host exploitation, common host-parasite history and energetics matter.  

PubMed

Parasites are thought to have numerous negative effects on their hosts. These negative effects may be associated with stress in a host. We evaluated the effects of four species of flea ectoparasites (Parapulex chephrenis, Synosternus cleopatrae, Xenopsylla conformis and Xenopsylla ramesis) on non-specific responses of eight species of rodents (Meriones crassus, Gerbillus dasyurus, Gerbillus andersoni, Gerbillus pyramidum, Gerbillus nanus, Acomys cahirinus, Acomys russatus and Mesocricetus auratus) and measured faecal glucocorticoid metabolites concentrations (FGMC) produced by the hosts. We found no effect of body mass of an individual rodent on FGMCs. Parasitism by fleas with a 'stay on the host body' exploitation strategy was associated with higher host FGMCs than parasitism by fleas that spent most of their life 'off-host'. FGMCs among rodents infested by the same flea species were correlated positively with the phylogenetic distance of a given rodent from the principal host of this flea; changes in FGMCs were lower in the host species more closely related to the flea's principal host. Changes in FMGCs of a host while parasitized were correlated with a host's change in body mass, where hosts that lost more body mass had higher FGMCs. Our results suggest that ectoparasitism can be stressful to their hosts. However, the occurrence of parasite-induced stress seems to depend on the identity of both host and parasite species and the evolutionary history of a host-parasite association. To our knowledge, this is the first multispecies study to evaluate the effect of ectoparasites on glucocorticoid hormones in small mammals. PMID:24661039

St Juliana, Justin R; Khokhlova, Irina S; Wielebnowski, Nadja; Kotler, Burt P; Krasnov, Boris R

2014-03-24

198

Relative host body condition and food availability influence epidemic dynamics: a Poecilia reticulata-Gyrodactylus turnbulli host-parasite model.  

PubMed

Understanding disease transmission is important to species management and human health. Host body condition, nutrition and disease susceptibility interact in a complex manner, and while the individual effects of these variables are well known, our understanding of how they interact and translate to population dynamics is limited. Our objective was to determine whether host relative body condition influences epidemic dynamics, and how this relationship is affected by food availability. Poecilia reticulata (guppies) of roughly similar size were selected and assembled randomly into populations of 10 guppies assigned to 3 different food availability treatments, and the relative condition index (Kn) of each fish was calculated. We infected 1 individual per group ('source' fish) with Gyrodactyus turnbulli and counted parasites on each fish every other day for 10 days. Epidemic parameters for each population were analysed using generalized linear models. High host Kn-particularly that of the 'source' fish-exerted a positive effect on incidence, peak parasite burden, and the degree of parasite aggregation. Low food availability increased the strength of the associations with peak burden and aggregation. Our findings suggest that host Kn and food availability interact to influence epidemic dynamics, and that the condition of the individual that brings the parasite into the host population has a profound impact on the spread of infection. PMID:23122390

Tadiri, Christina P; Dargent, Felipe; Scott, Marilyn E

2013-03-01

199

Temperature stress and parasitism of endothermic hosts under climate change.  

PubMed

Climate change is a major threat to global environmental stability and is predicted to cause more frequent extreme weather events with higher levels of heat and cold stress. The physiological effects of such events on parasitic infections within endotherms are poorly studied and rarely considered in the context of climate change where an emphasis on ectothermic components of parasite life cycles (free-living stages and invertebrate hosts or vectors) predominates. However, thermal stress can affect parasite establishment, growth, fecundity, and development within endothermic hosts and may thus potentially influence transmission potential. Such changes can be caused by temperature effects on host physiological homeostasis, predominantly endocrine and immune systems, and may have wide implications for parasite epidemiology under extreme climatic events. PMID:24613288

Morley, Neil J; Lewis, John W

2014-05-01

200

The cellular immune response of Daphnia magna under host-parasite genetic variation and variation in initial dose.  

PubMed

In invertebrate-parasite systems, the likelihood of infection following parasite exposure is often dependent on the specific combination of host and parasite genotypes (termed genetic specificity). Genetic specificity can maintain diversity in host and parasite populations and is a major component of the Red Queen hypothesis. However, invertebrate immune systems are thought to only distinguish between broad classes of parasite. Using a natural host-parasite system with a well-established pattern of genetic specificity, the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa, we found that only hosts from susceptible host-parasite genetic combinations mounted a cellular response following exposure to the parasite. These data are compatible with the hypothesis that genetic specificity is attributable to barrier defenses at the site of infection (the gut), and that the systemic immune response is general, reporting the number of parasite spores entering the hemocoel. Further supporting this, we found that larger cellular responses occurred at higher initial parasite doses. By studying the natural infection route, where parasites must pass barrier defenses before interacting with systemic immune responses, these data shed light on which components of invertebrate defense underlie genetic specificity. PMID:23025616

Auld, Stuart K J R; Edel, Kai H; Little, Tom J

2012-10-01

201

The cellular immune response of Daphnia magna under host-parasite genetic variation and variation in initial dose  

PubMed Central

In invertebrate-parasite systems, the likelihood of infection following parasite exposure is often dependent on the specific combination of host and parasite genotypes (termed genetic specificity). Genetic specificity can maintain diversity in host and parasite populations and is a major component of the Red Queen hypothesis. However, invertebrate immune systems are thought to only distinguish between broad classes of parasite. Using a natural host-parasite system with a well-established pattern of genetic specificity, the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa, we found that only hosts from susceptible host-parasite genetic combinations mounted a cellular response following exposure to the parasite. These data are compatible with the hypothesis that genetic specificity is attributable to barrier defenses at the site of infection (the gut), and that the systemic immune response is general, reporting the number of parasite spores entering the hemocoel. Further supporting this, we found that larger cellular responses occurred at higher initial parasite doses. By studying the natural infection route, where parasites must pass barrier defenses before interacting with systemic immune responses, these data shed light on which components of invertebrate defense underlie genetic specificity. PMID:23025616

Auld, Stuart K. J. R; Edel, Kai H.; Little, Tom J.

2013-01-01

202

Differential responses to related hosts by nesting and non-nesting parasites in a brood-parasitic duck.  

PubMed

Host-parasite relatedness may facilitate the evolution of conspecific brood parasitism, but empirical support for this contention remains inconclusive. One reason for this disparity may relate to the diversity of parasitic tactics, a key distinguishing feature being whether the parasite has a nest of her own. Previous work suggests that parasites without nests of their own may be of inferior phenotypic quality, but because of difficulties in identifying these parasitic individuals, little is known about their host selection criteria. We used high-resolution molecular maternity tests to assign parasitic offspring to known parasites with and without their own nests in a population of Barrow's goldeneyes (Bucephala islandica). We determined whether parasite nesting status, host-parasite relatedness and distance between host and parasite nests affected the probability of parasitizing a host and the number of eggs laid per host. We also investigated whether nesting parasites, conventionally nesting females and non-nesting parasites differed regarding their age, structural size, body condition, nesting phenology or total brood size. The probability of engaging in parasitism increased with host-parasite relatedness and spatial proximity to host nests for nesting and non-nesting females alike. However, nesting parasites increased the number of eggs donated with relatedness to the host, while non-nesting parasites did not do so. Non-nesting parasites laid fewer eggs in total, but did not differ by any of the other quality measures from conventional nesters or nesting parasites. Our study provides the first demonstration that nesting and non-nesting parasites from the same population may use different host selection criteria. PMID:21923774

Jaatinen, Kim; st, Markus; Gienapp, Phillip; Meril, Juha

2011-12-01

203

Sex differences in host defence interfere with parasite-mediated selection for outcrossing during hostparasite coevolution  

PubMed Central

The Red Queen hypothesis proposes that coevolving parasites select for outcrossing in the host. Outcrossing relies on males, which often show lower immune investment due to, for example, sexual selection. Here, we demonstrate that such sex differences in immunity interfere with parasite-mediated selection for outcrossing. Two independent coevolution experiments with Caenorhabditis elegans and its microparasite Bacillus thuringiensis produced decreased yet stable frequencies of outcrossing male hosts. A subsequent systematic analysis verified that male C. elegans suffered from a direct selective disadvantage under parasite pressure (i.e. lower resistance, decreased sexual activity, increased escape behaviour), which can reduce outcrossing and thus male frequencies. At the same time, males offered an indirect selective benefit, because male-mediated outcrossing increased offspring resistance, thus favouring male persistence in the evolving populations. As sex differences in immunity are widespread, such interference of opposing selective constraints is likely of central importance during host adaptation to a coevolving parasite. PMID:23301667

Masri, Leila; Schulte, Rebecca D; Timmermeyer, Nadine; Thanisch, Stefanie; Crummenerl, Lena Luise; Jansen, Gunther; Michiels, Nico K; Schulenburg, Hinrich

2013-01-01

204

Higher resources decrease fluctuating selection during host-parasite coevolution.  

PubMed

We still know very little about how the environment influences coevolutionary dynamics. Here, we investigated both theoretically and empirically how nutrient availability affects the relative extent of escalation of resistance and infectivity (arms race dynamic; ARD) and fluctuating selection (fluctuating selection dynamic; FSD) in experimentally coevolving populations of bacteria and viruses. By comparing interactions between clones of bacteria and viruses both within- and between-time points, we show that increasing nutrient availability resulted in coevolution shifting from FSD, with fluctuations in average infectivity and resistance ranges over time, to ARD. Our model shows that range fluctuations with lower nutrient availability can be explained both by elevated costs of resistance (a direct effect of nutrient availability), and reduced benefits of resistance when population sizes of hosts and parasites are lower (an indirect effect). Nutrient availability can therefore predictably and generally affect qualitative coevolutionary dynamics by both direct and indirect (mediated through ecological feedbacks) effects on costs of resistance. PMID:25167763

Lopez Pascua, Laura; Hall, Alex R; Best, Alex; Morgan, Andrew D; Boots, Mike; Buckling, Angus

2014-11-01

205

Host Density and Competency Determine the Effects of Host Diversity on Trematode Parasite Infection  

PubMed Central

Variation in host species composition can dramatically alter parasite transmission in natural communities. Whether diverse host communities dilute or amplify parasite transmission is thought to depend critically on species traits, particularly on how hosts affect each others densities, and their relative competency as hosts. Here we studied a community of potential hosts and/or decoys (i.e. non-competent hosts) for two trematode parasite species, Echinostoma trivolvis and Ribeiroia ondatrae, which commonly infect wildlife across North America. We manipulated the density of a focal host (green frog tadpoles, Rana clamitans), in concert with manipulating the diversity of alternative species, to simulate communities where alternative species either (1) replace the focal host species so that the total number of individuals remains constant (substitution) or (2) add to total host density (addition). For E. trivolvis, we found that total parasite transmission remained roughly equal (or perhaps decreased slightly) when alternative species replaced focal host individuals, but parasite transmission was higher when alternative species were added to a community without replacing focal host individuals. Given the alternative species were roughly equal in competency, these results are consistent with current theory. Remarkably, both total tadpole and per-capita tadpole infection intensity by E. trivolvis increased with increasing intraspecific host density. For R. ondatrae, alternative species did not function as effective decoys or hosts for parasite infective stages, and the diversity and density treatments did not produce clear changes in parasite transmission, although high tank to tank variation in R. ondatrae infection could have obscured patterns. PMID:25119568

Wojdak, Jeremy M.; Edman, Robert M.; Wyderko, Jennie A.; Zemmer, Sally A.; Belden, Lisa K.

2014-01-01

206

Not to be suppressed? Rethinking the host response at a root-parasite interface.  

PubMed

Root-knot nematodes are highly efficient plant parasites that establish permanent feeding sites within host roots. The initiation of this feeding site is critical for parasitic success and requires an interaction with multiple signaling pathways involved in plant development and environmental response. Resistance against root-knot nematodes is relatively rare amongst their broad host range and they remain a major threat to agriculture. The development of effective and sustainable control strategies depends on understanding how host signaling pathways are manipulated during invasion of susceptible hosts. It is generally understood that root-knot nematodes either suppress host defense signaling during infestation or are able to avoid detection altogether, explaining their profound success as parasites. However, when compared to the depth of knowledge from other well-studied pathogen interactions, the published data on host responses to root-knot nematode infestation do not yet provide convincing support for this hypothesis and alternative explanations also exist. It is equally possible that defense-like signaling responses are actually induced and required during the early stages of root-knot nematode infestation. We describe how defense-signaling is highly context-dependent and that caution is necessary when interpreting transcriptional responses in the absence of appropriate control data or stringent validation of gene annotation. Further hypothesis-driven studies on host defense-like responses are required to account for these limitations and advance our understanding of root-knot nematode parasitism of plants. PMID:24157203

Goto, Derek B; Miyazawa, Hikota; Mar, Jessica C; Sato, Masanao

2013-12-01

207

A parasite reveals cryptic phylogeographic history of its host.  

PubMed Central

This study compares the continental phylogeographic patterns of two wild European species linked by a host-parasite relationship: the field mouse Apodemus sylvaticus and one of its specific parasites, the nematode Heligmosomoides polygyrus. A total of 740 base pairs (bp) of the mitochondrial cytochrome b (cyt b) gene were sequenced in 122 specimens of H. polygyrus and compared with 94 cyt b gene sequences (974 bp) previously acquired for A. sylvaticus. The results reveal partial spatial and temporal congruences in the differentiation of both species' lineages: the parasite and its host present three similar genetic and geographical lineages, i.e. Western European, Italian and Sicilian, and both species recolonized northwestern Europe from the Iberian refuge at the end of the Pleistocene. However, H. polygyrus presents three particular differentiation events. The relative rate of molecular evolution of the cyt b gene was estimated to be 1.5-fold higher in the parasite than in its host. Therefore, the use of H. polygyrus as a biological magnifying glass is discussed as this parasite may highlight previously undetected historical events of its host. The results show how incorporating phylogeographic information of an obligate associate can help to better understand the phylogeographic pattern of its host. PMID:15615681

Nieberding, C.; Morand, S.; Libois, R.; Michaux, J. R.

2004-01-01

208

Research paper Are cryptic host species also cryptic to parasites? Host specificity and geographical  

E-print Network

) or Acanthocephala (Kennedy, 2006). The existence of multiple host species can have important epidemiological Cryptic species Acanthocephala Amphipods A B S T R A C T Many parasites infect multiple host species. Gammarus pulex is a common host for multiple species of Acanthocephala in Europe but, in Switzerland

209

Correlated evolution between host immunity and parasite life histories in primates and oxyurid parasites.  

PubMed Central

Maturation time is a pivotal life-history trait of parasitic nematodes, determining adult body size, as well as daily and total fecundity. Recent theoretical work has emphasized the influence of prematurational mortality on the optimal values of age and size at maturity in nematodes. Eosinophils are a family of white blood cells often associated with infections by parasitic nematodes. Although the role of eosinophils in nematode resistance is controversial, recent work has suggested that the action of these immune effectors might be limited to the larval stages of the parasite. If eosinophils act on larval survival, one might predict, in line with theoretical models, that nematode species living in hosts with large eosinophil numbers should show reduced age and size at maturity. We tested this prediction using the association between the pinworms (Oxyuridae, Nematoda) and their primate hosts. Pinworms are highly host specific and are expected to be involved in a coevolutionary process with their hosts. We found that the body size of female parasites was negatively correlated with eosinophil concentration, whereas the concentration of two other leucocyte families-neutrophils and lymphocytes-was unrelated to female body size. Egg size of parasites also decreased with host eosinophil concentration, independently of female size. Male body size was unrelated to host immune parameters. Primates with the highest immune defence, therefore, harbour small female pinworms laying small eggs. These results are in agreement with theoretical expectations and suggest that life histories of oxyurid parasites covary with the immune defence of their hosts. Our findings illustrate the potential for host immune defence as a factor driving parasite life-history evolution. PMID:14667339

Sorci, Gabriele; Skarstein, Frode; Morand, Serge; Hugot, Jean-Pierre

2003-01-01

210

Parasites in Hosts with Special Life Histories  

Microsoft Academic Search

One-hundred and forty seven specimens of the Cuckoo Cuculus canorus, 356 individuals of the Crossbill Loxia curvirostra and 79 specimens of the Swift Apus apus were captured on the Curonian Spit in the Baltic Sea and investigated for haematozoa by microscopic examination of stained blood smears. Haemosporidian parasites (Sporozoa, Haemosporida) were not recorded in the Cuckoo and the Swift. However,

Gediminas Valki?nas; Tatjana Aleksandrovna Iezhova

2001-01-01

211

Associations between host migration and the prevalence of a protozoan parasite in natural  

E-print Network

Associations between host migration and the prevalence of a protozoan parasite in natural, this host±parasite system provides the opportunity to examine how variation in parasite prevalence relates to host movement patterns. 2. Parasite prevalence was evaluated using 14 790 adult monarchs captured

212

Spatio-temporal dynamics of bumblebee nest parasites (Bombus subgenus Psythirus ssp.) and their hosts  

E-print Network

Spatio-temporal dynamics of bumblebee nest parasites (Bombus subgenus Psythirus ssp in the British Isles. 2. A model of nest parasitism predicted host threshold densities and stable deterministic, parasite-free zones were evident in areas of low host abundance, but the host thresh- old for parasite

Antonovics, Janis

213

COPEPODS AND SCOMBRID FISHES: A STUDY IN HOST-PARASITE RELATIONSHIPS  

E-print Network

COPEPODS AND SCOMBRID FISHES: A STUDY IN HOST-PARASITE RELATIONSHIPS ROGER F. CRESSEY,I BRUCE B. COLLE'ITE,' AND JOSEPH L. Russo' ABSTRACT Host specificity ofthe copepods parasitic on scombrid fishes is the basis for an analysis ofthe host-parasite relationship. A total of 46 different species of parasitic

214

Beyond immunity: quantifying the effects of host anti-parasite behavior on parasite transmission.  

PubMed

A host's first line of defense in response to the threat of parasitic infection is behavior, yet the efficacy of anti-parasite behaviors in reducing infection are rarely quantified relative to immunological defense mechanisms. Larval amphibians developing in aquatic habitats are at risk of infection from a diverse assemblage of pathogens, some of which cause substantial morbidity and mortality, suggesting that behavioral avoidance and resistance could be significant defensive strategies. To quantify the importance of anti-parasite behaviors in reducing infection, we exposed larval Pacific chorus frogs (Pseudacris regilla) to pathogenic trematodes (Ribeiroia and Echinostoma) in one of two experimental conditions: behaviorally active (unmanipulated) or behaviorally impaired (anesthetized). By quantifying both the number of successful and unsuccessful parasites, we show that host behavior reduces infection prevalence and intensity for both parasites. Anesthetized hosts were 20-39% more likely to become infected and, when infected, supported 2.8-fold more parasitic cysts. Echinostoma had a 60% lower infection success relative to the more deadly Ribeiroia and was also more vulnerable to behaviorally mediated reductions in transmission. For Ribeiroia, increases in host mass enhanced infection success, consistent with epidemiological theory, but this relationship was eroded among active hosts. Our results underscore the importance of host behavior in mitigating disease risk and suggest that, in some systems, anti-parasite behaviors can be as or more effective than immune-mediated defenses in reducing infection. Considering the severe pathologies induced by these and other pathogens of amphibians, we emphasize the value of a broader understanding of anti-parasite behaviors and how co-occurring stressors affect them. PMID:20857146

Daly, Elizabeth W; Johnson, Pieter T J

2011-04-01

215

The evolution of parasites from their hosts: intra- and interspecific parasitism and Emery's rule.  

PubMed Central

In some taxa of Hymenoptera, fungi, red algae and mistletoe, parasites and their hosts are either sibling species or at least closely related (Emery's rule). Three evolutionary mechanisms have been proposed for this phenomenon: (i) intraspecific parasitism is followed by sympatric speciation; (ii) allopatric speciation is followed by secondary sympatry and the subsequent parasitism of one sibling species by the other; and (iii) allopatric speciation of a species with intraspecific parasitism is followed by secondary sympatry, in which one species becomes an obligate parasite of the other. Mechanisms (i) and (ii) are problematic, while mechanism (iii) has not, to our knowledge, been analysed quantitatively. In this paper, we develop a model for single- and two-species evolutionary stable strategies (ESSs) to examine the basis for Emery's rule and to determine whether mechanism (iii) is consistent with ESS reasoning. In secondary sympatry after allopatric speciation, the system's evolution depends on the relative abundances of the two sibling species and on the proportional damage wrought by parasites of each species on non-parasitic members of the other. Depending on these interspecific effects, either the rarer or the commoner species may become the parasite and the levels of within-species parasitism need not determine which evolves to obligate parasitism. PMID:12065048

Lowe, Roger M; Ward, Seamus A; Crozier, Ross H

2002-01-01

216

Nematode-coccidia parasite co-infections in African buffalo: Epidemiology and associations with host condition and pregnancy.  

PubMed

Co-infections are common in natural populations and interactions among co-infecting parasites can significantly alter the transmission and host fitness costs of infection. Because both exposure and susceptibility vary over time, predicting the consequences of parasite interactions on host fitness and disease dynamics may require detailed information on their effects across different environmental (season) and host demographic (age, sex) conditions. This study examines five years of seasonal health and co-infection patterns in African buffalo (Syncerus caffer). We use data on two groups of gastrointestinal parasites, coccidia and nematodes, to test the hypothesis that co-infection and season interact to influence (1) parasite prevalence and intensity and (2) three proxies for host fitness: host pregnancy, host body condition, and parasite aggregation. Our results suggest that season-dependent interactions between nematodes and coccidia affect the distribution of infections. Coccidia prevalence, coccidia intensity and nematode prevalence were sensitive to factors that influence host immunity and exposure (age, sex, and season) but nematode intensity was most strongly predicted by co-infection with coccidia and its interaction with season. The influence of co-infection on host body condition and parasite aggregation occurred in season-dependent manner. Co-infected buffalo in the early wet season were in worse condition, had a less aggregated distribution of nematode parasites, and lower nematode infection intensity than buffalo infected with nematodes alone. We did not detect an effect of infection or co-infection on host pregnancy. These results suggest that demographic and seasonal variation may mediate the effects of parasites, and their interactions, on the distribution and fitness costs of infection. PMID:25161911

Gorsich, Erin E; Ezenwa, Vanessa O; Jolles, Anna E

2014-08-01

217

Available online at www.sciencedirect.com Parasitism proteins in nematodeplant interactions  

E-print Network

that can localize to the plant cell nucleus, potential suppressors of host defense, mimics of plantAvailable online at www.sciencedirect.com Parasitism proteins in nematode­plant interactions Eric L parasitism proteins secreted by nematodes to modify plant tissues for parasitism includes cell

Hussey, Richard S.

218

Plant parasitic nematode effectors target host defense and nuclear functions to establish feeding cells  

PubMed Central

Plant parasitic nematodes are microscopic worms, the most damaging species of which have adopted a sedentary lifestyle within their hosts. These obligate endoparasites have a biotrophic relationship with plants, in which they induce the differentiation of root cells into hypertrophied, multinucleate feeding cells (FCs). Effectors synthesized in the esophageal glands of the nematode are injected into the plant cells via the syringe-like stylet and play a key role in manipulating the host machinery. The establishment of specialized FCs requires these effectors to modulate many aspects of plant cell morphogenesis and physiology, including defense responses. This cell reprogramming requires changes to host nuclear processes. Some proteins encoded by parasitism genes target host nuclei. Several of these proteins were immunolocalized within FC nuclei or shown to interact with host nuclear proteins. Comparative genomics and functional analyses are gradually revealing the roles of nematode effectors. We describe here these effectors and their hypothesized roles in the unique feeding behavior of these pests. PMID:23493679

Quentin, Michael; Abad, Pierre; Favery, Bruno

2013-01-01

219

Host physiological condition regulates parasitic plant performance: Arceuthobium vaginatum subsp. cryptopodum on Pinus ponderosa  

Microsoft Academic Search

Much research has focused on effects of plant parasites on host-plant physiology and growth, but little is known about effects of host physiological condition on parasite growth. Using the parasitic dwarf mistletoe Arceuthobium vaginatum subsp. cryptopodum (Viscaceae) and its host Pinus ponderosa, we investigated whether changes in host physiological condition influenced mistletoe shoot development in northern Arizona forests. We conducted

Christopher P. Bickford; Thomas E. Kolb; Brian W. Geils

2005-01-01

220

Host-parasite population dynamics under combined frequency-and density-dependent transmission  

E-print Network

Host-parasite population dynamics under combined frequency- and density-dependent transmission, Scotland, EH14 4AS. Many host-parasite models assume that transmission increases linearly with host alternative (usually applied to sexually transmitted parasites) assumes instead that the rate at which hosts

White, Andrew

221

Volatile chemical cues guide host location and host selection by parasitic plants.  

PubMed

The importance of plant volatiles in mediating interactions between plant species is much debated. Here, we demonstrate that the parasitic plant Cuscuta pentagona (dodder) uses volatile cues for host location. Cuscuta pentagona seedlings exhibit directed growth toward nearby tomato plants (Lycopersicon esculentum) and toward extracted tomato-plant volatiles presented in the absence of other cues. Impatiens (Impatiens wallerana) and wheat plants (Triticum aestivum) also elicit directed growth. Moreover, seedlings can distinguish tomato and wheat volatiles and preferentially grow toward the former. Several individual compounds from tomato and wheat elicit directed growth by C. pentagona, whereas one compound from wheat is repellent. These findings provide compelling evidence that volatiles mediate important ecological interactions among plant species. PMID:17008532

Runyon, Justin B; Mescher, Mark C; De Moraes, Consuelo M

2006-09-29

222

Cowbird removals unexpectedly increase productivity of a brood parasite and the songbird host.  

PubMed

Generalist brood parasites reduce productivity and population growth of avian hosts and have been implicated in population declines of several songbirds of conservation concern. To estimate the demographic effects of brood parasitism on Bell's Vireos (Vireo bellii), we removed Brown-headed Cowbirds (Molothrus ater) in a replicated switchback experimental design. Cowbird removals decreased parasitism frequency from 77% and 85% at unmanipulated plots to 58% and 47% at removal plots in 2004 and 2005, respectively. Vireo productivity per pair was higher at cowbird removal plots when years were pooled (mean = 2.6 +/- 0.2 [SE] young per pair) compared to unmanipulated plots (1.2 +/- 0.1). Nest desertion frequency was lower at cowbird removal plots (35% of parasitized nests) compared to unmanipulated plots (69%) because removal of host eggs was the proximate cue for nest desertion, and vireos experienced lower rates of egg loss at cowbird removal plots. Nest success was higher among unparasitized than parasitized nests, and parasitized nests at cowbird removal plots had a higher probability of success than parasitized nests at unmanipulated plots. Unexpectedly, cowbird productivity from vireo pairs was higher at cowbird removal plots (mean = 0.3 +/- 0.06 young per pair) than at unmanipulated plots (0.1 +/- 0.03) because fewer parasitized nests were deserted and the probability of nest success was higher. Our study provides the first evidence that increases in cowbird productivity may be an unintended consequence of cowbird control programs, especially during the initial years of trapping when parasitism may only be moderately reduced. Thus, understanding the demographic impacts of cowbird removals requires an informed understanding of the behavioral ecology of host-parasite interactions. PMID:18488614

Kosciuch, Karl L; Sandercock, Brett K

2008-03-01

223

Nocardia species: host-parasite relationships.  

PubMed Central

The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia asteroides, and N. brasiliensis, N. farcinica, N. otitidiscaviarum, N. nova, and N. transvalensis cause a variety of diseases in both normal and immunocompromised humans and animals. The mechanisms of pathogenesis are complex, not fully understood, and include the capacity to evade or neutralize the myriad microbicidal activities of the host. The relative virulence of N. asteroides correlates with the ability to inhibit phagosome-lysosome fusion in phagocytes; to neutralize phagosomal acidification; to detoxify the microbicidal products of oxidative metabolism; to modify phagocyte function; to grow within phagocytic cells; and to attach to, penetrate, and grow within host cells. Both activated macrophages and immunologically specific T lymphocytes constitute the major mechanisms for host resistance to nocardial infection, whereas B lymphocytes and humoral immunity do not appear to be as important in protecting the host. Thus, the nocardiae are facultative intracellular pathogens that can persist within the host, probably in a cryptic form (L-form), for life. Silent invasion of brain cells by some Nocardia strains can induce neurodegeneration in experimental animals; however, the role of nocardiae in neurodegenerative diseases in humans needs to be investigated. Images PMID:8055469

Beaman, B L; Beaman, L

1994-01-01

224

Malaria Parasite Development in the Mosquito and Infection of the Mammalian Host  

PubMed Central

Plasmodium sporozoites are the product of a complex developmental process in the mosquito vector and are destined to infect the mammalian liver. Attention has been drawn to the mosquito stages and preerythrocytic stages owing to recognition that these are bottlenecks in the parasite life cycle and that intervention at these stages can block transmission and prevent infection. Parasite progression in the Anopheles mosquito, sporozoite transmission to the mammalian host by mosquito bite, and subsequent infection of the liver are characterized by extensive migration of invasive stages, cell invasion, and developmental changes. Preparation for the liver phase in the mammalian host begins in the mosquito with an extensive reprogramming of the sporozoite to support efficient infection and survival. Here, we discuss what is known about the molecular and cellular basis of the developmental progression of parasites and their interactions with host tissues in the mosquito and during the early phase of mammalian infection. PMID:19575563

Aly, Ahmed S.I.; Vaughan, Ashley M.; Kappe, Stefan H.I.

2010-01-01

225

Begging Behaviour and Host Exploitation in Parasitic Cowbirds  

Microsoft Academic Search

In this chapter we explore the begging behaviour of cowbirds, obligate brood parasites that are typically raised in mixed\\u000a broods with host young. As strangers in the nest, cowbird nestlings present both challenges and opportunities to evolutionary\\u000a biologists. After a brief overview, we delve into four main topics: (1) the means by which cowbird young achieve success in\\u000a host nests;

Donald C. Dearborn; Gabriela Lichtenstein

226

Population mixing promotes arms race hostparasite coevolution  

PubMed Central

The consequences of hostparasite coevolution are highly contingent on the qualitative coevolutionary dynamics: whether selection fluctuates (fluctuating selection dynamic; FSD), or is directional towards increasing infectivity/resistance (arms race dynamic; ARD). Both genetics and ecology can play an important role in determining whether coevolution follows FSD or ARD, but the ecological conditions under which FSD shifts to ARD, and vice versa, are not well understood. The degree of population mixing is thought to increase host exposure to parasites, hence selecting for greater resistance and infectivity ranges, and we hypothesize this promotes ARD. We tested this by coevolving bacteria and viruses in soil microcosms and found that population mixing shifted bacteriavirus coevolution from FSD to ARD. A simple theoretical model produced qualitatively similar results, showing that mechanisms that increase host exposure to parasites tend to push dynamics towards ARD. The shift from FSD to ARD with increased population mixing may help to explain variation in coevolutionary dynamics between different hostparasite systems, and more specifically the observed discrepancies between laboratory and field bacteriavirus coevolutionary studies. PMID:25429018

Gmez, Pedro; Ashby, Ben; Buckling, Angus

2015-01-01

227

Population mixing promotes arms race host-parasite coevolution.  

PubMed

The consequences of host-parasite coevolution are highly contingent on the qualitative coevolutionary dynamics: whether selection fluctuates (fluctuating selection dynamic; FSD), or is directional towards increasing infectivity/resistance (arms race dynamic; ARD). Both genetics and ecology can play an important role in determining whether coevolution follows FSD or ARD, but the ecological conditions under which FSD shifts to ARD, and vice versa, are not well understood. The degree of population mixing is thought to increase host exposure to parasites, hence selecting for greater resistance and infectivity ranges, and we hypothesize this promotes ARD. We tested this by coevolving bacteria and viruses in soil microcosms and found that population mixing shifted bacteria-virus coevolution from FSD to ARD. A simple theoretical model produced qualitatively similar results, showing that mechanisms that increase host exposure to parasites tend to push dynamics towards ARD. The shift from FSD to ARD with increased population mixing may help to explain variation in coevolutionary dynamics between different host-parasite systems, and more specifically the observed discrepancies between laboratory and field bacteria-virus coevolutionary studies. PMID:25429018

Gmez, Pedro; Ashby, Ben; Buckling, Angus

2015-01-01

228

PATERNITY-PARASITISM TRADE-OFFS: A MODEL AND TEST OF HOST-PARASITE COOPERATION IN AN AVIAN CONSPECIFIC BROOD PARASITE  

Microsoft Academic Search

Abstract. Efforts to evaluate the evolutionary and ecological dynamics,of conspecific,brood parasitism in birds and other animals have focused on the fitness costs of parasitism to hosts and fitness benefits to parasites. However, it has been speculated recently that, in species with biparental care, host males might cooperate with parasitic females by allowing,access to the host nest in exchange,for copulations. We

Bruce E. Lyon; Wesley M. Hochachka; John M. Eadie

2002-01-01

229

Histopathology in hosts parasitized by Sarcoptes scabiei.  

PubMed

Histopathologic evaluation of nondermal tissue in rabbits infested with Sarcoptes scabiei var. canis was investigated. Severe infestation resulted in deviant serological and serum biochemical values. Histological study revealed structural changes in the tissues of specific organs. The most prominent histological finding was amyloidosis in the liver, glomerulus of the kidney, red pulp of the spleen, intestines, and tongue. Hosts treated for infestation exhibited no abnormal organ histology. PMID:2254824

Arlian, L G; Bruner, R H; Stuhlman, R A; Ahmed, M; Vyszenski-Moher, D L

1990-12-01

230

Paternity-parasitism trade-offs: a model and test of host-parasite cooperation in an avian conspecific brood parasite.  

PubMed

Efforts to evaluate the evolutionary and ecological dynamics of conspecific brood parasitism in birds and other animals have focused on the fitness costs of parasitism to hosts and fitness benefits to parasites. However, it has been speculated recently that, in species with biparental care, host males might cooperate with parasitic females by allowing access to the host nest in exchange for copulations. We develop a cost-benefit model to explore the conditions under which such host-parasite cooperation might occur. When the brood parasite does not have a nest of her own, the only benefit to the host male is siring some of the parasitic eggs (quasi-parasitism). Cooperation with the parasite is favored when the ratio of host male paternity of his own eggs relative to his paternity of parasitic eggs exceeds the cost of parasitism. When the brood parasite has a nest of her own, a host male can gain additional, potentially more important benefits by siring the high-value, low-cost eggs laid by the parasite in her own nest. Under these conditions, host males should be even more likely to accept parasitic eggs in return for copulations with the parasitic female. We tested these predictions for American coots (Fulica americana), a species with a high frequency of conspecific brood parasitism. Multilocus DNA profiling indicated that host males did not sire any of the parasitic eggs laid in host nests, nor did they sire eggs laid by the parasite in her own nest. We used field estimates of the model parameters from a four-year study of coots to predict the minimum levels of paternity required for the costs of parasitism to be offset by the benefits of mating with brood parasites. Observed levels of paternity were significantly lower than those predicted under a variety of assumptions, and we reject the hypothesis that host males cooperated with parasitic females. Our model clarifies the specific costs and benefits that influence host-parasite cooperation and, more generally, yields precise predictions about expected levels of host male paternity. These predictions will enable a more rigorous assessment of field studies designed to test adaptive hypotheses of host-parasite cooperation. PMID:12144024

Lyon, Bruce E; Hochachka, Wesley M; Eadie, John M

2002-06-01

231

Modulation of the Host Cell Proteome by the Intracellular Apicomplexan Parasite Toxoplasma gondii?  

PubMed Central

To investigate how intracellular parasites manipulate their host cell environment at the molecular level, we undertook a quantitative proteomic study of cells following infection with the apicomplexan parasite Toxoplasma gondii. Using conventional two-dimensional electrophoresis, difference gel electrophoresis (DIGE), and mass spectrometry, we identified host proteins that were consistently modulated in expression following infection. We detected modification of protein expression in key metabolic pathways, including glycolysis, lipid and sterol metabolism, mitosis, apoptosis, and structural-protein expression, suggestive of global reprogramming of cell metabolism by the parasite. Many of the differentially expressed proteins had not been previously implicated in the response to the parasite, while others provide important corroborative protein evidence for previously proposed hypotheses of pathogen-cell interactions. Significantly, over one-third of all modulated proteins were mitochondrial, and this was further investigated by DIGE analysis of a mitochondrion-enriched preparation from infected cells. Comparison of our proteomic data with previous transcriptional studies suggested that a complex relationship exits between transcription and protein expression that may be partly explained by posttranslational modifications of proteins and revealed the importance of investigating protein changes when interpreting transcriptional data. To investigate this further, we used phosphatase treatment and DIGE to demonstrate changes in the phosphorylation states of several key proteins following infection. Overall, our findings indicate that the host cell proteome responds in a dramatic way to T. gondii invasion, in terms of both protein expression changes and protein modifications, and reveal a complex and intimate molecular relationship between host and parasite. PMID:17967855

Nelson, M. M.; Jones, A. R.; Carmen, J. C.; Sinai, A. P.; Burchmore, R.; Wastling, J. M.

2008-01-01

232

Do parasitic trematode cercariae demonstrate a preference for susceptible host species?  

PubMed

Many parasites are motile and exhibit behavioural preferences for certain host species. Because hosts can vary in their susceptibility to infections, parasites might benefit from preferentially detecting and infecting the most susceptible host, but this mechanistic hypothesis for host-choice has rarely been tested. We evaluated whether cercariae (larval trematode parasites) prefer the most susceptible host species by simultaneously presenting cercariae with four species of tadpole hosts. Cercariae consistently preferred hosts in the following order: Anaxyrus (?=?Bufo) terrestris (southern toad), Hyla squirella (squirrel tree frog), Lithobates (?=?Rana) sphenocephala (southern leopard frog), and Osteopilus septentrionalis (Cuban tree frog). These host species varied in susceptibility to cercariae in an order similar to their attractiveness with a correlation that approached significance. Host attractiveness to parasites also varied consistently and significantly among individuals within a host species. If heritable, this individual-level host variation would represent the raw material upon which selection could act, which could promote a Red Queen "arms race" between host cues and parasite detection of those cues. If, in general, motile parasites prefer to infect the most susceptible host species, this phenomenon could explain aggregated distributions of parasites among hosts and contribute to parasite transmission rates and the evolution of virulence. Parasite preferences for hosts belie the common assumption of disease models that parasites seek and infect hosts at random. PMID:23272084

Sears, Brittany F; Schlunk, Andrea D; Rohr, Jason R

2012-01-01

233

Parasite-induced trophic facilitation exploited by a non-host predator: a manipulator's nightmare  

Microsoft Academic Search

Parasites with complex life cycles, relying on trophic transmission to a definitive host, very often induce changes in the behaviour or appearance of their intermediate hosts. Because this usually makes the intermediate host vulnerable to predation by the definitive host, it is generally assumed that the parasite's transmission rate is increased, and that the modification of the host is, therefore,

Kim N. Mouritsen; Robert Poulin

2003-01-01

234

Parasitism-induced Effects on Host Growth and Metabolic Efficiency in Tobacco Hornworm Larvae Parasitized by Cotesia congregata  

Microsoft Academic Search

Parasitism by the braconid wasp Cotesia congregata affects the growth of Manduca sexta larvae in a parasitoid dose-dependent fashion. Following parasitization of fourth-instar larvae, more heavily parasitized larvae grew larger compared to those containing fewer parasitoids due to an increase in host dry weight. The differences in host mass appeared to arise after oviposition. A dose-dependent enhancement of host dry

MARIANNE ALLEYNE; NANCY E BECKAGE

1997-01-01

235

Spatially and temporally structured avian brood parasitism affects the fitness benefits of hosts' rejection strategies  

Microsoft Academic Search

Avian brood parasitism reduces the success of parasitized broods, yet most hosts of brown-headed cow- birds, Molothrus ater, neither desert parasitized clutches nor eject parasite eggs. We investigated whether spatial and temporal patterns of repeated cowbird parasitism on individuals influence the benefits of desertion or ejection in prothonotary warblers, Protonotaria citrea, and red-winged blackbirds, Agelaius phoe- niceus. First, we demonstrated

Jeffrey P. Hoover; Ken Yasukawa; Mark E. Hauber

2006-01-01

236

Hostparasite relatedness shown by protein fingerprinting in a brood parasitic bird  

PubMed Central

Brood parasitism as an alternative female breeding tactic is particularly common in ducks, where hosts often receive eggs laid by parasitic females of the same species and raise their offspring. Herein, we test several aspects of a kin selection explanation for this phenomenon in goldeneye ducks (Bucephala clangula) by using techniques of egg albumen sampling and statistical bandsharing analysis based on resampling. We find that host and primary parasite are indeed often related, with mean r = 0.13, about as high as between first cousins. Relatedness to the host is higher in nests where a parasite lays several eggs than in those where she lays only one. Returning young females parasitize their birth nestmates (social mothers or sisters, which are usually also their genetic mothers and sisters) more often than expected by chance. Such adult relatives are also observed together in the field more often than expected and for longer periods than other females. Relatedness and kin discrimination, which can be achieved by recognition of birth nestmates, therefore play a role in these tactics and probably influence their success. PMID:11050150

Andersson, Malte; ?hlund, Matti

2000-01-01

237

Effects of parasites on host energy expenditure: the resting metabolic rate stalemate  

E-print Network

Effects of parasites on host energy expenditure: the resting metabolic rate stalemate Nicholas Robar, Dennis L. Murray, and Gary Burness Abstract: Detrimental effects of parasitism on host fitness are frequently attributed to parasite-associated perturbations to host energy budgets. It has therefore been

238

Comparative evolutionary genetics of trematode parasites (Plagiorchiidae) and their anuran hosts  

E-print Network

Comparative evolutionary genetics of trematode parasites (Plagiorchiidae) and their anuran hosts B of trematode parasites (Plagiorchiidae) and their anuran hosts. Can. J. Zool. 70: 993-1000. A study of five observed among trematodes with those of their respectivehosts suggeststhat host and parasite genetic

239

Parasite species richness in carnivores: effects of host body mass, latitude, geographical range and population density  

Microsoft Academic Search

Aim Comparative studies have revealed strong links between ecological factors and the number of parasite species harboured by different hosts, but studies of different taxonomic host groups have produced inconsistent results. As a step towards under- standing the general patterns of parasite species richness, we present results from a new comprehensive data base of over 7000 host-parasite combinations representing 146

Patrik Lindenfors; Charles L. Nunn; Kate E. Jones; Andrew A. Cunningham; Wes Sechrest; John L. Gittleman

2007-01-01

240

RESEARCH ARTICLE Open Access The effect of host social system on parasite  

E-print Network

RESEARCH ARTICLE Open Access The effect of host social system on parasite population genetic structure of a parasite, and consequently its ability to adapt to a given host, is strongly linked to its own life history as well as the life history of its host. While the effects of parasite life history

Alvarez, Nadir

241

A Large Repertoire of Parasite Epitopes Matched by a Large Repertoire of Host Immune Receptors in an Invertebrate Host/Parasite Model  

PubMed Central

For many decades, invertebrate immunity was believed to be non-adaptive, poorly specific, relying exclusively on sometimes multiple but germ-line encoded innate receptors and effectors. But recent studies performed in different invertebrate species have shaken this paradigm by providing evidence for various types of somatic adaptations at the level of putative immune receptors leading to an enlarged repertoire of recognition molecules. Fibrinogen Related Proteins (FREPs) from the mollusc Biomphalaria glabrata are an example of these putative immune receptors. They are known to be involved in reactions against trematode parasites. Following not yet well understood somatic mechanisms, the FREP repertoire varies considerably from one snail to another, showing a trend towards an individualization of the putative immune repertoire almost comparable to that described from vertebrate adaptive immune system. Nevertheless, their antigenic targets remain unknown. In this study, we show that a specific set of these highly variable FREPs from B. glabrata forms complexes with similarly highly polymorphic and individually variable mucin molecules from its specific trematode parasite S. mansoni (Schistosoma mansoni Polymorphic Mucins: SmPoMucs). This is the first evidence of the interaction between diversified immune receptors and antigenic variant in an invertebrate host/pathogen model. The same order of magnitude in the diversity of the parasite epitopes and the one of the FREP suggests co-evolutionary dynamics between host and parasite regarding this set of determinants that could explain population features like the compatibility polymorphism observed in B. glabrata/S. mansoni interaction. In addition, we identified a third partner associated with the FREPs/SmPoMucs in the immune complex: a Thioester containing Protein (TEP) belonging to a molecular category that plays a role in phagocytosis or encapsulation following recognition. The presence of this last partner in this immune complex argues in favor of the involvement of the formed complex in parasite recognition and elimination from the host. PMID:20838648

Mon, Yves; Gourbal, Benjamin; Duval, David; Du Pasquier, Louis; Kieffer-Jaquinod, Sylvie; Mitta, Guillaume

2010-01-01

242

A large repertoire of parasite epitopes matched by a large repertoire of host immune receptors in an invertebrate host/parasite model.  

PubMed

For many decades, invertebrate immunity was believed to be non-adaptive, poorly specific, relying exclusively on sometimes multiple but germ-line encoded innate receptors and effectors. But recent studies performed in different invertebrate species have shaken this paradigm by providing evidence for various types of somatic adaptations at the level of putative immune receptors leading to an enlarged repertoire of recognition molecules. Fibrinogen Related Proteins (FREPs) from the mollusc Biomphalaria glabrata are an example of these putative immune receptors. They are known to be involved in reactions against trematode parasites. Following not yet well understood somatic mechanisms, the FREP repertoire varies considerably from one snail to another, showing a trend towards an individualization of the putative immune repertoire almost comparable to that described from vertebrate adaptive immune system. Nevertheless, their antigenic targets remain unknown. In this study, we show that a specific set of these highly variable FREPs from B. glabrata forms complexes with similarly highly polymorphic and individually variable mucin molecules from its specific trematode parasite S. mansoni (Schistosoma mansoni Polymorphic Mucins: SmPoMucs). This is the first evidence of the interaction between diversified immune receptors and antigenic variant in an invertebrate host/pathogen model. The same order of magnitude in the diversity of the parasite epitopes and the one of the FREP suggests co-evolutionary dynamics between host and parasite regarding this set of determinants that could explain population features like the compatibility polymorphism observed in B. glabrata/S. mansoni interaction. In addition, we identified a third partner associated with the FREPs/SmPoMucs in the immune complex: a Thioester containing Protein (TEP) belonging to a molecular category that plays a role in phagocytosis or encapsulation following recognition. The presence of this last partner in this immune complex argues in favor of the involvement of the formed complex in parasite recognition and elimination from the host. PMID:20838648

Mon, Yves; Gourbal, Benjamin; Duval, David; Du Pasquier, Louis; Kieffer-Jaquinod, Sylvie; Mitta, Guillaume

2010-01-01

243

Host-parasite determinants of parasite population structure: lessons from bats and mites on the importance of time.  

PubMed

By definition, parasitic organisms are strongly dependant on their hosts, and for a great majority, this dependence includes host-to-host transmission. Constraints imposed by the host's spatial distribution and demography, in combination with those of the parasite, can lead to a metapopulation structure, where parasite populations are highly stochastic (i.e. prone to frequent extinctions and re-colonizations) and where drift becomes a major force shaping standing genetic variation. This, in turn, will directly affect the observed population structure, along with the ability of the parasite to adapt (or co-adapt) to its host. However, only a specific consideration of temporal dynamics can reveal the extent to which drift shapes parasite population structure; this is rarely taken into account in population genetic studies of parasitic organisms. The study by Bruyndonckx et al. in this issue of Molecular Ecology does just this and, in doing so, illustrates how a comparison of host-parasite co-structures in light of temporal dynamics can be particularly informative for understanding the ecological and evolutionary constraints imposed by the host. More specifically, the authors examine spatial and temporal population genetic data of a parasitic mite Spinturnix bechsteini that exclusively exploits the Bechstein's bat Myotis bechsteinii and consider these data in relation to host-parasite life histories and the population structure of the host. PMID:19703249

McCoy, Karen D

2009-09-01

244

Antagonistic experimental coevolution with a parasite increases host recombination frequency  

PubMed Central

Background One of the big remaining challenges in evolutionary biology is to understand the evolution and maintenance of meiotic recombination. As recombination breaks down successful genotypes, it should be selected for only under very limited conditions. Yet, recombination is very common and phylogenetically widespread. The Red Queen Hypothesis is one of the most prominent hypotheses for the adaptive value of recombination and sexual reproduction. The Red Queen Hypothesis predicts an advantage of recombination for hosts that are coevolving with their parasites. We tested predictions of the hypothesis with experimental coevolution using the red flour beetle, Tribolium castaneum, and its microsporidian parasite, Nosema whitei. Results By measuring recombination directly in the individuals under selection, we found that recombination in the host population was increased after 11 generations of coevolution. Detailed insights into genotypic and phenotypic changes occurring during the coevolution experiment furthermore helped us to reconstruct the coevolutionary dynamics that were associated with this increase in recombination frequency. As coevolved lines maintained higher genetic diversity than control lines, and because there was no evidence for heterozygote advantage or for a plastic response of recombination to infection, the observed increase in recombination most likely represented an adaptive host response under Red Queen dynamics. Conclusions This study provides direct, experimental evidence for an increase in recombination frequency under host-parasite coevolution in an obligatory outcrossing species. Combined with earlier results, the Red Queen process is the most likely explanation for this observation. PMID:22330615

2012-01-01

245

Evolution of host resistance to parasite infection in the snailschistosomehuman system  

Microsoft Academic Search

The evolutionary strategies that emerge within populations can be dictated by numerous factors, including interactions with\\u000a other species. In this paper, we explore the consequences of such a scenario using a hostparasite system of human concern.\\u000a By analyzing the dynamical behaviors of a mathematical model we investigate the evolutionary outcomes resulting from interactions\\u000a between Schistosoma mansoni and its snail and

Yiding Yang; Zhilan Feng; Dashun Xu; Gregory J. Sandland; Dennis J. Minchella

246

Host-Parasite Relationship in Cystic Echinococcosis: An Evolving Story  

PubMed Central

The larval stage of Echinococcus granulosus causes cystic echinococcosis, a neglected infectious disease that constitutes a major public health problem in developing countries. Despite being under constant barrage by the immune system, E. granulosus modulates antiparasite immune responses and persists in the human hosts with detectable humoral and cellular responses against the parasite. In vitro and in vivo immunological approaches, together with molecular biology and immunoproteomic technologies, provided us exciting insights into the mechanisms involved in the initiation of E. granulosus infection and the consequent induction and regulation of the immune response. Although the last decade has clarified many aspects of host-parasite relationship in human cystic echinococcosis, establishing the full mechanisms that cause the disease requires more studies. Here, we review some of the recent developments and discuss new avenues in this evolving story of E. granulosus infection in man. PMID:22110535

Siracusano, Alessandra; Delunardo, Federica; Teggi, Antonella; Ortona, Elena

2012-01-01

247

Sex-specific effects of a parasite evolving in a female-biased host population  

PubMed Central

Background Males and females differ in many ways and might present different opportunities and challenges to their parasites. In the same way that parasites adapt to the most common host type, they may adapt to the characteristics of the host sex they encounter most often. To explore this hypothesis, we characterized host sex-specific effects of the parasite Pasteuria ramosa, a bacterium evolving in naturally, strongly, female-biased populations of its host Daphnia magna. Results We show that the parasite proliferates more successfully in female hosts than in male hosts, even though males and females are genetically identical. In addition, when exposure occurred when hosts expressed a sexual dimorphism, females were more infected. In both host sexes, the parasite causes a similar reduction in longevity and leads to some level of castration. However, only in females does parasite-induced castration result in the gigantism that increases the carrying capacity for the proliferating parasite. Conclusions We show that mature male and female Daphnia represent different environments and reveal one parasite-induced symptom (host castration), which leads to increased carrying capacity for parasite proliferation in female but not male hosts. We propose that parasite induced host castration is a property of parasites that evolved as an adaptation to specifically exploit female hosts. PMID:23249484

2012-01-01

248

Heterogeneous hosts: how variation in host size, behaviour and immunity affects parasite aggregation.  

PubMed

Infection heterogeneity is one of the most fundamental patterns in disease ecology, yet surprisingly few studies have experimentally explored its underlying drivers. Here, we used large-scale field assessments to evaluate the degree of parasite aggregation within amphibian host populations followed by a novel experimental approach to assess the potential influence of host size, behaviour and immunity in reproducing such heterogeneity. Among 227 wetlands, 2468 hosts and seven parasite species, infections were consistently aggregated among host individuals within populations of the Pacific chorus frog (Pseudacris regilla). For each parasite species, the relationship between the log-mean and log-variance of infection load was strongly linear (R(2) : 091-098) with a slope between 137 and 167, indicative of aggregation relative to the expected Poisson slope of unity. In laboratory trials with P.regilla and the most virulent trematode (Ribeiroia ondatrae), experimental reductions in either host immunity (through corticosterone exposure) or antiparasite behaviours (through anaesthesia exposure) increased parasite infection loads in isolated hosts by 62-102% relative to unmanipulated individuals. In a second experiment designed to test how variation in host immunity, behaviour and body size affected variation in infection load within small groups (dyads), a reduction in immune function or behaviour of one host significantly amplified infection heterogeneity within the group, effectively doubling the variance-to-mean ratio. However, immunity affected aggregation only in the absence of behavioural manipulation, and changing the size distribution of hosts did not appreciably affect aggregation. Using Taylor's Power Law to integrate field and laboratory data, we found that only treatments involving behavioural reductions achieved aggregation levels comparable to natural host populations. Thus, despite their short duration, our treatments generated heterogeneity in infection loads similar to natural observations. These results emphasize how, alongside extrinsic variation in parasite exposure risk, individual host attributes generally and behaviour in particular have the potential to influence infection success and parasite aggregation. Continued integration of infection heterogeneity research across space, among host species, and over time has important implications for understanding and managing human and wildlife diseases. PMID:24548254

Johnson, Pieter T J; Hoverman, Jason T

2014-02-18

249

ALTERNATIVELY ACTIVATED MACROPHAGES ACCUMULATE AT THE HOST PARASITE INTERFACE AND CONTRIBUTE TO PROTECTION AGAINST A NEMATODE PARASITE.  

Technology Transfer Automated Retrieval System (TEKTRAN)

The mechanisms leading to host protection against intestinal nematode parasites are little understood, although physiological changes in the intestines are sighted as primary host-defense mechanisms. The memory response to Heligmosomoides polygyrus, a natural murine gastrointestinal helminth parasi...

250

Trophic Structure in a Seabird Host-Parasite Food Web: Insights from Stable Isotope Analyses  

PubMed Central

Ecological studies on food webs rarely include parasites, partly due to the complexity and dimensionality of host-parasite interaction networks. Multiple co-occurring parasites can show different feeding strategies and thus lead to complex and cryptic trophic relationships, which are often difficult to disentangle by traditional methods. We analyzed stable isotope ratios of C (13C/12C, ?13C) and N (15N/14N, ?15N) of host and ectoparasite tissues to investigate trophic structure in 4 co-occurring ectoparasites: three lice and one flea species, on two closely related and spatially segregated seabird hosts (Calonectris shearwaters). ?13C isotopic signatures confirmed feathers as the main food resource for the three lice species and blood for the flea species. All ectoparasite species showed a significant enrichment in ?15N relatively to the host tissue consumed (discrimination factors ranged from 2 to 5 depending on the species). Isotopic differences were consistent across multiple host-ectoparasite locations, despite of some geographic variability in baseline isotopic levels. Our findings illustrate the influence of both ectoparasite and host trophic ecology in the isotopic structuring of the Calonectris ectoparasite community. This study highlights the potential of stable isotope analyses in disentangling the nature and complexity of trophic relationships in symbiotic systems. PMID:20454612

Gmez-Daz, Elena; Gonzlez-Sols, Jacob

2010-01-01

251

Predators and patterns of within-host growth can mediate both among-host competition and evolution of transmission potential of parasites.  

PubMed

Parasite prevalence shows tremendous spatiotemporal variation. Theory indicates that this variation might stem from life-history characteristics of parasites and key ecological factors. Here, we illustrate how the interaction of an important predator and the schedule of transmission potential of two parasites can explain parasite abundance. A field survey showed that a noncastrating fungus (Metschnikowia bicuspidata) commonly infected a dominant zooplankton host (Daphnia dentifera), while a castrating bacterial parasite (Pasteuria ramosa) was rare. This result seemed surprising given that the bacterium produces many more infectious propagules (spores) than the fungus upon host death. The fungus's dominance can be explained by the schedule of within-host growth of parasites (i.e., how transmission potential changes over the course of infection) and the release of spores from "sloppy" predators (Chaoborus spp., who consume Daphnia prey whole and then later regurgitate the carapace and parasite spores). In essence, sloppy predators create a niche that the faster-schedule fungus currently occupies. However, a selection experiment showed that the slower-schedule bacterium can evolve into this faster-schedule, predator-mediated niche (but pays a cost in maximal spore yield to do so). Hence, our study shows how parasite life history can interact with predation to strongly influence the ecology, epidemiology, and evolution of infectious disease. PMID:25061679

Auld, Stuart K J R; Hall, Spencer R; Housley Ochs, Jessica; Sebastian, Mathew; Duffy, Meghan A

2014-08-01

252

Mimetic host shifts in an endangered social parasite of ants.  

PubMed

An emerging problem in conservation is whether listed morpho-species with broad distributions, yet specialized lifestyles, consist of more than one cryptic species or functionally distinct forms that have different ecological requirements. We describe extreme regional divergence within an iconic endangered butterfly, whose socially parasitic young stages use non-visual, non-tactile cues to infiltrate and supplant the brood in ant societies. Although indistinguishable morphologically or when using current mitochondrial and nuclear sequence-, or microsatellite data, Maculinea rebeli from Spain and southeast Poland exploit different Myrmica ant species and experience 100 per cent mortality with each other's hosts. This reflects major differences in the hydrocarbons synthesized from each region by the larvae, which so closely mimic the recognition profiles of their respective hosts that nurse ants afford each parasite a social status above that of their own kin larvae. The two host ants occupy separate niches within grassland; thus, conservation management must differ in each region. Similar cryptic differentiation may be common, yet equally hard to detect, among the approximately 10 000 unstudied morpho-species of social parasite that are estimated to exist, many of which are Red Data Book listed. PMID:23193127

Thomas, Jeremy A; Elmes, Graham W; Sielezniew, Marcin; Stankiewicz-Fiedurek, Anna; Simcox, David J; Settele, Josef; Schnrogge, Karsten

2013-01-22

253

The impact of environmental change on hostparasite coevolutionary dynamics  

PubMed Central

Environmental factors are known to affect the strength and the specificity of interactions between hosts and parasites. However, how this shapes patterns of coevolutionary dynamics is not clear. Here, we construct a simple mathematical model to study the effect of environmental change on hostparasite coevolutionary outcome when interactions are of the matching-alleles or the gene-for-gene type. Environmental changes may effectively alter the selective pressure and the level of specialism in the population. Our results suggest that environmental change altering the specificity of selection in antagonistic interactions can produce alternating time windows of cyclical allele-frequency dynamics and cessation thereof. This type of environmental impact can also explain the maintenance of polymorphism in gene-for-gene interactions without costs. Overall, our study points to the potential consequences of environmental variation in coevolution, and thus the importance of characterizing genotype-by-genotype-by-environment interactions in natural hostparasite systems, especially those that change the direction of selection acting between the two species. PMID:21177684

Mostowy, Rafal; Engelstdter, Jan

2011-01-01

254

Does interspecies hybridization affect the host specificity of parasites in cyprinid fish?  

PubMed Central

Background Host specificity varies among parasite species. Some parasites are strictly host-specific, others show a specificity for congeneric or non-congeneric phylogenetically related host species, whilst some others are non-specific (generalists). Two cyprinids, Cyprinus carpio and Carassius gibelio, plus their respective hybrids were investigated for metazoan parasites. The aim of this study was to analyze whether interspecies hybridization affects host specificity. The different degrees of host specificity within a phylogenetic framework were taken into consideration (i.e. strict specialist, intermediate specialist, and intermediate generalist). Methods Fish were collected during harvesting the pond and identified using meristic traits and molecular markers. Metazoan parasite species were collected. Host specificity of parasites was determined using the following classification: strict specialist, intermediate specialist, intermediate generalist and generalist. Parasite species richness was compared between parental species and their hybrids. The effect of host species on abundance of parasites differing in host specificity was tested. Results Hybrids harbored more different parasite species but their total parasite abundance was lower in comparison with parental species. Interspecies hybridization affected the host specificity of ecto- and endoparasites. Parasite species exhibiting different degrees of host specificity for C. carpio and C. gibelio were also present in hybrids. The abundance of strict specialists of C. carpio was significantly higher in parental species than in hybrids. Intermediate generalists parasitizing C. carpio and C. gibelio as two phylogenetically closely related host species preferentially infected C. gibelio when compared to C. carpio, based on prevalence and maximum intensity of infection. Hybrids were less infected by intermediate generalists when compared to C. gibelio. Conclusions This finding does not support strict co-adaptation between host and parasite genotypes resulting in narrow host specificity, and showed that hybrid genotypes are susceptible to parasites exhibiting host specificity. The immune mechanisms specific to parental species might represent potential mechanisms explaining the low abundance of parasites in C. gibelio x C. carpio hybrids. PMID:23587287

2013-01-01

255

Manipulative parasites may not alter intermediate host distribution but still enhance their transmission: field evidence for increased vulnerability to definitive hosts and non-host predator avoidance.  

PubMed

Behavioural alterations induced by parasites in their intermediate hosts can spatially structure host populations, possibly resulting in enhanced trophic transmission to definitive hosts. However, such alterations may also increase intermediate host vulnerability to non-host predators. Parasite-induced behavioural alterations may thus vary between parasite species and depend on each parasite definitive host species. We studied the influence of infection with 2 acanthocephalan parasites (Echinorhynchus truttae and Polymorphus minutus) on the distribution of the amphipod Gammarus pulex in the field. Predator presence or absence and predator species, whether suitable definitive host or dead-end predator, had no effect on the micro-distribution of infected or uninfected G. pulex amphipods. Although neither parasite species seem to influence intermediate host distribution, E. truttae infected G. pulex were still significantly more vulnerable to predation by fish (Cottus gobio), the parasite's definitive hosts. In contrast, G. pulex infected with P. minutus, a bird acanthocephalan, did not suffer from increased predation by C. gobio, a predator unsuitable as host for P. minutus. These results suggest that effects of behavioural changes associated with parasite infections might not be detectable until intermediate hosts actually come in contact with predators. However, parasite-induced changes in host spatial distribution may still be adaptive if they drive hosts into areas of high transmission probabilities. PMID:23068018

Lagrue, C; Gvenatam, A; Bollache, L

2013-02-01

256

Host selection and parasite infection in Aedes taeniorhynchus, endemic disease vector in the Galpagos Islands.  

PubMed

Host selection in blood-sucking arthropods has important evolutionary and ecological implications for the transmission dynamics, distribution and host-specificity of the parasites they transmit. The black salt-marsh mosquito (Aedes taeniorhynchus Wiedemann) is distributed throughout tropical to temperate coastal zones in the Americas, and continental populations are primarily mammalphilic. It is the only indigenous mosquito in the Galpagos Islands, having colonised the archipelago around 200,000 years ago, potentially adapting its host selection, and in the process, altering the dynamics of vector mediated pathogen interactions in the archipelago. Here, we use blood-meal analysis and PCR-based parasite screening approach to determine the blood-feeding patterns of A. taeniorhynchus in the Galpagos Islands and identify potential parasite transmission with which this mosquito could be involved. Our results show that A. taeniorhynchus feeds equally on mammals and reptiles, and only one avian sample was observed in 190 successful PCR amplifications from blood meals. However, we detected endemic filarial worms and Haemoproteus parasites known to infect various Galpagos bird species in mosquito thoraces, suggesting that feeding on birds must occur at low frequency, and that A. taeniorhynchus may play a role in maintaining some avian vector-borne pathogens, although more work is needed to explore this possibility. We also isolated three different DNA sequences corresponding to hemogregarine parasites of the genus Hepatozoon from mosquito and iguana blood samples, suggesting that more than one species of Hepatozoon parasites are present in Galpagos. Phylogenetic analysis of Hepatozoon 18sRNA sequences indicates that A. taeniorhynchus may have facilitated a recent breakdown in host-species association of formerly isolated Hepatozoon spp. infecting the reptile populations in the Galpagos Islands. PMID:22921730

Bataille, Arnaud; Fourni, Guillaume; Cruz, Marilyn; Cedeo, Virna; Parker, Patricia G; Cunningham, Andrew A; Goodman, Simon J

2012-12-01

257

Different meal, same flavor: cospeciation and host switching of haemosporidian parasites in some non-passerine birds  

PubMed Central

Background Previous studies have shown that haemosporidian parasites (Haemoproteus (Parahaemoproteus) and Plasmodium) infecting passerine birds have an evolutionary history of host switching with little cospeciation, in particular at low taxonomic levels (e.g., below the family level), which is suggested as the main speciation mechanism of this group of parasites. Recent studies have characterized diverse clades of haemosporidian parasites (H. (Haemoproteus) and H. (Parahaemoproteus)) infecting non-passerine birds (e.g., Columbiformes, Pelecaniiformes). Here, we explore the cospeciation history of H. (Haemoproteus) and H. (Parahaemoproteus) parasites with their non-passerine hosts. Methods We sequenced the mtDNA cyt b gene of both haemosporidian parasites and their avian non-passerine hosts. We built Bayesian phylogenetic hypotheses and created concensus phylograms that were subsequently used to conduct cospeciation analyses. We used both a global cospeciation test, PACo, and an event-cost algorithm implemented in CoRe-PA. Results The global test suggests that H. (Haemoproteus) and H. (Parahaemoproteus) parasites have a diversification history dominated by cospeciation events particularly at the family level. Host-parasite links from the PACo analysis show that host switching events are common within families (i.e., among genera and among species within genera), and occasionally across different orders (e.g., Columbiformes to Pelecaniiformes). Event-cost analyses show that haemosporidian coevolutionary history is dominated by host switching and some codivergence, but with duplication events also present. Genetic lineages unique to raptor species (e.g., FALC11) commonly switch between Falconiformes and Strigiformes. Conclusions Our results corroborate previous findings that have detected a global cospeciation signal at the family taxonomic level, and they also support a history of frequent switching closer to the tips of the host phylogeny, which seems to be the main diversification mechanism of haemosporidians. Such dynamic host-parasite associations are relevant to the epidemiology of emerging diseases because low parasite host specificity is a prerequisite for the emergence of novel diseases. The evidence on host distributions suggests that haemosporidian parasites have the potential to rapidly develop novel host-associations. This pattern has also been recorded in fish-monogenean interactions, suggesting a general diversification mechanism for parasites when host choice is not restricted by ecological barriers. PMID:24957563

2014-01-01

258

Distance decay of similarity among parasite communities of three marine invertebrate hosts  

Microsoft Academic Search

The similarity in species composition between two communities generally decays as a function of increasing distance between\\u000a them. Parasite communities in vertebrate definitive hosts follow this pattern but the respective relationship in intermediate\\u000a invertebrate hosts of parasites with complex life cycles is unknown. In intermediate hosts, parasite communities are affected\\u000a not only by the varying vagility of their definitive hosts

David W. Thieltges; MacNeill A. D. Ferguson; Cathy S. Jones; Manuela Krakau; Xavier de Montaudouin; Leslie R. Noble; Karsten Reise; Robert Poulin

2009-01-01

259

Do threatened hosts have fewer parasites? A comparative study in primates  

Microsoft Academic Search

Summary 1. Parasites and infectious diseases have become a major concern in conservation biology, in part because they can trigger or accelerate species or population declines. Focusing on primates as a well-studied host clade, we tested whether the species richness and prevalence of parasites differed between threatened and non-threatened host species. 2. We collated data on 386 species of parasites

SONIA ALTIZER; CHARLES L. NUNN; PATRIK LINDENFORS

2007-01-01

260

1 Introduction New developments in the study of host-parasite phylogenies have given insights into  

E-print Network

1 Introduction New developments in the study of host-parasite phylogenies have given insights of an association between hosts and parasites (Page, 2003). However, there are no reliable statistical tests phyloge- nies imply a lack of cospeciation. Parasites have long been used to make infer- ences about

Barber, Stuart

261

A quantitative test of the relationship between parasite dose and infection probability across different hostparasite combinations  

PubMed Central

Epidemiological models generally assume that the number of susceptible individuals that become infected within a unit of time depends on the density of the hosts and the concentration of parasites (i.e. mass-action principle). However, empirical studies have found significant deviations from this assumption due to biotic and abiotic factors, such as seasonality, the spatial structure of the host population and host heterogeneity with respect to immunity and susceptibility. In this paper, we examine the effect of the dose level of the bacterial endoparasite Pasteuria ramosa on the infection rate of its host, the water flea Daphnia magna. Using seven host clones and two parasite isolates, we measure the fraction of infected hosts after exposure to eight different parasite doses to determine whether there is variation in the infection process across different host cloneparasite isolate combinations. In five combinations, a pronounced dose-dependent infection pattern was found. Using a likelihood approach, we compare the infection data of these five combinations to the fit of three mathematical models: a mass-action model, a parasite antagonism model (i.e. an increase in the parasite dose leads to an under-proportionate increase in the infection rate per host) and a heterogeneous host model. We found that the host heterogeneity model, in which we assumed the existence of non-inherited phenotypic differences in host susceptibilities to the parasite, provides the best fit. Our analysis suggests that among 5 out of the 14 host cloneparasite isolate combinations that resulted in appreciable infections, non-genetic host heterogeneity plays an important role. PMID:18198145

Ben-Ami, Frida; Regoes, Roland R; Ebert, Dieter

2008-01-01

262

A quantitative test of the relationship between parasite dose and infection probability across different host-parasite combinations.  

PubMed

Epidemiological models generally assume that the number of susceptible individuals that become infected within a unit of time depends on the density of the hosts and the concentration of parasites (i.e. mass-action principle). However, empirical studies have found significant deviations from this assumption due to biotic and abiotic factors, such as seasonality, the spatial structure of the host population and host heterogeneity with respect to immunity and susceptibility. In this paper, we examine the effect of the dose level of the bacterial endoparasite Pasteuria ramosa on the infection rate of its host, the water flea Daphnia magna. Using seven host clones and two parasite isolates, we measure the fraction of infected hosts after exposure to eight different parasite doses to determine whether there is variation in the infection process across different host clone-parasite isolate combinations. In five combinations, a pronounced dose-dependent infection pattern was found. Using a likelihood approach, we compare the infection data of these five combinations to the fit of three mathematical models: a mass-action model, a parasite antagonism model (i.e. an increase in the parasite dose leads to an under-proportionate increase in the infection rate per host) and a heterogeneous host model. We found that the host heterogeneity model, in which we assumed the existence of non-inherited phenotypic differences in host susceptibilities to the parasite, provides the best fit. Our analysis suggests that among 5 out of the 14 host clone-parasite isolate combinations that resulted in appreciable infections, non-genetic host heterogeneity plays an important role. PMID:18198145

Ben-Ami, Frida; Regoes, Roland R; Ebert, Dieter

2008-04-01

263

Molecular mimicry between host and pathogen: examples from parasites and implication  

Microsoft Academic Search

The studies summarized in this paper suggest that parasites may trigger activation of autoimmune mechanisms. The association between parasites and autoimmunity could by manifested by the development of pathogenic anti-parasitic antibodies and cytotoxic T cells that attack and damage self tissues as a result of molecular mimicry between host and parasites. On the other hand, the homology between self and

Mahmoud Abu-Shakra; Dan Buskila; Yehuda Shoenfeld

1999-01-01

264

Heritable variation in host tolerance and resistance inferred from a wild host-parasite system.  

PubMed

Hosts have evolved two distinct defence strategies against parasites: resistance (which prevents infection or limit parasite growth) and tolerance (which alleviates the fitness consequences of infection). However, heritable variation in resistance and tolerance and the genetic correlation between these two traits have rarely been characterized in wild host populations. Here, we estimate these parameters for both traits in Leuciscus burdigalensis, a freshwater fish parasitized by Tracheliastes polycolpus. We used a genetic database to construct a full-sib pedigree in a wild L. burdigalensis population. We then used univariate animal models to estimate inclusive heritability (i.e. all forms of genetic and non-genetic inheritance) in resistance and tolerance. Finally, we assessed the genetic correlation between these two traits using a bivariate animal model. We found significant heritability for resistance (H = 17.6%; 95% CI: 7.2-32.2%) and tolerance (H = 18.8%; 95% CI: 4.4-36.1%), whereas we found no evidence for the existence of a genetic correlation between these traits. Furthermore, we confirm that resistance and tolerance are strongly affected by environmental effects. Our results demonstrate that (i) heritable variation exists for parasite resistance and tolerance in wild host populations, and (ii) these traits can evolve independently in populations. PMID:24478295

Maz-Guilmo, Elise; Loot, Graldine; Pez, David J; Lefvre, Thierry; Blanchet, Simon

2014-03-22

265

Brood parasitism by brown-headed cowbirds and the expression of sexual characters in their hosts.  

PubMed

Interspecific brood parasites may use the secondary sexual characters of the hosts to decide which species to parasitize. Hence, species with conspicuous and well-recognisable traits may have higher chances of becoming parasitised. Using North American birds and their frequent brood parasite, the brown-headed cowbird Molothrus ater, we tested the relationship between features of song and plumage coloration of hosts and the frequency of brood parasitism while controlling for several potentially confounding factors. Relying on two sets of analysis, we focused separately on the evolutionary view of the parasite and the host. From the cowbird's perspective, we found that males of heavily parasitized species posit songs with low syllable repertoire size, shorter inter-song interval and have brighter plumage. From the host's perspective, a phylogenetic analysis revealed similar associations for features of song, but not for plumage characteristics that were unrelated to brood parasitism. These comparative findings may imply that brood parasites choose novel hosts based on heterospecific signals; and/or host species working against sexual selection escape from brood parasitism by evolving inconspicuous sexual signals. Although our data do not allow us to distinguish between these two evolutionary scenarios, our results suggest that selection factors mediating cowbird parasitism via host recognition by heterospecific signals may have an important role in the evolutionary relationship between brood parasites and their hosts. PMID:15647904

Garamszegi, Lszl Zsolt; Avils, Jess Miguel

2005-03-01

266

Parasite-induced aggression and impaired contest ability in a fish host  

Microsoft Academic Search

BACKGROUND: Success of trophically transmitted parasites depends to a great extent on their ability to manipulate their intermediate hosts in a way that makes them easier prey for target hosts. Parasite-induced behavioural changes are the most spectacular and diverse examples of manipulation. Most of the studies have been focused on individual behaviour of hosts including fish. We suggest that agonistic

V N Mikheev; A F Pasternak; J Taskinen; E T Valtonen

2010-01-01

267

Competitive Interactions between Parasitoids Provide New Insight into Host Suppression  

PubMed Central

Understanding the dynamics of potential inter- and intraspecific competition in parasitoid communities is crucial in the screening of efficient parasitoid species and for utilization of the best parasitoid species combinations. In this respect, the host-parasitoid systems, Bemisia tabaci and two parasitoids, Eretmocerus hayati (exotic) and Encarsia sophia (existing) were studied under laboratory conditions to investigate whether interference competition between the exotic and existing species occurs as well as the influence of potential interference competition on the suppression of the host B. tabaci. Studies on interspecific-, intraspecific- and self-interference competition in two parasitoid species were conducted under both rich and limited host resource conditions. Results showed that (1) both parasitoid species negatively affect the progeny production of the other under both rich and limited host resource conditions; (2) both parasitoid species interfered intraspecifically on conspecific parasitized hosts when the available hosts are scarce and; 3) the mortality of B. tabaci induced by parasitoids via parasitism, host-feeding or both parasitism and host-feeding together varied among treatments under different host resource conditions, but showed promise for optimizing control strategies. As a result of our current findings, we suggest a need to investigate the interactions between the two parasitoids on continuous generations. PMID:24312394

Wan, Fang-Hao

2013-01-01

268

The evolution of virulence when parasites cause host castration and gigantism.  

PubMed

It has been suggested that the harm parasites cause to their hosts is an unavoidable consequence of parasite reproduction with costs not only for the host but also for the parasite. Castrating parasites are thought to minimize their costs by reducing host fecundity, which may minimize the chances of killing both host and parasite prematurely. We conducted a series of experiments to understand the evolution of virulence of a castrating bacterium in the planktonic crustacean Daphnia magna. By manipulating food levels during the infection of D. magna with the bacterium Pasteuria ramosa, we showed that both antagonists are resource-limited and that a negative correlation between host and parasite reproduction exists, indicating resource competition among the antagonists. Pasteuria ramosa also induces enhanced growth of its hosts (gigantism), which we found to be negatively correlated with host fecundity but positively correlated with parasite reproduction. Because infected hosts never recovered from infections, we concluded that gigantism is beneficial only for the parasite. Hosts, however, have evolved counteradaptations. We showed that infected hosts have enhanced reproduction before castration. This shift to earlier reproduction increases overall host fecundity and compromises parasite reproduction. Finally, we showed that this resource conflict is subject to genetic variation among host and parasite genotypes within a population and is therefore likely to be an important force in the coevolution of virulence in this system. A verbal model is presented and suggests that the adaptive value of gigantism is to store host resources, which are liberated after parasitic castration for later use by the growing parasite. This hypothesis assumes that infections are long lasting, that is, that they have a high life expectancy. PMID:15540139

Ebert, Dieter; Carius, Hans Joachim; Little, Tom; Decaestecker, Ellen

2004-11-01

269

Interactions between the hemiparasitic angiosperm Rhinanthus minor and its hosts: From the cell to the ecosystem  

Microsoft Academic Search

Parasitic plants can significantly influence the species to which they attach. The host response is variable however, and\\u000a ranges from death of the host to no detectable effects in terms of both growth and physiology. The parasite can directly influence\\u000a its hosts through resource abstraction, and indirectly by influencing inter- and intra-specific interactions. Abiotic factors\\u000a interact with these direct and

Duncan D. Cameron; Jun-Kwon Hwangbo; Aidan M. Keith; Jean-Michel Geniez; Daniel Kraushaar; Jenny Rowntree; Wendy E. Seel

2005-01-01

270

Egg color variation, but not egg rejection behavior, changes in a cuckoo host breeding in the absence of brood parasitism  

PubMed Central

Interactions between parasitic cuckoos and their songbird hosts form a classical reciprocal arms race, and are an excellent model for understanding the process of coevolution. Changes in host egg coloration via the evolution of interclutch variation in egg color or intraclutch consistency in egg color are hypothesized counter adaptations that facilitate egg recognition and thus limit brood parasitism. Whether these antiparasitism strategies are maintained when the selective pressure of parasitism is relaxed remains debated. However, introduced species provide unique opportunities for testing the direction and extent of natural selection on phenotypic trait maintenance and variation. Here, we investigated egg rejection behavior and egg color polymorphism in the red-billed leiothrix (Leiothrix lutea), a common cuckoo (Cuculus canorus) host, in a population introduced to Hawaii 100 years ago (breeding without cuckoos) and a native population in China (breeding with cuckoos). We found that egg rejection ability was equally strong in both the native and the introduced populations, but levels of interclutch variation and intraclutch consistency in egg color in the native population were higher than in the introduced population. This suggests that egg rejection behavior in hosts can be maintained in the absence of brood parasitism and that egg appearance is maintained by natural selection as a counter adaptation to brood parasitism. This study provides rare evidence that host antiparasitism strategies can change under parasite-relaxed conditions and reduced selection pressure. PMID:25360264

Yang, Canchao; Liu, Yang; Zeng, Lijin; Liang, Wei

2014-01-01

271

The Role of Host Traits, Season and Group Size on Parasite Burdens in a Cooperative Mammal  

PubMed Central

The distribution of parasites among hosts is often characterised by a high degree of heterogeneity with a small number of hosts harbouring the majority of parasites. Such patterns of aggregation have been linked to variation in host exposure and susceptibility as well as parasite traits and environmental factors. Host exposure and susceptibility may differ with sexes, reproductive effort and group size. Furthermore, environmental factors may affect both the host and parasite directly and contribute to temporal heterogeneities in parasite loads. We investigated the contributions of host and parasite traits as well as season on parasite loads in highveld mole-rats (Cryptomys hottentotus pretoriae). This cooperative breeder exhibits a reproductive division of labour and animals live in colonies of varying sizes that procreate seasonally. Mole-rats were parasitised by lice, mites, cestodes and nematodes with mites (Androlaelaps sp.) and cestodes (Mathevotaenia sp.) being the dominant ecto- and endoparasites, respectively. Sex and reproductive status contributed little to the observed parasite prevalence and abundances possibly as a result of the shared burrow system. Clear seasonal patterns of parasite prevalence and abundance emerged with peaks in summer for mites and in winter for cestodes. Group size correlated negatively with mite abundance while it had no effect on cestode burdens and group membership affected infestation with both parasites. We propose that the mode of transmission as well as social factors constrain parasite propagation generating parasite patterns deviating from those commonly predicted. PMID:22069481

Viljoen, Hermien; Bennett, Nigel C.; Ueckermann, Edward A.; Lutermann, Heike

2011-01-01

272

Parasite diversity and coinfection determine pathogen infection success and host fitness  

PubMed Central

While the importance of changes in host biodiversity for disease risk continues to gain empirical support, the influence of natural variation in parasite diversity on epidemiological outcomes remains largely overlooked. Here, we combined field infection data from 2,191 amphibian hosts representing 158 parasite assemblages with mechanistic experiments to evaluate the influence of parasite richness on both parasite transmission and host fitness. Using a guild of larval trematode parasites (six species) and an amphibian host, our experiments contrasted the effects of parasite richness vs. composition, observed vs. randomized assemblages, and additive vs. replacement designs. Consistent with the dilution effect hypothesis extended to intrahost diversity, increases in parasite richness reduced overall infection success, including infections by the most virulent parasite. However, the effects of parasite richness on host growth and survival were context dependent; pathology increased when parasites were administered additively, even when the presence of the most pathogenic species was held constant, but decreased when added species replaced or reduced virulent species, emphasizing the importance of community composition and assembly. These results were similar or stronger when community structures were weighted by their observed frequencies in nature. The field data also revealed the highly nested structure of parasite assemblages, with virulent species generally occupying basal positions, suggesting that increases in parasite richness and antagonism in nature will decrease virulent infections. Our findings emphasize the importance of parasite biodiversity and coinfection in affecting epidemiological responses and highlight the value of integrating research on biodiversity and community ecology for understanding infectious diseases. PMID:22615371

Johnson, Pieter T. J.; Hoverman, Jason T.

2012-01-01

273

Toxoplasma gondii Dissemination: A Parasite's Journey through the Infected Host.  

PubMed

T. gondii is a highly successful global pathogen that is remarkable in its ability to infect nearly any nucleated cell in any warm-blooded animal. Infection with T. gondii typically occurs through the ingestion of contaminated food or water, but the parasite then breaches the intestinal epithelial barrier and spreads from the lamina propria to a large variety of other organs in the body. A key feature of T. gondii pathogenesis is the parasite's ability to cross formidable biological barriers in the infected host and enter tissues such as the brain, eye, and placenta. The dissemination of T. gondii into these organs underlies the severe disease that accompanies human toxoplasmosis. In this review we will focus on seminal studies as well as exciting recent findings that have shaped our current understanding of the cellular and molecular mechanisms by which T. gondii journeys throughout the host and enters the vital organs to cause disease. This article is protected by copyright. All rights reserved. PMID:25408224

Harker, Katherine S; Ueno, Norikiyo; Lodoen, Melissa B

2014-11-19

274

Behavioral Ecology Vol. 12 No. 1: 3140 Host activity and the risk of nest parasitism by  

E-print Network

(Dendroica petechia), and American redstarts (Setophaga ruticilla). Daily probability of parasitism varied of hosts during nest building to locate nests. Key words: American redstart (Setophaga ruticilla), brood

Martin, Thomas E.

275

Impacts of a native parasitic plant on an introduced and a native host species: implications for the control of an invasive weed  

PubMed Central

Background and Aims While invasive species may escape from natural enemies in the new range, the establishment of novel biotic interactions with species native to the invaded range can determine their success. Biological control of plant populations can be achieved by manipulation of a species' enemies in the invaded range. Interactions were therefore investigated between a native parasitic plant and an invasive legume in Mediterranean-type woodlands of South Australia. Methods The effects of the native stem parasite, Cassytha pubescens, on the introduced host, Cytisus scoparius, and a co-occurring native host, Leptospermum myrsinoides, were compared. The hypothesis that the parasitic plant would have a greater impact on the introduced host than the native host was tested. In a field study, photosynthesis, growth and survival of hosts and parasite were examined. Key Results As predicted, Cassytha had greater impacts on the introduced host than the native host. Dead Cytisus were associated with dense Cassytha infections but mortality of Leptospermum was not correlated with parasite infection. Cassytha infection reduced the photosynthetic rates of both hosts. Infected Cytisus showed slower recovery of photosystem II efficiency, lower transpiration rates and reduced photosynthetic biomass in comparison with uninfected plants. Parasite photosynthetic rates and growth rates were higher when growing on the introduced host Cytisus, than on Leptospermum. Conclusions Infection by a native parasitic plant had strong negative effects on the physiology and above-ground biomass allocation of an introduced species and was correlated with increased plant mortality. The greater impact of the parasite on the introduced host may be due to either the greater resources that this host provides or increased resistance to infection by the native host. This disparity of effects between introduced host and native host indicates the potential for Cassytha to be exploited as a control tool. PMID:19001426

Prider, Jane; Watling, Jennifer; Facelli, Jos M.

2009-01-01

276

The Role of Extracellular Vesicles in Modulating the Host Immune Response during Parasitic Infections  

PubMed Central

Parasites are the cause of major diseases affecting billions of people. As the inflictions caused by these parasites affect mainly developing countries, they are considered as neglected diseases. These parasitic infections are often chronic and lead to significant immunomodulation of the host immune response by the parasite, which could benefit both the parasite and the host and are the result of millions of years of co-evolution. The description of parasite extracellular vesicles (EVs) in protozoa and helminths suggests that they may play an important role in hostparasite communication. In this review, recent studies on parasitic (protozoa and helminths) EVs are presented and their potential use as novel therapeutical approaches is discussed. PMID:25250031

Montaner, Sergio; Galiano, Alicia; Trelis, Mara; Martin-Jaular, Lorena; del Portillo, Hernando A.; Bernal, Dolores; Marcilla, Antonio

2014-01-01

277

Specific developmental pathways underlie host specificity in the parasitic plant Orobanche  

PubMed Central

Parasitic angiosperms are an ecologically and economically important group of plants. However our understanding of the basis for host specificity in these plants is embryonic. Recently we investigated host specificity in the parasitic angiosperm Orobanche minor, and demonstrated that this host generalist parasite comprises genetically defined races that are physiologically adapted to specific hosts. Populations occurring naturally on red clover (Trifolium pratense) and sea carrot (Daucus carota subsp. gummifer) respectively, showed distinct patterns of host specificity at various developmental stages, and a higher fitness on their natural hosts, suggesting these races are locally adapted. Here we discuss the implications of our findings from a broader perspective. We suggest that differences in signal responsiveness and perception by the parasite, as well as qualitative differences in signal production by the host, may elicit host specificity in this parasitic plant. Together with our earlier demonstration that these O. minor races are genetically distinct based on molecular markers, our recent data provide a snapshot of speciation in action, driven by host specificity. Indeed, host specificity may be an underestimated catalyst for speciation in parasitic plants generally. We propose that identifying host specific races using physiological techniques will complement conventional molecular marker-based approaches to provide a framework for delineating evolutionary relationships among cryptic host-specific parasitic plants. PMID:20081361

Hiscock, Simon

2010-01-01

278

Born in an Alien Nest : How Do Social Parasite Male Offspring Escape from Host Aggression?  

PubMed Central

Social parasites exploit the colony resources of social insects. Some of them exploit the host colony as a food resource or as a shelter whereas other species also exploit the brood care behavior of their social host. Some of these species have even lost the worker caste and rely completely on the host's worker force to rear their offspring. To avoid host defenses and bypass their recognition code, these social parasites have developed several sophisticated chemical infiltration strategies. These infiltration strategies have been highly studied in several hymenopterans. Once a social parasite has successfully entered a host nest and integrated its social system, its emerging offspring still face the same challenge of avoiding host recognition. However, the strategy used by the offspring to survive within the host nest without being killed is still poorly documented. In cuckoo bumblebees, the parasite males completely lack the morphological and chemical adaptations to social parasitism that the females possess. Moreover, young parasite males exhibit an early production of species-specific cephalic secretions, used as sexual pheromones. Host workers might thus be able to recognize them. Here we used a bumblebee host-social parasite system to test the hypothesis that social parasite male offspring exhibit a chemical defense strategy to escape from host aggression during their intranidal life. Using behavioral assays, we showed that extracts from the heads of young cuckoo bumblebee males contain a repellent odor that prevents parasite males from being attacked by host workers. We also show that social parasitism reduces host worker aggressiveness and helps parasite offspring acceptance. PMID:23028441

Lhomme, Patrick; Ayasse, Manfred; Valterov, Irena; Lecocq, Thomas; Rasmont, Pierre

2012-01-01

279

A Trypanosoma brucei Kinesin Heavy Chain Promotes Parasite Growth by Triggering Host Arginase Activity  

PubMed Central

Background In order to promote infection, the blood-borne parasite Trypanosoma brucei releases factors that upregulate arginase expression and activity in myeloid cells. Methodology/Principal findings By screening a cDNA library of T. brucei with an antibody neutralizing the arginase-inducing activity of parasite released factors, we identified a Kinesin Heavy Chain isoform, termed TbKHC1, as responsible for this effect. Following interaction with mouse myeloid cells, natural or recombinant TbKHC1 triggered SIGN-R1 receptor-dependent induction of IL-10 production, resulting in arginase-1 activation concomitant with reduction of nitric oxide (NO) synthase activity. This TbKHC1 activity was IL-4R?-independent and did not mirror M2 activation of myeloid cells. As compared to wild-type T. brucei, infection by TbKHC1 KO parasites was characterized by strongly reduced parasitaemia and prolonged host survival time. By treating infected mice with ornithine or with NO synthase inhibitor, we observed that during the first wave of parasitaemia the parasite growth-promoting effect of TbKHC1-mediated arginase activation resulted more from increased polyamine production than from reduction of NO synthesis. In late stage infection, TbKHC1-mediated reduction of NO synthesis appeared to contribute to liver damage linked to shortening of host survival time. Conclusion A kinesin heavy chain released by T. brucei induces IL-10 and arginase-1 through SIGN-R1 signaling in myeloid cells, which promotes early trypanosome growth and favors parasite settlement in the host. Moreover, in the late stage of infection, the inhibition of NO synthesis by TbKHC1 contributes to liver pathogenicity. PMID:24204274

De Muylder, Graldine; Dauloude, Sylvie; Lecordier, Laurence; Uzureau, Pierrick; Morias, Yannick; Van Den Abbeele, Jan; Caljon, Guy; Hrin, Michel; Holzmuller, Philippe; Semballa, Silla; Courtois, Pierrette; Vanhamme, Luc; Stijlemans, Benot; De Baetselier, Patrick; Barrett, Michael P.; Barlow, Jillian L.; McKenzie, Andrew N. J.; Barron, Luke; Wynn, Thomas A.; Beschin, Alain; Vincendeau, Philippe; Pays, Etienne

2013-01-01

280

Interactions among four parasite species in an amphipod population from Patagonia.  

PubMed

Parasites commonly share their hosts with specimens of the same or different parasite species, resulting in multiple parasites obtaining resources from the same host. This could potentially lead to conflicts between co-infecting parasites, especially at high infection intensities. In Pool Los Juncos (Patagonia, Argentina), the amphipod Hyalella patagonica is an intermediate host to three parasites that mature in birds (the acanthocephalan Pseudocorynosoma sp. and larval stages of two Cyclophyllidea cestodes), in addition to a microsporidian (Thelohania sp.), whose life cycle is unknown, but very likely to be monoxenous. The aim of this study was to describe interactions between these parasite species in their amphipod host population. Amphipods were collected monthly between June 2002 and January 2004 to assess parasite infection. Infection prevalence and mean intensity were greatest in larger male amphipods for all parasite species. We also found a positive association between Thelohania sp. and both Pseudocorynosoma sp. and Cyclophyllidea sp. 1 infections, though Pseudocorynosoma sp. and Cyclophyllidea sp. 1 were negatively associated with each other. We conclude that contrasting associations between parasite species may be associated with competition for both food intake and space in the haemocoel. PMID:22335997

Rauque, C A; Semenas, L

2013-03-01

281

Habitat selection for parasite-free space by hosts of parasitic Jukka T. Forsman and Thomas E. Martin  

E-print Network

Habitat selection for parasite-free space by hosts of parasitic cowbirds Jukka T. Forsman Unit, Univ. of Montana, Missoula, MT 59812, USA. Choice of breeding habitat can have a major impact on fitness. Sensitivity of habitat choice to environmental cues predicting reproductive success

Martin, Thomas E.

282

Heterogeneous Host Susceptibility Enhances Prevalence of Mixed-Genotype Micro-Parasite Infections  

PubMed Central

Dose response in micro-parasite infections is usually shallower than predicted by the independent action model, which assumes that each infectious unit has a probability of infection that is independent of the presence of other infectious units. Moreover, the prevalence of mixed-genotype infections was greater than predicted by this model. No probabilistic infection model has been proposed to account for the higher prevalence of mixed-genotype infections. We use model selection within a set of four alternative models to explain high prevalence of mixed-genotype infections in combination with a shallow dose response. These models contrast dependent versus independent action of micro-parasite infectious units, and homogeneous versus heterogeneous host susceptibility. We specifically consider a situation in which genome differences between genotypes are minimal, and highly unlikely to result in genotype-genotype interactions. Data on dose response and mixed-genotype infection prevalence were collected by challenging fifth instar Spodoptera exigua larvae with two genotypes of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV), differing only in a 100 bp PCR marker sequence. We show that an independent action model that includes heterogeneity in host susceptibility can explain both the shallow dose response and the high prevalence of mixed-genotype infections. Theoretical results indicate that variation in host susceptibility is inextricably linked to increased prevalence of mixed-genotype infections. We have shown, to our knowledge for the first time, how heterogeneity in host susceptibility affects mixed-genotype infection prevalence. No evidence was found that virions operate dependently. While it has been recognized that heterogeneity in host susceptibility must be included in models of micro-parasite transmission and epidemiology to account for dose response, here we show that heterogeneity in susceptibility is also a fundamental principle explaining patterns of pathogen genetic diversity among hosts in a population. This principle has potentially wide implications for the monitoring, modeling and management of infectious diseases. PMID:21738463

Vlak, Just M.; Zwart, Mark P.

2011-01-01

283

Apical membrane antigen 1 mediates apicomplexan parasite attachment but is dispensable for host cell invasion  

PubMed Central

Apicomplexan parasites invade host cells by forming a ring-like junction with the cell surface and actively sliding through the junction inside an intracellular vacuole. Apical membrane antigen 1 is conserved in apicomplexans and a long-standing malaria vaccine candidate. It is considered to have multiple important roles during host cell penetration, primarily in structuring the junction by interacting with the rhoptry neck 2 protein and transducing the force generated by the parasite motor during internalization. Here, we generate Plasmodium sporozoites and merozoites and Toxoplasma tachyzoites lacking apical membrane antigen 1, and find that the latter two are impaired in host cell attachment but the three display normal host cell penetration through the junction. Therefore, apical membrane antigen 1, rather than an essential invasin, is a dispensable adhesin of apicomplexan zoites. These genetic data have implications on the use of apical membrane antigen 1 or the apical membrane antigen 1rhoptry neck 2 interaction as targets of intervention strategies against malaria or other diseases caused by apicomplexans. PMID:24108241

Bargieri, Daniel Y.; Andenmatten, Nicole; Lagal, Vanessa; Thiberge, Sabine; Whitelaw, Jamie A.; Tardieux, Isabelle; Meissner, Markus; Mnard, Robert

2013-01-01

284

An updated host-parasite catalogue of world Dryinidae (Hymenoptera: Chrysidoidea).  

PubMed

An updated host-parasite catalogue of world Dryinidae is presented. The catalogue presents 1014 relationships between dryinids and their hosts checked in 84 countries of the world, including 38 new records. PMID:25112881

Guglielmino, Adalgisa; Olmi, Massimo; Bckle, Christoph

2013-01-01

285

Inflammation and oxidative stress in vertebrate hostparasite systems  

PubMed Central

Innate, inflammation-based immunity is the first line of vertebrate defence against micro-organisms. Inflammation relies on a number of cellular and molecular effectors that can strike invading pathogens very shortly after the encounter between inflammatory cells and the intruder, but in a non-specific way. Owing to this non-specific response, inflammation can generate substantial costs for the host if the inflammatory response, and the associated oxygen-based damage, get out of control. This imposes strong selection pressure that acts to optimize two key features of the inflammatory response: the timing of activation and resolution (the process of downregulation of the response). In this paper, we review the benefits and costs of inflammation-driven immunity. Our aim is to emphasize the importance of resolution of inflammation as a way of maintaining homeostasis against oxidative stress and to prevent the horror autotoxicus of chronic inflammation. Nevertheless, host immune regulation also opens the way to pathogens to subvert host defences. Therefore, quantifying inflammatory costs requires assessing (i) short-term negative effects, (ii) delayed inflammation-driven diseases, and (iii) parasitic strategies to subvert inflammation. PMID:18930878

Sorci, Gabriele; Faivre, Bruno

2008-01-01

286

Co-invaders: The effects of alien parasites on native hosts  

PubMed Central

We define co-introduced parasites as those which have been transported with an alien host to a new locality, outside of their natural range, and co-invading parasites as those which have been co-introduced and then spread to new, native hosts. Of 98 published studies of co-introductions, over 50% of hosts were freshwater fishes and 49% of parasites were helminths. Although we would expect parasites with simple, direct life cycles to be much more likely to be introduced and establish in a new locality, a substantial proportion (36%) of co-introductions were of parasites with an indirect life cycle. Seventy-eight per cent of co-introduced parasites were found in native host species and can therefore be classed as co-invaders. Host switching was equally common among parasites with direct and indirect life cycles. The magnitude of the threat posed to native species by co-invaders will depend, among other things, on parasite virulence. In 16 cases where co-introduced parasites have switched to native hosts and information was available on relative virulence, 14 (85%) were more virulent in native hosts than in the co-introduced alien host. We argue that this does not necessarily support the nave host theory that co-invading parasites will have greater pathogenic effects in native hosts with which they have no coevolutionary history, but may instead be a consequence of the greater likelihood for parasites with lower virulence in their natural host to be co-introduced. PMID:25180161

Lymbery, Alan J.; Morine, Mikayla; Kanani, Hosna Gholipour; Beatty, Stephen J.; Morgan, David L.

2014-01-01

287

The expression of virulence for a mixed-mode transmitted parasite in a diapausing host.  

PubMed

Many parasites survive harsh periods together with their hosts. Without the possibility of horizontal transmission during host diapause, parasite persistence depends entirely on host survival. We therefore hypothesize that a parasite should be avirulent during its host's diapausing stage. In contrast, the parasite may express higher virulence, i.e. parasite-induced fitness reduction of the host, during host life stages with good opportunities for horizontal transmission. Here we study the effects of a vertically and horizontally transmitted microsporidium parasite, Hamiltosporidium tvaerminnensis, on the quantity and survival of resting eggs of its host Daphnia magna. We find that the parasite did not affect egg volume, hatching success and time to hatching of the Daphnia's resting eggs, although it did strongly reduce the number of resting eggs produced by infected females, revealing high virulence during the non-diapause phase of the host's life cycle. These results also explain another aspect of this system - namely the strong decline in natural population prevalence across diapause. This decline is not caused by mortality in infected resting stages, as was previously hypothesized, but because infected female hosts produce lower rates of resting eggs. Together, these results help explain the epidemiological dynamics of a microsporidian disease and highlight the adaptive nature of life stage-dependent parasite virulence. PMID:24786012

Sheikh-Jabbari, Elham; Hall, Matthew D; Ben-Ami, Frida; Ebert, Dieter

2014-07-01

288

Are parasite intensity and related costs of the milichiid fly Carnus hemapterus related to host sociality?  

Microsoft Academic Search

Ectoparasites have often been shown to have detrimental effects on their host. Not much is known, however, about determinants\\u000a of infestation, e.g. the question of which factors affect distribution and occurrence of parasites on different host species\\u000a (degree of host specificity) and their infestation rates. In this study we examine possible effects of host determinants on\\u000a parasite intensity of Carnus

H. Hoi; J. Kritofk; A. Darolov; C. Hoi

2010-01-01

289

Expression of parasite virulence at different host population densities under natural conditions  

Microsoft Academic Search

It has recently been suggested that the expression of parasite virulence depends on host population density, such that infected\\u000a hosts have a higher sensitivity to density, and thus reach their carrying capacity earlier than uninfected hosts. In this\\u000a scenario, parasite-induced reduction in fitness (i.e., virulence) increases with host density. We tested this hypothesis experimentally,\\u000a using outdoor mesocosm populations of Daphnia

Annette Bieger; Dieter Ebert

2009-01-01

290

Temperature-dependent costs of parasitism and maintenance of polymorphism under genotype-by-environment interactions  

E-print Network

Pasteuria ramosa at 15, 20 and 25 °C. We found that the cost to the host of becoming infected varied magna; genetic variation; genotype-by-environment interaction; host­parasite; infectivity; Pasteuria ramosa; temperature; transmission; virulence evolution. Abstract The maintenance of genetic variation

Obbard, Darren

291

Individual patterns of habitat and nest-site use by hosts promote transgenerational transmission of avian brood parasitism status  

Microsoft Academic Search

Summary 1. Brood parasitic birds impose variable fitness costs upon their hosts by causing the partial or complete loss of the hosts' own brood. Growing evidence from multiple avian host-parasite taxa indicates that exposure of individual hosts to parasitism is not necessarily random and varies with habitat use, nest-site selection, age or other phenotypic attributes. For instance, nonrandom patterns of

JEFFREY P. HOOVER; MARK E. HAUBER

2007-01-01

292

Effects of rearing host species on the host-feeding capacity and parasitism of the whitefly parasitoid Encarsia formosa.  

PubMed

Parasitoids of the Encarsia genus (Hymenoptera: Aphelinidae) are important biological control agents against whiteflies. Some of the species in this genus not only parasitize their hosts, but also kill them through host feeding. The whitefly parasitoid, Encarsia formosa Gahan, was examined to determine whether the rearing host species affects its subsequent host-feeding capacity and parasitism. E. formosa wasps were reared on Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) and Bemisia tabaci (Gennadius) 'Q', and their subsequent host-feeding capacity and parasitism of T. vaporariorum and B. tabaci were examined. E. formosa reared on T. vaporariorum were significantly larger in body size than those reared on B. tabaci, but these wasps killed a similar number of whitefly nymphs by host feeding when they attacked the same host species on which they were reared. Regardless of the species on which it was reared, E. formosa fed significantly more on the B. tabaci nymphs than on the T. vaporariorum nymphs. The number of whitefly nymphs parasitized by E. formosa differed between the wasps reared on T. vaporariorum and those reared on B. tabaci depending on which whitefly species was offered as a host. In addition, the wasps reared on T. vaporariorum parasitized significantly more on T. vaporariorum than those reared on B. tabaci. The wasps reared on B. tabaci, however, parasitized similar numbers of whiteflies of both host species. The results indicated that the host-feeding capacity of E. formosa was affected more by the host species attacked than by the rearing host species, but the parasitism was affected by the host species attacked and the rearing host species. Generally, E. formosa reared on T. vaporariorum killed more T. vaporariorum nymphs by parasitism and host feeding than those reared on B. tabaci. Additionally, a similar number of B. tabaci nymphs were killed by parasitism and host feeding regardless of the rearing host species. Currently coexistence of B. tabaci and T. vaporariorum on vegetable crops usually occurs in some areas; our results may provide helpful information on using mass-reared parasitoids against mixed whitefly infestations in biological control programs. PMID:25368062

Dai, Peng; Ruan, Changchun; Zang, Liansheng; Wan, Fanghao; Liu, Linzhou

2014-01-01

293

Pathological and Ecological Host Consequences of Infection by an Introduced Fish Parasite  

PubMed Central

The infection consequences of the introduced cestode fish parasite Bothriocephalus acheilognathi were studied in a cohort of wild, young-of-the-year common carp Cyprinus carpio that lacked co-evolution with the parasite. Within the cohort, parasite prevalence was 42% and parasite burdens were up to 12% body weight. Pathological changes within the intestinal tract of parasitized carp included distension of the gut wall, epithelial compression and degeneration, pressure necrosis and varied inflammatory changes. These were most pronounced in regions containing the largest proportion of mature proglottids. Although the body lengths of parasitized and non-parasitized fish were not significantly different, parasitized fish were of lower body condition and reduced weight compared to non-parasitized conspecifics. Stable isotope analysis (?15N and ?13C) revealed trophic impacts associated with infection, particularly for ?15N where values for parasitized fish were significantly reduced as their parasite burden increased. In a controlled aquarium environment where the fish were fed ad libitum on an identical food source, there was no significant difference in values of ?15N and ?13C between parasitized and non-parasitized fish. The growth consequences remained, however, with parasitized fish growing significantly slower than non-parasitized fish, with their feeding rate (items s?1) also significantly lower. Thus, infection by an introduced parasite had multiple pathological, ecological and trophic impacts on a host with no experience of the parasite. PMID:22022606

Britton, J. Robert; Pegg, Josephine; Williams, Chris F.

2011-01-01

294

Strong specificity in the interaction between parasitoids and symbiont-protected hosts.  

PubMed

Coevolution between hosts and parasites may promote the maintenance of genetic variation in both antagonists by negative frequency-dependence if the host-parasite interaction is genotype-specific. Here we tested for specificity in the interaction between parasitoids (Lysiphlebus fabarum) and aphid hosts (Aphis fabae) that are protected by a heritable defensive endosymbiont, the ?-proteobacterium Hamiltonella defensa. Previous studies reported a lack of genotype specificity between unprotected aphids and parasitoids, but suggested that symbiont-conferred resistance might exhibit a higher degree of specificity. Indeed, in addition to ample variation in host resistance as well as parasitoid infectivity, we found a strong aphid clone-by-parasitoid line interaction on the rates of successful parasitism. This genotype specificity appears to be mediated by H.defensa, highlighting the important role that endosymbionts can play in host-parasite coevolution. PMID:22998667

Rouchet, Romain; Vorburger, C

2012-11-01

295

Microevolutionary change and population dynamics of a brood parasite and its primary host: the intermittent arms race hypothesis  

Microsoft Academic Search

A long-term study of the interactions between a brood parasite, the great spotted cuckoo Clamator glandarius, and its primary host the magpie Pica pica, demonstrated local changes in the distribution of both magpies and cuckoos and a rapid increase of rejection of both mimetic\\u000a and non-mimetic model eggs by the host. In rich areas, magpies improved three of their defensive

Manuel Soler; Juan J. Soler; Juan G. Martinez; Toms Prez-Contreras; Anders P. Mller

1998-01-01

296

Intestinal distribution and fecundity of two species of Diplostomum parasites in definitive hosts.  

PubMed

This paper investigated the intestinal distribution and fecundity of 2 species of Diplostomum parasites, D. spathaceum and D. pseudospathaceum, in 2 species of definitive hosts, herring gull (Larus argentatus) and common gull (L. canus), using both empirical field data and experimental infections. At the level of individual hosts, the parasite species occupied different parts within the intestine, but the fecundity of the worms, measured as the number of eggs in the uterus, did not differ between the parasite species except in wild common gulls. Interestingly, egg numbers in individual hosts were positively correlated between the parasite species suggesting that some birds provided better resources for the parasite species. At the host population level, fecundity of the worms did not differ between the host species or between adult birds and chicks. Both parasite species were also aggregated to the same host individuals and it is likely that aggregation is transferred to gulls from fish intermediate hosts. Individual differences in suitability and parasite numbers between hosts provide important grounds and implications for epidemiological model-based parasite prevention strategies. PMID:16318675

Karvonen, A; Cheng, G-H; Seppl, O; Valtonen, E T

2006-03-01

297

Hostile Takeover by Plasmodium: Reorganization of Parasite and Host Cell Membranes during Liver Stage  

E-print Network

Hostile Takeover by Plasmodium: Reorganization of Parasite and Host Cell Membranes during Liver, called merosomes, which are delivered directly into liver sinusoids. However, it was unclear whether by Plasmodium: Reorganization of Parasite and Host Cell Membranes during Liver Stage Egress. PLoS Pathog 7(9): e

Arnold, Jonathan

298

Evidence for gene flow in parasitic nematodes between two host species of shrews  

Microsoft Academic Search

We describe the genetic structure of populations of the intestinal nematode Longistriata caudabullata (Trichostrongyloidea: Heligmosomidae), a common parasite of short-tailed shrews (genus Blarina , Insectivora: Soricidae). Parasites and hosts were collected from a transect across a contact zone between two species of hosts, Blarina brevicauda and B. hylo- phaga, in central North America. An 800-base pairs (bp) fragment of the

Sara V. Brant; Guillermo Orti

2003-01-01

299

GEOGRAPHIC GENETIC DIFFERENTIATION OF A MALARIA PARASITE, PLASMODIUM MEXICANUM, AND ITS LIZARD HOST, SCELOPORUS OCCIDENTALIS  

E-print Network

GEOGRAPHIC GENETIC DIFFERENTIATION OF A MALARIA PARASITE, PLASMODIUM MEXICANUM, AND ITS LIZARD HOST parasite Plasmodium mexicanum, and its lizard host, Sceloporus occidentalis, at 8 sites in northern California, with the use of variable microsatellite markers for both species. These lizards are small

Schall, Joseph J.

300

Host-specificity of monogenean (platyhelminth) parasites: a role for anterior adhesive areas?  

Microsoft Academic Search

Monogeneans (flatworms) are among the most host-specific of parasites in general and may be the most host-specific of all fish parasites. Specificity, in terms of a restricted spatial distribution within an environment, is not unique to parasites and is displayed by some fungi, insects, birds, symbionts and pelagic larvae of free-living marine invertebrates. The nature of cues, how habitats are

Ian D. Whittington; Bronwen W. Cribb; Tamarind E. Hamwood; Judy A. Halliday

2000-01-01

301

Temperature-dependent costs of parasitism and maintenance of polymorphism under genotype-by-environment interactions.  

PubMed

The maintenance of genetic variation for infection-related traits is often attributed to coevolution between hosts and parasites, but it can also be maintained by environmental variation if the relative fitness of different genotypes changes with environmental variation. To gain insight into how infection-related traits are sensitive to environmental variation, we exposed a single host genotype of the freshwater crustacean Daphnia magna to four parasite isolates (which we assume to represent different genotypes) of its naturally co-occurring parasite Pasteuria ramosa at 15, 20 and 25 degrees C. We found that the cost to the host of becoming infected varied with temperature, but the magnitude of this cost did not depend on the parasite isolate. Temperature influenced parasite fitness traits; we found parasite genotype-by-environment (G x E) interactions for parasite transmission stage production, suggesting the potential for temperature variation to maintain genetic variation in this trait. Finally, we tested for temperature-dependent relationships between host and parasite fitness traits that form a key component of models of virulence evolution, and we found them to be stable across temperatures. PMID:18557795

Vale, P F; Stjernman, M; Little, T J

2008-09-01

302

A quantitative test of the relationship between parasite dose and infection probability across different hostparasite combinations  

Microsoft Academic Search

Epidemiological models generally assume that the number of susceptible individuals that become infected within a unit of time depends on the density of the hosts and the concentration of parasites (i.e. mass-action principle). However, empirical studies have found significant deviations from this assumption due to biotic and abiotic factors, such as seasonality, the spatial structure of the host population and

Frida Ben-Ami; Roland R. Regoes; Dieter Ebert

2008-01-01

303

Plant host finding by parasitic plants: a new perspective on plant to plant communication.  

PubMed

Plants release airborne chemicals that can convey ecologically relevant information to other organisms. These plant volatiles are known to mediate a large array of, often complex, interactions between plants and insects. It has been suggested that plant volatiles may have similar importance in mediating interactions among plant species, but there are few well-documented examples of plant-to-plant communication via volatiles, and the ecological significance of such interactions has been much debated. To date, nearly all studies of volatile-mediated interactions among plant species have focused on the reception of herbivore-induced volatiles by neighboring plants. We recently documented volatile effects in another system, demonstrating that the parasitic plant Cuscuta pentagona uses volatile cues to locate its hosts. This finding may broaden the discussion regarding plant-to-plant communication, and suggests that new classes of volatile-meditated interactions among plant species await discovery. PMID:19704627

Mescher, Mark C; Runyon, Justin B; De Moraes, Consuelo M

2006-11-01

304

Host cell deformability is linked to transmission in the human malaria parasite Plasmodium falciparum  

PubMed Central

SUMMARY Gametocyte maturation in Plasmodium falciparum is a critical step in the transmission of malaria. While the majority of parasites proliferate asexually in red blood cells, a small fraction of parasites undergo sexual conversion and mature over two weeks to become competent for transmission to a mosquito vector. Immature gametocytes sequester in deep tissues while mature stages must be able to circulate, pass the spleen and present themselves to the mosquito vector in order to complete transmission. Sequestration of asexual red blood cell stage parasites has been investigated in great detail. These studies have demonstrated that induction of cytoadherence properties through specific receptor-ligand interactions coincides with a significant increase in host cell stiffness. In contrast, the adherence and biophysical properties of gametocyte-infected red blood cells have not been studied systematically. Utilizing a transgenic line for 3D live imaging, in vitro capillary assays and 3D finite element whole cell modeling, we studied the role of cellular deformability in determining the circulatory characteristics of gametocytes. Our analysis shows that the red blood cell deformability of immature gametocytes displays an overall decrease followed by rapid restoration in mature gametocytes. Intriguingly, simulations suggest that along with deformability variations, the morphological changes of the parasite may play an important role in tissue distribution in vivo. Taken together we present a model, which suggests that mature but not immature gametocytes circulate in the peripheral blood for uptake in the mosquito blood meal and transmission to another human host thus ensuring long term survival of the parasite. PMID:22417683

Aingaran, Mythili; Zhang, Rou; Law, Sue KaYee; Peng, Zhangli; Undisz, Andreas; Meyer, Evan; Diez-Silva, Monica; Burke, Thomas A.; Spielmann, Tobias; Lim, Chwee Teck; Suresh, Subra; Dao, Ming; Marti, Matthias

2012-01-01

305

Alternative mechanisms of increased eggshell hardness of avian brood parasites relative to host species  

PubMed Central

Obligate brood parasitic birds lay their eggs in nests of other species and parasite eggs typically have evolved greater structural strength relative to host eggs. Increased mechanical strength of the parasite eggshell is an adaptation that can interfere with puncture ejection behaviours of discriminating hosts. We investigated whether hardness of eggshells is related to differences between physical and chemical traits from three different races of the parasitic common cuckoo Cuculus canorus, and their respective hosts. Using tools developed for materials science, we discovered a novel correlate of increased strength of parasite eggs: the common cuckoo's egg exhibits a greater microhardness, especially in the inner region of the shell matrix, relative to its host and sympatric non-host species. We then tested predictions of four potential mechanisms of shell strength: (i) increased relative thickness overall, (ii) greater proportion of the structurally harder shell layers, (iii) higher concentration of inorganic components in the shell matrix, and (iv) elevated deposition of a high density compound, MgCO3, in the shell matrix. We confirmed support only for hypothesis (i). Eggshell characteristics did not differ between parasite eggs sampled from different host nests in distant geographical sites, suggesting an evolutionarily shared microstructural mechanism of stronger parasite eggshells across diverse host-races of brood parasitic cuckoos. PMID:21561966

Igic, Branislav; Braganza, Kim; Hyland, Margaret M.; Silyn-Roberts, Heather; Cassey, Phillip; Grim, Tomas; Rutila, Jarkko; Moskt, Csaba; Hauber, Mark E.

2011-01-01

306

Food stoichiometry affects the outcome of Daphniaparasite interaction  

PubMed Central

Phosphorus (P) is an essential nutrient for growth in consumers. P-limitation and parasite infection comprise one of the most common stressor pairs consumers confront in nature. We conducted a life-table study using a Daphniamicrosporidian parasite model, feeding uninfected or infected Daphnia with either P-sufficient or P-limited algae, and assessed the impact of the two stressors on life-history traits of the host. Both infection and P-limitation negatively affected some life-history traits tested. However, under P-limitation, infected animals had higher juvenile growth rate as compared with uninfected animals. All P-limited individuals died before maturation, regardless of infection. The numbers of spore clusters of the microsporidian parasite did not differ in P-limited or P-sufficient hosts. P-limitation, but not infection, decreased body phosphorus content and ingestion rates of Daphnia tested in separate experiments. As parasite spore production did not suffer even under extreme P-limitation, our results suggest that parasite was less limited by P than the host. We discuss possible interpretations concerning the stoichiometrical demands of parasite and suggest that our results are explained by parasite-driven changes in carbon (C) allocation of the hosts. We conclude that the impact of nutrient starvation and parasite infection on consumers depends not only on the stoichiometric demands of host but also those of the parasite. PMID:23762513

Aalto, Sanni L; Pulkkinen, Katja

2013-01-01

307

Expressed sequence tags from Amoebophrya sp. infecting Karlodinium veneficum: comparing host and parasite sequences.  

PubMed

Parasitic dinoflagellates of the genus Amoebophrya play important roles in the ecology of estuaries and open ocean environments. Little is known of the cell and molecular biology of Amoebophrya, but the genus is intermediate on phylogenetic trees between apicomplexans and typical dinophycean dinoflagellates. Here, we constructed four cDNA libraries, from different stages after infecting the host, Karlodinium veneficum, with Amoebophrya sp. These libraries were used to generate 898 expressed sequence tags (ESTs), with sequences attributed to either the host or parasite, based on AT bias, codon usage, and occurrence during infection. Overall, 209 sequences were attributable to the parasite and 685 to the host. The 50 putative parasite sequences with good protein matches in GenBank were used to find the same protein from host ESTs. For 26 genes, both host and parasite sequences were identified, of which 20 encoded ribosomal proteins. PCR for seven predicted parasite and two host genes were used to confirm attributions. The most common host and parasite ESTs were compared to see if multiple gene copies were present. The host plastocyanin gene had multiple sequence variants, but parasite rps27a contained only one polymorphism, likely due to an amplification error. Amplification, cloning, and sequencing of five parasite protein-coding genes suggested that the parasite has a single sequence for each gene, but three host genes were found to have multiple variants. The genome of Amoebophrya sp. infecting K. veneficum appears to have an organization more similar to other eukaryotes than to the tandem gene arrangements found in dinoflagellates. PMID:19883441

Bachvaroff, Tsvetan R; Place, Allen R; Coats, Donald Wayne

2009-01-01

308

Plant science. Genomic-scale exchange of mRNA between a parasitic plant and its hosts.  

PubMed

Movement of RNAs between cells of a single plant is well documented, but cross-species RNA transfer is largely unexplored. Cuscuta pentagona (dodder) is a parasitic plant that forms symplastic connections with its hosts and takes up host messenger RNAs (mRNAs). We sequenced transcriptomes of Cuscuta growing on Arabidopsis and tomato hosts to characterize mRNA transfer between species and found that mRNAs move in high numbers and in a bidirectional manner. The mobile transcripts represented thousands of different genes, and nearly half the expressed transcriptome of Arabidopsis was identified in Cuscuta. These findings demonstrate that parasitic plants can exchange large proportions of their transcriptomes with hosts, providing potential mechanisms for RNA-based interactions between species and horizontal gene transfer. PMID:25124438

Kim, Gunjune; LeBlanc, Megan L; Wafula, Eric K; dePamphilis, Claude W; Westwood, James H

2014-08-15

309

INFLUENCE OF ALTERNATE HOST DENSITIES ON BROWN-HEADED COWBIRD PARASITISM RATES IN BLACK-CAPPED VIREOS  

Microsoft Academic Search

Brown-headed Cowbird (Molothrus ater) parasitism is thought to be partly influenced by density of the host species, although tests of host density are relatively rare. We examined parasitism rates relative to the density of individual host species and densities of coexisting host species. We monitored 392 nests among coexisting host species and measured their densities among six habitats on Fort

DAVID R. BARBER; THOMAS E. MARTINS

310

Parasite maturation and host serum iron influence the labile iron pool of erythrocyte stage Plasmodium falciparum.  

PubMed

Iron is a critical and tightly regulated nutrient for both the malaria parasite and its human host. The importance of the relationship between host iron and the parasite has been underscored recently by studies showing that host iron supplementation may increase the risk of falciparum malaria. It is unclear what host iron sources the parasite is able to access. We developed a flow cytometry-based method for measuring the labile iron pool (LIP) of parasitized erythrocytes using the nucleic acid dye STYO 61 and the iron sensitive dye, calcein acetoxymethyl ester (CA-AM). This new approach enabled us to measure the LIP of P.falciparum through the course of its erythrocytic life cycle and in response to the addition of host serum iron sources. We found that the LIP increases as the malaria parasite develops from early ring to late schizont stage, and that the addition of either transferrin or ferric citrate to culture media increases the LIP of trophozoites. Our method for detecting the LIP within malaria parasitized RBCs provides evidence that the parasite is able to access serum iron sources as part of the host vs. parasite arms race for iron. PMID:23398516

Clark, Martha; Fisher, Nancy C; Kasthuri, Raj; Cerami Hand, Carla

2013-04-01

311

Hostparasite coevolution beyond the nestling stage? Mimicry of host fledglings by the specialist screaming cowbird  

PubMed Central

Egg mimicry by obligate avian brood parasites and host rejection of non-mimetic eggs are well-known textbook examples of hostparasite coevolution. By contrast, reciprocal adaptations and counteradaptations beyond the egg stage in brood parasites and their hosts have received less attention. The screaming cowbird (Molothrus rufoaxillaris) is a specialist obligate brood parasite whose fledglings look identical to those of its primary host, the baywing (Agelaioides badius). Such a resemblance has been proposed as an adaptation in response to host discrimination against odd-looking young, but evidence supporting this idea is scarce. Here, we examined this hypothesis by comparing the survival rates of young screaming cowbirds and non-mimetic shiny cowbirds (Molothrus bonariensis) cross-fostered to baywing nests and quantifying the similarity in plumage colour and begging calls between host and cowbird fledglings. Shiny cowbirds suffered higher post-fledging mortality rates (83%) than screaming cowbirds (0%) owing to host rejection. Visual modelling revealed that screaming cowbirds, but not shiny cowbirds, were indistinguishable from host young in plumage colour. Similarly, screaming cowbirds matched baywings' begging calls more closely than shiny cowbirds. Our results strongly support the occurrence of host fledgling mimicry in screaming cowbirds and suggest a role of visual and vocal cues in fledgling discrimination by baywings. PMID:22648157

De Mrsico, Mara C.; Gantchoff, Mariela G.; Reboreda, Juan C.

2012-01-01

312

Relic behaviours, coevolution and the retention versus loss of host defences after episodes of avian brood parasitism  

Microsoft Academic Search

Most previous studies of brood parasitism have stressed that host defences, such as egg recognition, are lost in the absence of parasitism. Such losses could result in coevolutionary cycles in which parasites shift away from well-defended hosts only to switch back to them later at a time when these hosts have lost much or all of their defences and the

Stephen I. Rothstein

2001-01-01

313

Host specificity shapes population structure of pinworm parasites in Caribbean reptiles.  

PubMed

Host specificity is one of the potential factors affecting parasite diversification because gene flow may be facilitated or constrained by the number of host species that a parasite can exploit. We test this hypothesis using a costructure approach, comparing two sympatric pinworm parasites that differ in host specificity - Parapharyngodon cubensis and Spauligodon anolis - on the Puerto Rican Bank and St. Croix in the Caribbean. Spauligodon anolis specializes on Anolis lizards, whereas P.cubensis parasitizes Anolis lizards as well as many other species of lizards and snakes. We collected lizards from across the Puerto Rican Bank and St. Croix, sampled them for S.anolis and P.cubensis and generated nuclear and mitochondrial sequence data from the parasites. We used these data to show that P.cubensis is comprised of multiple cryptic species that exhibit limited population structure relative to S.anolis, which is consistent with our prediction based on their host specificity. We also provide evidence that the distribution of P.cubensis species is maintained by competitive exclusion, and in contrast to previous theoretical work, the parasites with the greatest number of host species also reach the highest prevalence rates. Overall, our results are consistent with the hypothesis that host specificity shapes parasite diversification, and suggest that even moderate differences in host specificity may contribute to substantial differences in diversification. PMID:23848187

Falk, Bryan G; Perkins, Susan L

2013-09-01

314

Chronology of parasite-induced alteration of fish behaviour: effects of parasite maturation and host experience  

E-print Network

Chronology of parasite-induced alteration of fish behaviour: effects of parasite maturation (Ornithodiplostomum ptychocheilus). This parasite develops and then encysts in a region of the brain that mediates experienced the drum. Because maximum parasite- induced reduction in OMR coincided with the period of maximum

Wisenden, Brian D.

315

Current opinions: Zeros in hostparasite food webs: Are they real??  

PubMed Central

As the data have poured in, and the number of published food webs containing parasites has increased, questions have been raised as to why free-living species consistently outnumber parasites, even though most general reviews on the subject of host:parasite species richness suggest the contrary. Here, I describe this pattern as it exists in the literature, posit both real and artifactual sources of these findings, and suggest ways that we might interpret existing parasite-inclusive food webs. In large part, the reporting of free-living species devoid of any associated parasites (termed here in the coding of food web matrices as zeros) is a consequence of either sampling issues or the intent of the study. However, there are also several powerful explanatory features that validate real cases of this phenomenon. Some hosts appear to authentically lack parasitism in portions of their geographic ranges, and parasites are often lost from systems that are either in early phases of community re-colonization or are compromised by environmental perturbation. Additionally, multi-stage parasite life cycles and broad host spectra allow some parasite species to partially saturate systems without providing a corresponding increase in parasite species richness, leading to low parasite species richness values relative to the free-living community. On the whole, the existing published food webs are sufficient to, at least in principle, determine basic patterns and pathways associated with parasite establishment and persistence in free-living communities because (1) for the purpose of those features, species rarity is roughly analogous to absence and (2) the existing data seem to suggest that the addition of more parasite taxa would reinforce the patterns already observed. This is particularly true for helminth parasites, in which our understanding and the resolution of our work is most robust. PMID:24533341

Rossiter, Wayne

2013-01-01

316

Pasteuria penetrans and Its Parasitic Interaction with Plant Parasitic Nematodes  

Microsoft Academic Search

\\u000a The genus Pasteuria comprises a truly extraordinary group of unculturable bacteria that are obligate parasites of either water fleas or plant\\u000a parasitic nematodes. They have an astonishing vegetative morphology that, through an intricate process of differentiation,\\u000a leads to a structurally unique endospore form. Remarkably, phylogenetic studies indicate that this genus is ancestral to the\\u000a genus Bacillus. P.\\u000a penetrans is the

Alistair H. Bishop

317

How to evade a coevolving brood parasite: egg discrimination versus egg variability as host defences  

PubMed Central

Arms races between avian brood parasites and their hosts often result in parasitic mimicry of host eggs, to evade rejection. Once egg mimicry has evolved, host defences could escalate in two ways: (i) hosts could improve their level of egg discrimination; and (ii) negative frequency-dependent selection could generate increased variation in egg appearance (polymorphism) among individuals. Proficiency in one defence might reduce selection on the other, while a combination of the two should enable successful rejection of parasitic eggs. We compared three highly variable host species of the Afrotropical cuckoo finch Anomalospiza imberbis, using egg rejection experiments and modelling of avian colour and pattern vision. We show that each differed in their level of polymorphism, in the visual cues they used to reject foreign eggs, and in their degree of discrimination. The most polymorphic host had the crudest discrimination, whereas the least polymorphic was most discriminating. The third species, not currently parasitized, was intermediate for both defences. A model simulating parasitic laying and host rejection behaviour based on the field experiments showed that the two host strategies result in approximately the same fitness advantage to hosts. Thus, neither strategy is superior, but rather they reflect alternative potential evolutionary trajectories. PMID:21490019

Spottiswoode, Claire N.; Stevens, Martin

2011-01-01

318

Parasitic aphrodisiacs: manipulation of the hosts' behavioral defenses by sexually transmitted parasites.  

PubMed

Animals have a number of behavioral defenses against infection. For example, they typically avoid sick conspecifics, especially during mating. Most animals also alter their behavior after infection and thereby promote recovery (i.e., sickness behavior). For example, sick animals typically reduce the performance of energetically demanding behaviors, such as sexual behavior. Finally, some animals can increase their reproductive output when they face a life-threatening immune challenge (i.e., terminal reproductive investment). All of these behavioral responses probably rely on immune/neural communication signals for their initiation. Unfortunately, this communication channel is prone to manipulation by parasites. In the case of sexually transmitted infections (STIs), these parasites/pathogens must subvert some of these behavioral defenses for successful transmission. There is evidence that STIs suppress systemic signals of immune activation (e.g., pro-inflammatory cytokines). This manipulation is probably important for the suppression of sickness behavior and other behavioral defenses, as well as for the prevention of attack by the host's immune system. For example, the cricket, Gryllus texensis, is infected with an STI, the iridovirus IIV-6/CrIV. The virus attacks the immune system, which suffers a dramatic decline in its ability to make proteins important for immune function. This attack also hampers the ability of the immune system to activate sickness behavior. Infected crickets cannot express sickness behavior, even when challenged with heat-killed bacteria. Understanding how STIs suppress sickness behavior in humans and other animals will significantly advance the field of psychoneuroimmunology and could also provide practical benefits. PMID:24813461

Adamo, Shelley A

2014-07-01

319

Mixed-host aggregations and helminth parasite sharing in an East African wildlife-livestock system.  

PubMed

Parasitic infections transmitted between livestock and wildlife pose a significant risk to wildlife conservation efforts and constrain livestock productivity in tropical regions of the world. Gastrointestinal helminths are among the most ubiquitous parasites, and many parasites within this taxon can readily infect a wide range of host species. Factors shaping bidirectional transmission of parasites in wildlife-livestock systems are understudied. In this study, we investigate the prevalence and diversity of helminth infections in an East African community of wild and domestic ungulates. We also identify pairs of host species between which transmission may be possible based on shared parasite taxa, and explore the role of multi-host aggregations in shaping patterns of parasite sharing. Helminth taxa detected included Trichostrongylus, Trichuris, Paramphistomum, Skrjabinema, Strongyloides, Strongylus spp., and other strongyle-type nematodes. We found that nearly 50% of individuals harbored at least one species of helminth, but certain species, such as zebra and impala, exhibited higher prevalence than others. High canopy feeders, like giraffe, had lower prevalence than hosts feeding at medium and low foraging heights. For helminths, patterns of parasite sharing likely emerge from shared space use, which is mediated in part by mixed-species aggregations. The frequency with which host species associated together in mixed-species aggregations was positively correlated with the number of parasite taxa shared. We suggest that variation among species in their tendency to form mixed-species aggregations creates heterogeneity in transmission opportunities, and consequently, parasite sharing across ungulate species. These results enhance our understanding of the role of spatiotemporal relationships among host species in shaping parasite communities in mixed wildlife-livestock grazing systems. PMID:25086496

VanderWaal, Kimberly; Omondi, George Paul; Obanda, Vincent

2014-09-15

320

Bot fly parasitism of the red-backed vole: host survival, infection risk, and population growth  

Microsoft Academic Search

Parasites can play an important role in the dynamics of host populations, but empirical evidence remains sparse. We investigated\\u000a the role of bot fly (Cuterebra spp.) parasitism in red-backed voles (Myodes gapperi) by first assessing the impacts of the parasite on the probability of vole survival under stressful conditions as well as\\u000a on the reproductive activity of females. We then

Jrme Lematre; Daniel Fortin; Pierre-Olivier Montiglio; Marcel Darveau

2009-01-01

321

The 8D05 parasitism gene of Meloidogyne incognita is required for successful infection of host roots.  

PubMed

Parasitism genes encode effector proteins that are secreted through the stylet of root-knot nematodes to dramatically modify selected plant cells into giant-cells for feeding. The Mi8D05 parasitism gene previously identified was confirmed to encode a novel protein of 382 amino acids that had only one database homolog identified on contig 2374 within the Meloidogyne hapla genome. Mi8D05 expression peaked in M. incognita parasitic second-stage juveniles within host roots and its encoded protein was limited to the subventral esophageal gland cells that produce proteins secreted from the stylet. Constitutive expression of Mi8D05 in transformed Arabidopsis thaliana plants induced accelerated shoot growth and early flowering but had no visible effects on root growth. Independent lines of transgenic Arabidopsis that expressed a double-stranded RNA complementary to Mi8D05 in host-derived RNA interference (RNAi) tests had up to 90% reduction in infection by M. incognita compared with wild-type control plants, suggesting that Mi8D05 plays a critical role in parasitism by the root-knot nematode. Yeast two-hybrid experiments confirmed the specific interaction of the Mi8D05 protein with plant aquaporin tonoplast intrinsic protein 2 (TIP2) and provided evidence that the Mi8D05 effector may help regulate solute and water transport within giant-cells to promote the parasitic interaction. PMID:23294405

Xue, Bingye; Hamamouch, Noureddine; Li, Chunying; Huang, Guozhong; Hussey, Richard S; Baum, Thomas J; Davis, Eric L

2013-02-01

322

From pathogen genomes to host plant processes: the power of plant parasitic oomycetes  

PubMed Central

Recent pathogenomic research on plant parasitic oomycete effector function and plant host responses has resulted in major conceptual advances in plant pathology, which has been possible thanks to the availability of genome sequences. PMID:23809564

2013-01-01

323

Like herbivores, parasitic plants are limited by host nitrogen Steven C. Pennings Juliet C. Simpson  

E-print Network

and of the holoparasite Cuscuta salina (dodder) increased in fertilized plots in both micro- habitats. Cuscuta preferred to increases in host nitrogen status. Keywords Cuscuta Á Fertilization experiment Á Nitrogen Á Parasitic plant

Pennings, Steven C.

324

Babesia divergens and Neospora caninum apical membrane antigen 1 structures reveal selectivity and plasticity in apicomplexan parasite host cell invasion  

PubMed Central

Host cell invasion by the obligate intracellular apicomplexan parasites, including Plasmodium (malaria) and Toxoplasma (toxoplasmosis), requires a step-wise mechanism unique among known hostpathogen interactions. A key step is the formation of the moving junction (MJ) complex, a circumferential constriction between the apical tip of the parasite and the host cell membrane that traverses in a posterior direction to enclose the parasite in a protective vacuole essential for intracellular survival. The leading model of MJ assembly proposes that Rhoptry Neck Protein 2 (RON2) is secreted into the host cell and integrated into the membrane where it serves as the receptor for apical membrane antigen 1 (AMA1) on the parasite surface. We have previously demonstrated that the AMA1-RON2 interaction is an effective target for inhibiting apicomplexan invasion. To better understand the AMA1-dependant molecular recognition events that promote invasion, including the significant AMA1-RON2 interaction, we present the structural characterization of AMA1 from the apicomplexan parasites Babesia divergens (BdAMA1) and Neospora caninum (NcAMA1) by X-ray crystallography. These studies offer intriguing structural insight into the RON2-binding surface groove in the AMA1 apical domain, which shows clear evidence for receptorligand co-evolution, and the hyper variability of the membrane proximal domain, which in Plasmodium is responsible for direct binding to erythrocytes. By incorporating the structural analysis of BdAMA1 and NcAMA1 with existing AMA1 structures and complexes we were able to define conserved pockets in the AMA1 apical groove that could be targeted for the design of broadly reactive therapeutics. PMID:23169033

Tonkin, Michelle L; Crawford, Joanna; Lebrun, Maryse L; Boulanger, Martin J

2013-01-01

325

The energetic grooming costs imposed by a parasitic mite (Spinturnix myoti) upon its bat host  

E-print Network

The energetic grooming costs imposed by a parasitic mite (Spinturnix myoti) upon its bat host¤cient at reducing parasitic loads in both birds and mammals, but the energetic costs it entails have not been properly quanti¢ed. We measured both the energetic metabolism and behaviour of greater mouse-eared bats

Richner, Heinz

326

COMPLEX HOST-PARASITE SYSTEMS IN MARTES: IMPLICATIONS FOR CONSERVATION BIOLOGY OF ENDEMIC FAUNAS.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Complex assemblages of hosts and parasites reveal insights about biogeography and ecology and inform us about processes which serve to structure faunal diversity and the biosphere in space and time. Exploring aspects of parasite diversity among martens (species of Martes) and other mustelids reveal...

327

Human land use and patterns of parasitism in tropical amphibian hosts  

E-print Network

Human land use and patterns of parasitism in tropical amphibian hosts Valerie J. Mc: Amphibian Parasite Land use Tropics Forest Pasture A B S T R A C T Landscape alterations by humans can amphibians was associated with land use change, I studied three species of amphibians, Rana vaillanti

McKenzie, Valerie

328

The review of "The Oestrid Flies: Biology, host-parasite relationships, impact and management"  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Oestrid flies are a diverse group of parasitic insects whose larval forms are adapted for a parasitic life-style. Their armament of spines and mouth hooks, enables their migration within host tissues and provides for beastly images as depicted on the front cover of the book and within the text....

329

Killing of Trypanosomatid Parasites by a Modified Bovine Host Defense Peptide, BMAP-18  

Microsoft Academic Search

BackgroundTropical diseases caused by parasites continue to cause socioeconomic devastation that reverberates worldwide. There is a growing need for new control measures for many of these diseases due to increasing drug resistance exhibited by the parasites and problems with drug toxicity. One new approach is to apply host defense peptides (HDP; formerly called antimicrobial peptides) to disease control, either to

Lee R. Haines; Jamie M. Thomas; Angela M. Jackson; Brett A. Eyford; Morteza Razavi; Cristalle N. Watson; Brent Gowen; Robert E. W. Hancock; Terry W. Pearson

2009-01-01

330

Host response to cuckoo song is predicted by the future risk of brood parasitism  

PubMed Central

Introduction Risk assessment occurs over different temporal and spatial scales and is selected for when individuals show an adaptive response to a threat. Here, we test if birds respond to the threat of brood parasitism using the acoustical cues of brood parasites in the absence of visual stimuli. We broadcast the playback of song of three brood parasites (Chalcites cuckoo species) and a sympatric non-parasite (striated thornbill, Acanthiza lineata) in the territories of superb fairy-wrens (Malurus cyaneus) during the peak breeding period and opportunistic breeding period. The three cuckoo species differ in brood parasite prevalence and the probability of detection by the host, which we used to rank the risk of parasitism (high risk, moderate risk, low risk). Results Host birds showed the strongest response to the threat of cuckoo parasitism in accordance with the risk of parasitism. Resident wrens had many alarm calls and close and rapid approach to the playback speaker that was broadcasting song of the high risk brood parasite (Horsfields bronze-cuckoo, C. basalis) across the year (peak and opportunistic breeding period), some response to the moderate risk brood parasite (shining bronze-cuckoo, C. lucidus) during the peak breeding period, and the weakest response to the low risk brood parasite (little bronze-cuckoo, C. minutillus). Playback of the familiar control stimulus in wren territories evoked the least response. Conclusion Host response to the threat of cuckoo parasitism was assessed using vocal cues of the cuckoo and was predicted by the risk of future parasitism. PMID:23692969

2013-01-01

331

MicrobeHost Interactions are Positively and Negatively Regulated by GalectinGlycan Interactions  

PubMed Central

Microbehost interactions are complex processes that are directly and indirectly regulated by a variety of factors, including microbe presentation of specific molecular signatures on the microbial surface, as well as host cell presentation of receptors that recognize these pathogen signatures. Cell surface glycans are one important class of microbial signatures that are recognized by a variety of host cell lectins. Host cell lectins that recognize microbial glycans include members of the galectin family of lectins that recognize specific glycan ligands on viruses, bacteria, fungi, and parasites. In this review, we will discuss the ways that the interactions of microbial glycans with host cell galectins positively and negatively regulate pathogen attachment, invasion, and survival, as well as regulate host responses that mitigate microbial pathogenesis. PMID:24995007

Baum, Linda G.; Garner, Omai B.; Schaefer, Katrin; Lee, Benhur

2014-01-01

332

Visual modeling shows that avian host parents use multiple visual cues in rejecting parasitic eggs  

PubMed Central

One of the most striking outcomes of coevolution between species is egg mimicry by brood parasitic birds, resulting from rejection behavior by discriminating host parents. Yet, how exactly does a host detect a parasitic egg? Brood parasitism and egg rejection behavior provide a model system for exploring the relative importance of different visual cues used in a behavioral task. Although hosts are discriminating, we do not know exactly what cues they use, and to answer this it is crucial to account for the receiver's visual perception. Color, luminance (perceived lightness) and pattern information have never been simultaneously quantified and experimentally tested through a bird's eye. The cuckoo finch Anomalospiza imberbis and its hosts show spectacular polymorphisms in egg appearance, providing a good opportunity for investigating visual discrimination owing to the large range of patterns and colors involved. Here we combine field experiments in Africa with modeling of avian color vision and pattern discrimination to identify the specific visual cues used by hosts in making rejection decisions. We found that disparity between host and foreign eggs in both color and several aspects of pattern (dispersion, principal marking size, and variability in marking size) were important predictors of rejection, especially color. These cues correspond exactly to the principal differences between host and parasitic eggs, showing that hosts use the most reliable available cues in making rejection decisions, and select for parasitic eggs that are increasingly mimetic in a range of visual attributes. PMID:20421497

Spottiswoode, Claire N.; Stevens, Martin

2010-01-01

333

Using parasites to infer host population history: a new rationale for parasite conservation  

Microsoft Academic Search

Only one of the 5000 extant louse species (Phthiraptera) and no species of flea (Siphonaptera), parasitic helminth (Platyhelminthes), parasitic nematode (Nemata), mite, or tick (Acari) is listed as threatened by the IUCN, despite impassioned pleas for parasite conservation beginning more than a decade ago. Although they should be conserved for their own sake, past arguments, highlighting the intrinsic and utilitarian

Noah Kerness Whiteman; Patricia G. Parker

2005-01-01

334

Exploring the Host Parasitism of the Migratory Plant-Parasitic Nematode Ditylenchus destuctor by Expressed Sequence Tags Analysis  

PubMed Central

The potato rot nematode, Ditylenchus destructor, is a very destructive nematode pest on many agriculturally important crops worldwide, but the molecular characterization of its parasitism of plant has been limited. The effectors involved in nematode parasitism of plant for several sedentary endo-parasitic nematodes such as Heterodera glycines, Globodera rostochiensis and Meloidogyne incognita have been identified and extensively studied over the past two decades. Ditylenchus destructor, as a migratory plant parasitic nematode, has different feeding behavior, life cycle and host response. Comparing the transcriptome and parasitome among different types of plant-parasitic nematodes is the way to understand more fully the parasitic mechanism of plant nematodes. We undertook the approach of sequencing expressed sequence tags (ESTs) derived from a mixed stage cDNA library of D. destructor. This is the first study of D. destructor ESTs. A total of 9800 ESTs were grouped into 5008 clusters including 3606 singletons and 1402 multi-member contigs, representing a catalog of D. destructor genes. Implementing a bioinformatics' workflow, we found 1391 clusters have no match in the available gene database; 31 clusters only have similarities to genes identified from D. africanus, the most closely related species to D. destructor; 1991 clusters were annotated using Gene Ontology (GO); 1550 clusters were assigned enzyme commission (EC) numbers; and 1211 clusters were mapped to 181 KEGG biochemical pathways. 22 ESTs had similarities to reported nematode effectors. Interestedly, most of the effectors identified in this study are involved in host cell wall degradation or modification, such as 1,4-beta-glucanse, 1,3-beta-glucanse, pectate lyase, chitinases and expansin, or host defense suppression such as calreticulin, annexin and venom allergen-like protein. This result implies that the migratory plant-parasitic nematode D. destructor secrets similar effectors to those of sedentary plant nematodes. Finally we further characterized the two D. destructor expansin proteins. PMID:23922743

Peng, Huan; Gao, Bing-li; Kong, Ling-an; Yu, Qing; Huang, Wen-kun; He, Xu-feng; Long, Hai-bo; Peng, De-liang

2013-01-01

335

The importance of gobies (Gobiidae, Teleostei) as hosts and transmitters of parasites in the SW Baltic  

NASA Astrophysics Data System (ADS)

The parasite fauna of five goby species (Gobiidae, Teleostei) was investigated in the Baltic Sea during the period 1987 to 1990. 13 parasite species were found in samples from the Lbeck Bight: Bothriocephalus scorpii, Schistocephalus sp. (Cestoda); Cryptocotyle concavum, Cryptocotyle lingua, Podocotyle atomon, Derogenes varicus (Digenea); Hysterothylacium sp. (cf. auctum), Contracaecum sp., Anisakis simplex (Nematoda); Corynosoma sp., Echinorhynchus gadi, Neoechinorhynchus rutili, Pomphorhynchus laevis (Acanthocephala). The number of parasite species were: 10 in the sand goby Pomatoschistus minutus, 8 in the black goby Gobius niger, 7 in the two-spotted goby Gobiusculus flavescens, 6 in the common goby Pomatoschistus microps, and 5 in the painted goby Pomatoschistus pictus. Neoechinorhynchus rutili occurred only in P. minutus, and Corynosoma sp. only in G. niger. The extent to which the gobies were parasitized clearly depended on the respective ways of life and, moreover, on the kind of prey ingested by the hosts. Additionally, the age of the hosts might be important. The highest rate of parasitism, more than 60%, was reached by Hysterothylacium sp. in G. niger and by Cryptocotyle concavum in P. microps. Infestation incidence lay mostly below 40% which means a satellite species status (Holmes, 1991). The number of parasite species was highest in summer; the highest intensities of single parasites occurred in spring ( Podocotyle atomon) or autumn ( Crytocotyle concavum). Bothriocephalus scorpii, Hysterothylacium sp. and Podocotyle infested their juvenile hosts very early, but only Hysterothylacium was accumulated by G. niger during its whole life span, whereas Bothriocephalus persisted also in older gobies in low intensities. The cercariae of Cryptocotyle spp. penetrate actively into their hosts; all the other parasites named were transmitted in larval form by prey organisms which consisted mainly of planktonic and benthic crustaceans. The gobies were final hosts for only 5 parasites; but two species may be transmitted to larger fish, and 6 species to sea birds or mammals. The parasite community of the five gobies may possibly be taken to characterize the ecological quality of the environment of the Lbeck Bight.

Zander, C. D.; Strohbach, U.; Groenewold, S.

1993-02-01

336

Differential sources of host species heterogeneity influence the transmission and control of multihost parasites  

PubMed Central

Controlling parasites that infect multiple host species often requires targeting single species that dominate transmission. Yet, it is rarely recognised that such key hosts can arise through disparate mechanisms, potentially requiring different approaches for control. We identify three distinct, but not mutually exclusive, processes that underlie host species heterogeneity: infection prevalence, population abundance and infectiousness. We construct a theoretical framework to isolate the role of each process from ecological data and to explore the outcome of different control approaches. Applying this framework to data on 11 gastrointestinal parasites in small mammal communities across the eastern United States reveals variation not only in the magnitude of transmission asymmetries among host species but also in the processes driving heterogeneity. These differences influence the efficiency by which different control strategies reduce transmission. Identifying and tailoring interventions to a specific type of key host may therefore enable more effective management of multihost parasites. PMID:23714379

Streicker, Daniel G; Fenton, Andy; Pedersen, Amy B

2013-01-01

337

Supporting Information 3. Host-parasite simulations Deterministic computer simulations were performed to evaluate the effect of maternally-  

E-print Network

Supporting Information 3. Host-parasite simulations Deterministic computer simulations were performed to evaluate the effect of maternally- transmitted parasites on the evolution of sex. Briefly, the simulations work as follows. Hosts are assumed to be diploid and parasites to be haploid. Both species have

Agrawal, Aneil F.

338

Ecomorphology and disease: cryptic effects of parasitism on host habitat use, thermoregulation, and predator avoidance.  

PubMed

Parasites can cause dramatic changes in the phenotypes of their hosts, sometimes leading to a higher probability of predation and parasite transmission. Because an organism's morphology directly affects its locomotion, even subtle changes in key morphological traits may affect survival and behavior. However, despite the ubiquity of parasites in natural communities, few studies have incorporated parasites into ecomorphological research. Here, we evaluated the effects of parasite-induced changes in host phenotype on the habitat use, thermal biology, and simulated predator-escape ability of Pacific chorus frogs (Pseudacris regilla) in natural environments. Frogs with parasite-induced limb malformations were more likely to use ground microhabitats relative to vertical refugia and selected less-angled perches closer to the ground in comparison with normal frogs. Although both groups had similar levels of infection, malformed frogs used warmer microhabitats, which resulted in higher body temperatures. Likely as a result of their morphological abnormalities, malformed frogs allowed a simulated predator to approach closer before escaping and escaped shorter distances relative to normal frogs. These data indicate that parasite-induced morphological changes can significantly alter host behavior and habitat use, highlighting the importance of incorporating the ubiquitous, albeit cryptic, role of parasites into ecomorphological research. PMID:21608461

Goodman, Brett A; Johnson, Pieter T J

2011-03-01

339

First study on parasites of Hemibrycon surinamensis (Characidae), a host from the eastern Amazon region.  

PubMed

This study was the first investigation of communities and infracommunities of parasites of Hemibrycon surinamensis. All the fish collected in a tributary of the Amazon river were parasitized by one or more parasite species. The Brillouin diversity index (HB) was 0.46 0.28 and the mean species richness was 3.5 1.2 parasites per host. A total of 14,734 parasites were collected, including Ichthyophthirius multifiliis and Piscinoodinium pillulare (Protozoa); Jainus hexops and Tereancistrum sp. (Monogenoidea); Ergasilus turucuyus and Argulus sp. (Crustacea); metacercariae of Derogenidae gen. sp.; metacercariae and adults of Genarchella genarchella (Digenea); and Cucullanus larvae and Contracaecum larvae (Nematoda). The dominant parasite was I. multifiliis, followed by P. pillulare. The parasites showed aggregated dispersion, except for E. turucuyus, which had random dispersion. The condition factor (Kn) indicated that the parasitism levels had not affected host body condition. The high levels of infection observed were due to host behavior, and this was discussed. This was the first report of I. multifiliis, P. pillulare, Argulus sp., E. turucuyus, G. genarchella, J. hexops and Tereancistrum sp. in H. surinamensis, and it expanded the occurrence of E. turucuyus and G. genarchella to the eastern Amazon region. PMID:25271454

Hoshino, Maria Danielle Figueiredo Guimares; Hoshino, Erico Melo; Tavares-Dias, Marcos

2014-01-01

340

Nutrition interacts with parasitism to influence growth and physiology of the insect Manduca sexta L  

Microsoft Academic Search

The influence and interaction of dietary protein:carbohydrate balance and parasitism by Cotesia congregata on nutrient intake and growth were examined over the last two larval stadia of Manduca sexta. Effects of nutritional status on host blood metabolite concentrations were also determined. Six fat-free chemically defined diets were tested, each having the same total level of casein and sucrose, but with

S. N. Thompson; R. A. Redak; L.-W. Wang

2005-01-01

341

Host Cell Phosphatidylcholine Is a Key Mediator of Malaria Parasite Survival during Liver Stage Infection  

PubMed Central

Summary During invasion, Plasmodium, the causative agent of malaria, wraps itself in a parasitophorous vacuole membrane (PVM), which constitutes a critical interface between the parasite and its host cell. Within hepatocytes, each Plasmodium sporozoite generates thousands of new parasites, creating high demand for lipids to support this replication and enlarge thePVM. Here, a global analysis of the total lipid repertoire of Plasmodium-infected hepatocytes reveals an enrichment of neutral lipids and the major membrane phospholipid, phosphatidylcholine (PC). While infection is unaffected in mice deficient in keyenzymes involved in neutral lipid synthesis and lipolysis, ablation of rate-limiting enzymes in hepatic PC biosynthetic pathways significantly decreases parasite numbers. Host PC is taken up by both P.berghei and P.falciparum and is necessary for correct localization of parasite proteins to the PVM, which is essential for parasite survival. Thus, Plasmodium relies on the abundance of these lipids within hepatocytes to support infection. PMID:25498345

Itoe, MauriceA.; Sampaio, JlioL.; Cabal, GhislainG.; Real, Eliana; Zuzarte-Luis, Vanessa; March, Sandra; Bhatia, SangeetaN.; Frischknecht, Friedrich; Thiele, Christoph; Shevchenko, Andrej; Mota, MariaM.

2014-01-01

342

Genome sequencing of chimpanzee malaria parasites reveals possible pathways of adaptation to human hosts  

PubMed Central

Plasmodium falciparum causes most human malaria deaths, having prehistorically evolved from parasites of African Great Apes. Here we explore the genomic basis of P. falciparum adaptation to human hosts by fully sequencing the genome of the closely related chimpanzee parasite species P. reichenowi, and obtaining partial sequence data from a more distantly related chimpanzee parasite (P. gaboni). The close relationship between P. reichenowi and P. falciparum is emphasized by almost complete conservation of genomic synteny, but against this strikingly conserved background we observe major differences at loci involved in erythrocyte invasion. The organization of most virulence-associated multigene families, including the hypervariable var genes, is broadly conserved, but P. falciparum has a smaller subset of rif and stevor genes whose products are expressed on the infected erythrocyte surface. Genome-wide analysis identifies other loci under recent positive selection, but a limited number of changes at the hostparasite interface may have mediated host switching. PMID:25203297

Otto, Thomas D.; Rayner, Julian C.; Bhme, Ulrike; Pain, Arnab; Spottiswoode, Natasha; Sanders, Mandy; Quail, Michael; Ollomo, Benjamin; Renaud, Franois; Thomas, Alan W.; Prugnolle, Franck; Conway, David J.; Newbold, Chris; Berriman, Matthew

2014-01-01

343

Influence of original host on chemotaxic behaviour and parasitism in Telenomus podisi Ashmead (Hymenoptera: Platygastridae).  

PubMed

The egg parasitoid Telenomus podisi is a natural control agent of pentatomids, including Euschistus heros and Tibraca limbativentris, and success of parasitism is dependent upon the parasitoid finding the host. We tested the influence of host egg volatiles and the synthetic sex pheromone (zingiberenol) of T. limbativentris on chemotaxic behaviour of T. podisi, as well as, the impact of the original host on parasitoid selection. We used mated female T. podisi (48h old) that emerged from the eggs of T. limbativentris or E. heros. The bioassays related to chemotaxy were performed in a Y-tube olfactometer and, to parasitism success, in laboratory and semi-field conditions. Telenomus podisi females that emerged from either the stink bug eggs, chose the pheromone more than control, or the pheromone plus eggs of E. heros in the semi-field bioassay, led to greater parasitism. Females that emerged from E. heros eggs chose egg volatiles from their original host rather than those from T. limbativentris, while females emerging from T. limbativentris, chose the egg volatiles of both hosts equally. When T. limbativentris was the original host, T. podisi females parasitized T. limbativentris over E. heros, while those emerging from E. heros exclusively parasitized E. heros eggs. These results demonstrated that T. podisi is more likely to parasitize the host in which it developed and that the original host can exert influence on the choice by those parasitoids. Understanding how the factors that mediate host-parasitoid communication are interrelated can help biological control programmes establish more effective and reliable tools with T. podisi. PMID:25375218

Tognon, R; Sant'Ana, J; Jahnke, S M

2014-12-01

344

Influence of halophytic hosts on their parasites-the case of Plicosepalus acaciae.  

PubMed

Halophytes develop various morphological and physiological traits that enable them to grow successfully on saline substrates. Parasitic plants on halophytic hosts may also encounter salt stress. We investigated the mistletoe Plicosepalus acaciae (syn: Loranthus acacia; Loranthaceae), which occurs on 5 halophytic and at least 10 non-halophytic hosts in the Southern Arava Valley (Israel). Plicosepalus acaciae is a common parasite north of Eilat to the Dead Sea area and in the Jordan Valley. Morphological and physiological responses of P. acaciae to salinity were investigated by comparison of plants on halophytic with those on non-halophytic hosts. Ion patterns of different host-parasite associations were determined as was the development of leaf succulence at different growth stages. The leaf water content of P. acaciae increased and leaves developed succulence when growing on halophytic hosts, especially on Tamarix species, where leaf water content was three times higher than that on non-halophytic hosts and the leaf volume increased four to five times. The reason for increased succulence was a higher ion concentration of, and osmotic adjustment with, Na(+) and Cl(-). Plicosepalus acaciae showed a high morphological and ecophysiological plasticity, enabling it to cope with salt stress, and can be classified as a facultative eu-halophyte, which increases its halo-succulence according to the host. Host-parasite associations are a model system for the investigation of halophytes under different salt stress conditions. PMID:25515726

Veste, Maik; Todt, Henning; Breckle, Siegmar-W

2014-01-01

345

Yersinia pestis Intracellular Parasitism of Macrophages from Hosts Exhibiting High and Low Severity of Plague  

Microsoft Academic Search

BackgroundYersinia pestis causes severe disease in natural rodent hosts, but mild to inapparent disease in certain rodent predators such as dogs. Y. pestis initiates infection in susceptible hosts by parasitizing and multiplying intracellularly in local macrophages prior to systemic dissemination. Thus, we hypothesize that Y. pestis disease severity may depend on the degree to which intracellular Y. pestis overcomes the

Duraisamy Ponnusamy; Kenneth D. Clinkenbeard

2012-01-01

346

Non-random patterns of host use by the different parasite species exploiting a cockle population  

E-print Network

289 Non-random patterns of host use by the different parasite species exploiting a cockle the same definitive host. In the New Zealand cockle, Austrovenus stutchburyi, metacercariae of the digenean is found in different cockle samples, and is independent of cockle shell size, which suggests

Poulin, Robert

347

Biology and host-parasite relations of a species of Meloidoderita (Nematoda : Criconematoidea)  

Microsoft Academic Search

SUMMARY The life history of a population of Meloidoderita Poghossian, 1966, found in Israel, and its host-parasite relations on mint (Mentha longifolia (L) Huds.) were studied. The vermiform second stage female juvenile penetrated Young roots of the host, coming to rest at or near the stele. Sedentary, swollen third and fourth stage juveniles were completely embedded within the root. The

Eli COHN; Mishael MORDECHAI

348

Recognition of social parasites as nest-mates: adoption of colony-specific host cuticular odours by the paper wasp parasite Polistes sulcifer.  

PubMed Central

Colonies of the polistine wasp Polistes dominulus are parasitized by the permanent worker-less social parasite Polistes sulcifer. After usurpation of the host colony, parasite females are characterized by a change in the relative proportions of their cuticular hydrocarbons to match those of the host species. In this paper we present evidence from field data and laboratory experiments that P. sulcifer females adopt a colony-specific host odour that facilitates their acceptance by host females of the usurped colony. Presentation experiments demonstrate that parasite females are recognized as foreign individuals by workers of other parasitized nests. We show that the modification of parasite cuticular compounds is sufficient for this recognition. This provides evidence that, after invasion, P. sulcifer queens do not require appeasement or propaganda substances for their acceptance by host colonies. Furthermore, multivariate discriminant analysis of the cuticular hydrocarbon proportions of the parasites after usurpation assigns the parasites together with P. dominulus females of their own host colony. To the authors' knowledge, this is the first confirmation that social parasites adopt colony-specific host odours. PMID:11674873

Sledge, M. F.; Dani, F. R.; Cervo, R.; Dapporto, L.; Turillazzi, S.

2001-01-01

349

Sex Allocation in Relation to Host Races in the Brood-Parasitic Common Cuckoo (Cuculus canorus)  

PubMed Central

Sex allocation theory and empirical evidence both suggest that natural selection should favour maternal control of offspring sex ratio in relation to their ability to invest in the offspring. Generalist parasites constitute a particularly interesting group to test this theory as different females commonly utilize different host species showing large variation in provisioning ability. The common cuckoo (Cuculus canorus) is a generalist brood parasite that lays its eggs in the nest of many different passerine birds, but each female tends to specialize on one particular host species giving rise to highly specialized host races. The different host species show large variation in their ability to invest in the parasitic offspring, presenting an opportunity for female cuckoos to bias offspring sex ratio in relation to host species quality. Here, we investigate host-race specific sex allocation controlling for maternal identity in the common cuckoo. We found no evidence of any significant relationship between host race and sex ratio in one sympatric population harbouring three different host races, or in a total of five geographically separated populations. There was also no significant association between host quality, as determined by species-specific female host body mass, and cuckoo sex ratio. Finally, we found no significant relationship between individual cuckoo maternal quality, as determined by her egg volume, and sex ratio within each host race. We conclude that the generalist brood-parasitic common cuckoo show no significant sex-ratio bias in relation to host race and discuss this finding in light of gene flow and host adaptations. PMID:22615833

Fossy, Frode; Moksnes, Arne; Rskaft, Eivin; Antonov, Anton; Dyrcz, Andrzej; Moskat, Csaba; Ranke, Peter S.; Rutila, Jarkko; Vikan, Johan R.; Stokke, Brd G.

2012-01-01

350

Parasitism by Cuscuta pentagona attenuates host plant defenses against insect herbivores.  

PubMed

Considerable research has examined plant responses to concurrent attack by herbivores and pathogens, but the effects of attack by parasitic plants, another important class of plant-feeding organisms, on plant defenses against other enemies has not been explored. We investigated how attack by the parasitic plant Cuscuta pentagona impacted tomato (Solanum lycopersicum) defenses against the chewing insect beet armyworm (Spodoptera exigua; BAW). In response to insect feeding, C. pentagona-infested (parasitized) tomato plants produced only one-third of the antiherbivore phytohormone jasmonic acid (JA) produced by unparasitized plants. Similarly, parasitized tomato, in contrast to unparasitized plants, failed to emit herbivore-induced volatiles after 3 d of BAW feeding. Although parasitism impaired antiherbivore defenses, BAW growth was slower on parasitized tomato leaves. Vines of C. pentagona did not translocate JA from BAW-infested plants: amounts of JA in parasite vines grown on caterpillar-fed and control plants were similar. Parasitized plants generally contained more salicylic acid (SA), which can inhibit JA in some systems. Parasitized mutant (NahG) tomato plants deficient in SA produced more JA in response to insect feeding than parasitized wild-type plants, further suggesting cross talk between the SA and JA defense signaling pathways. However, JA induction by BAW was still reduced in parasitized compared to unparasitized NahG, implying that other factors must be involved. We found that parasitized plants were capable of producing induced volatiles when experimentally treated with JA, indicating that resource depletion by the parasite does not fully explain the observed attenuation of volatile response to herbivore feeding. Collectively, these findings show that parasitic plants can have important consequences for host plant defense against herbivores. PMID:18165323

Runyon, Justin B; Mescher, Mark C; De Moraes, Consuelo M

2008-03-01

351

Parasitism by Cuscuta pentagona Attenuates Host Plant Defenses against Insect Herbivores1  

PubMed Central

Considerable research has examined plant responses to concurrent attack by herbivores and pathogens, but the effects of attack by parasitic plants, another important class of plant-feeding organisms, on plant defenses against other enemies has not been explored. We investigated how attack by the parasitic plant Cuscuta pentagona impacted tomato (Solanum lycopersicum) defenses against the chewing insect beet armyworm (Spodoptera exigua; BAW). In response to insect feeding, C. pentagona-infested (parasitized) tomato plants produced only one-third of the antiherbivore phytohormone jasmonic acid (JA) produced by unparasitized plants. Similarly, parasitized tomato, in contrast to unparasitized plants, failed to emit herbivore-induced volatiles after 3 d of BAW feeding. Although parasitism impaired antiherbivore defenses, BAW growth was slower on parasitized tomato leaves. Vines of C. pentagona did not translocate JA from BAW-infested plants: amounts of JA in parasite vines grown on caterpillar-fed and control plants were similar. Parasitized plants generally contained more salicylic acid (SA), which can inhibit JA in some systems. Parasitized mutant (NahG) tomato plants deficient in SA produced more JA in response to insect feeding than parasitized wild-type plants, further suggesting cross talk between the SA and JA defense signaling pathways. However, JA induction by BAW was still reduced in parasitized compared to unparasitized NahG, implying that other factors must be involved. We found that parasitized plants were capable of producing induced volatiles when experimentally treated with JA, indicating that resource depletion by the parasite does not fully explain the observed attenuation of volatile response to herbivore feeding. Collectively, these findings show that parasitic plants can have important consequences for host plant defense against herbivores. PMID:18165323

Runyon, Justin B.; Mescher, Mark C.; De Moraes, Consuelo M.

2008-01-01

352

Table 1: Examples of direct and indirect effects of parasites in biological invasions. Host(s)Parasite(s) system Direct effect of parasite on  

E-print Network

trematode exposure Poulin et al. 2011 H: Invasive Mediterranean marine mussel Mytilus galloprovincialis; Borer et al. 2007 #12;4 H: Invasive weed, Chromolaena odorata and native plants P: Fungal pathogen1 Table 1: Examples of direct and indirect effects of parasites in biological invasions. Host

Holt, Robert D.

353

Brood parasitism increases provisioning rate, and reduces offspring recruitment and adult return rates, in a cowbird host  

Microsoft Academic Search

Interspecific brood parasitism in birds presents a special problem for the host because the parasitic offspring exploit their foster parents, causing them to invest more energy in their current reproductive effort. Nestling brown-headed cowbirds (Molothrus ater) are a burden to relatively small hosts and may reduce fledgling quality and adult survival. We documented food-provisioning rates of one small host, the

Jeffrey P. Hoover; Matthew J. Reetz

2006-01-01

354

Who benefits from reduced reproduction in parasitized hosts? An experimental test using the Pasteuria ramosa-Daphnia magna system.  

PubMed

We investigated whether parasites or hosts benefit from reduced reproduction in infected hosts. When parasites castrate their hosts, the regain of host reproduction is necessary for castration to be a host adaptation. When infecting Daphnia magna with Pasteuria ramosa, in a lake water based medium, 49 2% of the castrated females regained reproduction. We investigated the relationship between castration level, and parasite and host fitness proxies to determine the adaptive value of host castration. Hosts which regained reproduction contained less spores and had a higher lifetime reproduction than permanently castrated hosts. We also found a negative correlation between parasite and host lifetime reproduction. For hosts which regained reproduction we found no optimal level of castration associated with lifetime reproduction. These results support the view that host castration only is adaptive to the parasite in this system. In addition, we suggest that permanent castration might not be the norm under natural conditions in this system. Finally, we argue that a reduction in host reproduction is more likely to evolve as a property favouring parasites rather than hosts. To our knowledge this is the only experimental study to investigate the adaptive value of reduced host reproduction when castrated hosts can regain reproduction. PMID:21854675

Mageroy, Jon H; Grepperud, Eldfrid J; Jensen, Knut Helge

2011-12-01

355

Epimerite-Host Epithelium Relationships among Eugregarines Parasitizing the Damselflies Enallagma civile and Ischnura verticalis  

Microsoft Academic Search

The host-parasite interface between two species of damselflies and four species of eugregarines was examined at the ultrastructural level. Nubenocephalus nebraskensis organisms attached to the host midgut epithelium by means of a sucker-like protomerite; the space between the epicytic folds and host epithelium was filled with electron-dense material interpreted to be adhesive in nature. Actinocephalus carrilynnae organisms attached by means

Tamara J. Percival Cook; Janovy John J. Jr; Richard E. Clopton

2001-01-01

356

Factors influencing host nest use by the brood parasitic Asian Koel ( Eudynamys scolopacea )  

Microsoft Academic Search

Host nest use by the brood parasitic Asian Koel (Eudynamys scolopacea) has not previously been studied in detail. Here, we investigated factors that may explain patterns of nest use among three\\u000a commonly used host species of the Asian Koel in Bangladesh; Long-tailed Shrikes (Lanius schach), House Crows (Corvus splendens) and Common Mynas (Acridotheres tristis). In all three host species, the

Sajeda Begum; Arne Moksnes; Eivin Rskaft; Brd G. Stokke

2011-01-01

357

Relative importance of host environment, transmission potential and host phylogeny to the structure of parasite metacommunities  

E-print Network

to the structure of parasite metacommunities Tad Dallas and Steven J. Presley T. Dallas (tdallas@uga.edu), Odum, Storrs, CT 06269­4210, USA. Identification of mechanisms that shape parasite community and metacommunity of community assembly in general. Using a long-term dataset on parasites from desert rodents, we examined

Willig, Michael

358

Evidence for gene flow in parasitic nematodes between two host species of shrews.  

PubMed

We describe the genetic structure of populations of the intestinal nematode Longistriata caudabullata (Trichostrongyloidea: Heligmosomidae), a common parasite of short-tailed shrews (genus Blarina, Insectivora: Soricidae). Parasites and hosts were collected from a transect across a contact zone between two species of hosts, Blarina brevicauda and B. hylophaga, in central North America. An 800-base pairs (bp) fragment of the ND4 mitochondrial DNA (mtDNA) gene was sequenced for 28 worms and a 783-bp fragment of the mtDNA control region was analysed for 16 shrews. Phylogenetic analyses of mtDNA sequences revealed reciprocal monophyly for the shrew species, concordant with morphological diagnosis, and supported the idea that the transect cuts through a secondary contact zone between well-differentiated B. brevicauda and B. hylophaga. In contrast to this pattern, the parasitic nematode mtDNA phylogeny was not subdivided according to host affiliation. Genealogical discordance between parasite and host phylogenies suggests extensive gene flow among parasites across the host species boundary. PMID:12969487

Brant, Sara V; Ort, Guillermo

2003-10-01

359

Hijacking of host cellular functions by an intracellular parasite, the microsporidian Anncaliia algerae.  

PubMed

Intracellular pathogens including bacteria, viruses and protozoa hijack host cell functions to access nutrients and to bypass cellular defenses and immune responses. These strategies have been acquired through selective pressure and allowed pathogens to reach an appropriate cellular niche for their survival and growth. To get new insights on how parasites hijack host cellular functions, we developed a SILAC (Stable Isotope Labeling by Amino Acids in Cell culture) quantitative proteomics workflow. Our study focused on deciphering the cross-talk in a host-parasite association, involving human foreskin fibroblasts (HFF) and the microsporidia Anncaliia algerae, a fungus related parasite with an obligate intracellular lifestyle and a strong host dependency. The host-parasite cross-talk was analyzed at five post-infection times 1, 6, 12 and 24 hours post-infection (hpi) and 8 days post-infection (dpi). A significant up-regulation of four interferon-induced proteins with tetratricopeptide repeats IFIT1, IFIT2, IFIT3 and MX1 was observed at 8 dpi suggesting a type 1 interferon (IFN) host response. Quantitative alteration of host proteins involved in biological functions such as signaling (STAT1, Ras) and reduction of the translation activity (EIF3) confirmed a host type 1 IFN response. Interestingly, the SILAC approach also allowed the detection of 148 A. algerae proteins during the kinetics of infection. Among these proteins many are involved in parasite proliferation, and an over-representation of putative secreted effectors proteins was observed. Finally our survey also suggests that A. algerae could use a transposable element as a lure strategy to escape the host innate immune system. PMID:24967735

Panek, Johan; El Alaoui, Hicham; Mone, Anne; Urbach, Serge; Demettre, Edith; Texier, Catherine; Brun, Christine; Zanzoni, Andreas; Peyretaillade, Eric; Parisot, Nicolas; Lerat, Emmanuelle; Peyret, Pierre; Delbac, Frederic; Biron, David G

2014-01-01

360

A slowly evolving host moves first in symbiotic interactions  

NASA Astrophysics Data System (ADS)

Symbiotic relationships, both parasitic and mutualistic, are ubiquitous in nature. Understanding how these symbioses evolve, from bacteria and their phages to humans and our gut microflora, is crucial in understanding how life operates. Often, symbioses consist of a slowly evolving host species with each host only interacting with its own sub-population of symbionts. The Red Queen hypothesis describes coevolutionary relationships as constant arms races with each species rushing to evolve an advantage over the other, suggesting that faster evolution is favored. Here, we use a simple game theoretic model of host- symbiont coevolution that includes population structure to show that if the symbionts evolve much faster than the host, the equilibrium distribution is the same as it would be if it were a sequential game where the host moves first against its symbionts. For the slowly evolving host, this will prove to be advantageous in mutualisms and a handicap in antagonisms. The model allows for symbiont adaptation to its host, a result that is robust to changes in the parameters and generalizes to continuous and multiplayer games. Our findings provide insight into a wide range of symbiotic phenomena and help to unify the field of coevolutionary theory.

Damore, James; Gore, Jeff

2011-03-01

361

In Planta Processing and Glycosylation of a Nematode CLAVATA3/ENDOSPERM SURROUNDING REGION-Like Effector and Its Interaction with a Host CLAVATA2-Like Receptor to Promote Parasitism.  

PubMed

Like other biotrophic plant pathogens, plant-parasitic nematodes secrete effector proteins into host cells to facilitate infection. Effector proteins that mimic plant CLAVATA3/ENDOSPERM SURROUNDING REGION-related (CLE) proteins have been identified in several cyst nematodes, including the potato cyst nematode (PCN); however, the mechanistic details of this cross-kingdom mimicry are poorly understood. Plant CLEs are posttranslationally modified and proteolytically processed to function as bioactive ligands critical to various aspects of plant development. Using ectopic expression coupled with nanoliquid chromatography-tandem mass spectrometry analysis, we show that the in planta mature form of proGrCLE1, a multidomain CLE effector secreted by PCN during infection, is a 12-amino acid arabinosylated glycopeptide (named GrCLE1-1Hyp4,7g) with striking structural similarity to mature plant CLE peptides. This glycopeptide is more resistant to hydrolytic degradation and binds with higher affinity to a CLAVATA2-like receptor (StCLV2) from potato (Solanum tuberosum) than its nonglycosylated forms. We further show that StCLV2 is highly up-regulated at nematode infection sites and that transgenic potatoes with reduced StCLV2 expression are less susceptible to PCN infection, indicating that interference of the CLV2-mediated signaling pathway confers nematode resistance in crop plants. These results strongly suggest that phytonematodes have evolved to utilize host cellular posttranslational modification and processing machinery for the activation of CLE effectors following secretion into plant cells and highlight the significance of arabinosylation in regulating nematode CLE effector activity. Our finding also provides evidence that multidomain CLEs are modified and processed similarly to single-domain CLEs, adding new insight into CLE maturation in plants. PMID:25416475

Chen, Shiyan; Lang, Ping; Chronis, Demosthenis; Zhang, Sheng; De Jong, Walter S; Mitchum, Melissa G; Wang, Xiaohong

2015-01-01

362

In Planta Processing and Glycosylation of a Nematode CLAVATA3/ENDOSPERM SURROUNDING REGION-Like Effector and Its Interaction with a Host CLAVATA2-Like Receptor to Promote Parasitism1[OPEN  

PubMed Central

Like other biotrophic plant pathogens, plant-parasitic nematodes secrete effector proteins into host cells to facilitate infection. Effector proteins that mimic plant CLAVATA3/ENDOSPERM SURROUNDING REGION-related (CLE) proteins have been identified in several cyst nematodes, including the potato cyst nematode (PCN); however, the mechanistic details of this cross-kingdom mimicry are poorly understood. Plant CLEs are posttranslationally modified and proteolytically processed to function as bioactive ligands critical to various aspects of plant development. Using ectopic expression coupled with nanoliquid chromatography-tandem mass spectrometry analysis, we show that the in planta mature form of proGrCLE1, a multidomain CLE effector secreted by PCN during infection, is a 12-amino acid arabinosylated glycopeptide (named GrCLE1-1Hyp4,7g) with striking structural similarity to mature plant CLE peptides. This glycopeptide is more resistant to hydrolytic degradation and binds with higher affinity to a CLAVATA2-like receptor (StCLV2) from potato (Solanum tuberosum) than its nonglycosylated forms. We further show that StCLV2 is highly up-regulated at nematode infection sites and that transgenic potatoes with reduced StCLV2 expression are less susceptible to PCN infection, indicating that interference of the CLV2-mediated signaling pathway confers nematode resistance in crop plants. These results strongly suggest that phytonematodes have evolved to utilize host cellular posttranslational modification and processing machinery for the activation of CLE effectors following secretion into plant cells and highlight the significance of arabinosylation in regulating nematode CLE effector activity. Our finding also provides evidence that multidomain CLEs are modified and processed similarly to single-domain CLEs, adding new insight into CLE maturation in plants. PMID:25416475

Chen, Shiyan; Lang, Ping; Chronis, Demosthenis; Zhang, Sheng; De Jong, Walter S.; Mitchum, Melissa G.

2015-01-01

363

Lessons from parasitic flatworms about evolution and historical biogeography of their vertebrate hosts.  

PubMed

Cophylogenetic studies investigate the evolutionary trends within host-parasite associations. Examination of the different levels of fidelity between host and parasite phylogenies provides a powerful tool to inspect patterns and processes of parasite diversification over host evolution and geological times. Within the phylum Platyhelminthes, the monogeneans are mainly fish parasites. The Polystomatidae, however, are known from the sarcopterygian Australian lungfish and tetrapods such as amphibians, freshwater turtles, and the African hippopotamus. Cophylogenetic and biogeographic vicariance analyses, supplemented by molecular calibrations, showed that the Polystomatidae may track the evolutionary history of the first aquatic tetrapods in the Palaeozoic age. Evolutionary lines of the major polystome lineages would also be intimately related to the evolution of their hosts over hundreds of millions years. Since the Mesozoic, evolution of polystomes would have been shaped mainly by plate tectonics during the break-up of Gondwanaland and subsequent dispersal of ancestral neobatrachian host lineages. Therefore the Polystomatidae could serve as a novel model to improve cophylogenetic tools and to inspect a suite of questions about the evolution of vertebrate hosts. PMID:19281948

Verneau, Olivier; Du Preez, Louis; Badets, Mathieu

2009-01-01

364

Malaria infected erythrocyte-derived microvesicles mediate cellular communication within the parasite population and with the host immune system  

PubMed Central

Summary Humans and mice infected with different Plasmodium strains are known to produce microvesicles derived from the infected red blood cells (RBC), denoted RMVs. Studies in mice have shown that RMVs are elevated during infection and have pro-inflammatory activity. Here we present a detailed characterization of RMV composition and function in the human malaria parasite Plasmodium falciparum. Proteomics profiling revealed the enrichment of multiple host and parasite proteins, in particular of parasite antigens associated with host cell membranes and proteins involved in parasite invasion into RBCs. RMVs are quantitatively released during the asexual parasite cycle prior to parasite egress. RMVs demonstrate potent immunomodulatory properties on human primary macrophages and neutrophils. Additionally, RMVs are internalized by infected red blood cells and stimulate production of transmission stage parasites in a dose-dependent manner. Thus, RMVs mediate cellular communication within the parasite population and with the host innate immune system. PMID:23684304

Mantel, Pierre-Yves; Hoang, Anh N.; Goldowitz, Ilana; Potashnikova, Daria; Hamza, Bashar; Vorobjev, Ivan; Ghiran, Ionita; Toner, Mehmet; Irimia, Daniel; Ivanov, Alexander R.; Barteneva, Natasha; Marti, Matthias

2013-01-01

365

Parasitic manipulation of hosts' phenotype, or how to make a zombie--an introduction to the symposium.  

PubMed

Nearly all animals in nature are infected by at least one parasite, and many of those parasites can significantly change the phenotype of their hosts, often in ways that increase the parasite's likelihood of transmission. Hosts' phenotypic changes are multidimensional, and manipulated traits include behavior, neurotransmission, coloration, morphology, and hormone levels. The field of parasitic manipulation of hosts' phenotype has now accrued many examples of systems where parasites manipulate the phenotypes of their hosts and focus has shifted to answering three main questions. First, through what mechanisms do parasites manipulate the hosts' phenotype? Parasites often induce changes in the hosts' phenotypes that neuroscientists are unable to recreate under laboratory conditions, suggesting that parasites may have much to teach us about links between the brain, immune system, and the expression of phenotype. Second, what are the ecological implications of phenotypic manipulation? Manipulated hosts are often abundant, and changes in their phenotype may have important population, community, and ecosystem-level implications. Finally, how did parasitic manipulation of hosts' phenotype evolve? The selective pressures faced by parasites are extremely complex, often with multiple hosts that are actively resisting infection, both in physiological and evolutionary time-scales. Here, we provide an overview of how the work presented in this special issue contributes to tackling these three main questions. Studies on parasites' manipulation of their hosts' phenotype are undertaken largely by parasitologists, and a major goal of this symposium is to recruit researchers from other fields to the study of these phenomena. Our ability to answer the three questions outlined above would be greatly enhanced by participation from individuals trained in the fields of, for example, neurobiology, physiology, immunology, ecology, evolutionary biology, and invertebrate biology. Conversely, because parasites that alter their hosts' phenotype are widespread, these fields will benefit from such study. PMID:24771088

Weinersmith, Kelly; Faulkes, Zen

2014-07-01

366

Lower Begging Responsiveness of Host Versus Parasitic Brown-Headed Cowbird (Molothrus ater) Nestlings Is Related to Species Identity but Not to Early Social Experience  

Microsoft Academic Search

The survival of young brood parasites depends critically on their many adaptations to exploit hosts. Parasitic survival is particularly related to competitive superiority for foster parental care whenever host young are not destroyed in parasitized nests. Brown-headed cowbirds (Molothrus ater) are generalist obligate parasites whose early social environments are unpredictable regarding host species and numbers of estmates. Young avian brood

Mark E. Hauber

2003-01-01

367

Parasites as biological tags to assess host population structure: Guidelines, recent genetic advances and comments on a holistic approach?  

PubMed Central

We review the use of parasites as biological tags of marine fishes and cephalopods in host population structure studies. The majority of the work published has focused on marine fish and either single parasite species or more recently, whole parasite assemblages, as biological tags. There is representation of host organisms and parasites from a diverse range of taxonomic groups, although focus has primarily been on host species of commercial importance. In contrast, few studies have used parasites as tags to assess cephalopod population structure, even though records of parasites infecting cephalopods are well-documented. Squid species are the only cephalopod hosts for which parasites as biological tags have been applied, with anisakid nematode larvae and metacestodes being the parasite taxa most frequently used. Following a brief insight into the importance of accurate parasite identification, the population studies that have used parasites as biological tags for marine fishes and cephalopods are reviewed, including comments on the dicyemid mesozoans. The advancement of molecular genetic techniques is discussed in regards to the new ways parasite genetic data can be incorporated into population structure studies, alongside host population genetic analyses, followed by an update on the guidelines for selecting a parasite species as a reliable tag candidate. As multiple techniques and methods can be used to assess the population structure of marine organisms (e.g. artificial tags, phenotypic characters, biometrics, life history, genetics, otolith microchemistry and parasitological data), we conclude by commenting on a holistic approach to allow for a deeper insight into population structuring. PMID:25197624

Catalano, Sarah R.; Whittington, Ian D.; Donnellan, Stephen C.; Gillanders, Bronwyn M.

2013-01-01

368

Parasite diversity/host age and size relationship in three coral-reef fishes from French Polynesia.  

PubMed

The parasite communities of three coral-reef fish species (Stegastes nigricans, Dascyllus aruanus and Cephalopholis argus) were on Tiahura reef, French Polynesia. The age and growth of each fish was analysed by otolith increment counts and a significant correlation between these variables was found. Stegastes nigricans was parasitised by six adult parasite species, D. aruanus by two adult parasite species and C. argus by five adult parasite species. The most common parasite species were found in all fish size classes. Ectoparasites showed a positive relationship between their abundance and host body length for all three reef fish species. A positive relationship was found only between host size and parasite abundance for common endoparasite species. Parasite species richness, Brillouin's diversity index, and host size and age were positively related. Finally, we discuss the influence of different biological (host diet, host immune response, parasite life-cycle) and ecological factors on parasite community structure in these three reef fishes. Host diet quality seems to be one of the major factors affecting the endoparasite community structure in these reef fishes. Ectoparasite communities seem to be influenced more by biological factors such as, for example, host immunity for the caligid larvae or parasite life-cycle for the gnathiid praniza larvae. In addition, the effect of ecological factors such as cleaning symbiosis on these ectoparasites cannot be dismissed. PMID:9846606

Lo, C M; Morand, S; Galzin, R

1998-11-01

369

Host microbe interactions: a licence to interfere?  

PubMed

Through many millennia of continuous evolution hosts and microorganisms have developed sophisticated and sometimes extremely complex mechanisms of coexisting through symbiosis and mutualism. It is now known that in humans, the population of commensal bacteria on or inside the body significantly outnumbers the host cells. Despite their numerical superiority, microorganisms have adjusted their physiological clocks to benefit themselves and at the same time their host through the maintenance of a healthy state. This very fine and multifaceted balance can be disrupted occasionally through the introduction of pathogens in the commensal bacterial population. The equilibrium is then perturbed to promote dysbiosis and the onset of disease. Through myriads of interactions within their host milieu, bacterial pathogens have developed mechanisms to sense bacterial or host-derived signalling molecules and adjust their physiology accordingly to favour their survival and propagation within their host. At the same time, the host has evolved systems to interfere with bacterial signalling in such a way as to support pathogen clearing and re-establishment of the balance. An example of a captivating interaction is the one involving the catecholamine hormones adrenaline and noradrenaline. This article will summarise the major findings involving host pathogen communication through bacterial or host-derived molecules and discuss ways to take advantage of our potential to interfere with this intricate signalling to profit the host and prolong a healthy life. PMID:25420724

Karavolos, Michail H

2015-01-01

370

Parasite pathogenicity and the depression of host population equilibria  

Microsoft Academic Search

THE use of pathogens as agents for the biological control of pest species has increased rapidly in recent years with the realisation that chemical pesticides are not the panacea they were once thought to be1-6. The selection of a suitable parasite is often based on the assumption that highly pathogenic organisms will be most effective in minimising pest population growth6-8.

Roy M. Anderson

1979-01-01

371

The ecology of fish parasites with particular reference to helminth parasites and their salmonid fish hosts in Welsh rivers: a review of some of the central questions.  

PubMed

Ecological studies carried out in Welsh rivers on the feeding behaviour of salmonid fish, their helminth parasites and intermediate hosts in the early 1950s and in 1998 have been used as a basis to review the literature dealing with the following questions. First, how are the helminth populations dispersed in space-time? Second, to what extent are the distributional patterns and the life history strategies of the parasites influenced by physicochemical factors? Third, to what extent are populations of helmith parasites in salmonid fish influenced by host characteristics including the genome, sex, age, size, social position and Feeding behaviour? Fourth, are the populations of parasites regulated in a density-dependent manner? Fifth, do the parasites influence the survival and wellbeing of their salmonid hosts and the evolution of sex? Sixth, to what extent is the parasite community influenced by environmental changes including those of an anthropogenic nature and can the parasites be used as bioindicators of pollution? As with most parasites the helminth species found were highly overdispersed thus making it necessary to undertake a log10 (1 + x) conversion for statistical analyses. Statistical analyses confirm that the genome, age and sex of salmonid fish hosts, the station and seasonal change in radiation levels were significant factors in predicting the number of parasites. The evidence given supports the hypothesis that the feeding behaviour and habitat selection by the host fish, their position in the social hierarchy and the overdispersed nature of the transmission sites are the key factors in causing differences in the parasitic fauna related to host species, age, size and sex. Differences in the helminth parasite community related to station can be explained on the basis of differences in water types, sediments and chemistry. Although the evidence presented is in accord with the consensus view that temperature is correlated with seasonal changes in the abundance of many species of helminth parasites, it is argued that it may not be the direct causative mechanism. It is postulated that the life history strategy that results in a decline in abundance of the more vulnerable adult parasites in the gut of the salmonid hosts during the summer has arisen as a result of evolutionary pressures. At this time, the gut environment is particularly inhospitable because of the temperature-related enhancement of the host's immune mechanism and the increased gut turnover rate. In contrast, the larval stages in the immunologically and metabolically more benign intermediate host would be under less intensive selective pressures. It is postulated therefore that evolutionary pressures have caused the parasites to leave the definitive host and concentrate their reproductive efforts in the intermediate hosts during the warmer months. Evidence is given in support of the hypothesis that the parasite populations are regulated in a density-dependent manner and that the regulatory mechanisms may involve the host's immune mechanisms and intraspecies competition and interspecies competition of an exploitative or interference nature. Quantitative studies using 'K' factor analysis and biochemical research to elucidate the nature of the interference mechanisms are required to test this hypothesis. The absence of age-related resistance indicates an old and stable relationship in which the immunosuppressive and immunoavoidance mechanisms of the parasites and hosts, respectively, are in balance. This indicates that the introduction of novel parasites or new genetic strains of host fish could result in harmful epidemics. Despite causing tissue damage, there was no evidence of parasite-induced mortality among the salmonids in the Teifi. This finding is in accord with the generally accepted view that most freshwaters are not troubled by parasite problems. although parasites are present in abundance. In fact, parasite abundance in the salmonid fish in the Teifi was positively correlated with the condition factor and the adipose index. Two testable hypo

Thomas, J D

2002-01-01

372

Effects of Juvenile Host Density and Food Availability on Adult Immune Response, Parasite Resistance and Virulence in a Daphnia-Parasite System  

PubMed Central

Host density can increase infection rates and reduce host fitness as increasing population density enhances the risk of becoming infected either through increased encounter rate or because host condition may decline. Conceivably, potential hosts could take high host density as a cue to up-regulate their defence systems. However, as host density usually covaries with food availability, it is difficult to examine the importance of host density in isolation. Thus, we performed two full-factorial experiments that varied juvenile densities of Daphnia magna (a freshwater crustacean) and food availability independently. We also included a simulated high-density treatment, where juvenile experimental animals were kept in filtered media that previously maintained Daphnia at high-density. Upon reaching adulthood, we exposed the Daphnia to their sterilizing bacterial parasite, Pasteuria ramosa, and examined how the juvenile treatments influenced the likelihood and severity of infection (Experiment I) and host immune investment (Experiment II). Neither juvenile density nor food treatments affected the likelihood of infection; however, well-fed hosts that were well-fed as juveniles produced more offspring prior to sterilization than their less well-fed counterparts. By contrast, parasite growth was independent of host juvenile resources or host density. Parasite-exposed hosts had a greater number of circulating haemocytes than controls (i.e., there was a cellular immune response), but the magnitude of immune response was not mediated by food availability or host density. These results suggest that density dependent effects on disease arise primarily through correlated changes in food availability: low food could limit parasitism and potentially curtail epidemics by reducing both the hosts and parasites reproduction as both depend on the same food. PMID:24736707

Schoebel, Corine N.; Auld, Stuart K. J. R.; Spaak, Piet; Little, Tom J.

2014-01-01

373

Treponema denticola interactions with host proteins  

PubMed Central

Oral Treponema species, most notably T. denticola, are implicated in the destructive effects of human periodontal disease. Progress in the molecular analysis of interactions between T. denticola and host proteins is reviewed here, with particular emphasis on the characterization of surface-expressed and secreted proteins of T. denticola involved in interactions with host cells, extracellular matrix components, and components of the innate immune system. PMID:22368767

Fenno, J. Christopher

2012-01-01

374

Virulence of lizard malaria: the evolutionary ecology of an ancient parasite-host association.  

PubMed

The negative consequences of parasitic infection (virulence) were examined for two lizard malaria parasite-host associations: Plasmodium agamae and P. giganteum, parasites of the rainbow lizard, Agama agama, in Sierra Leone, West Africa; and P. mexicanum in the western fence lizard, Sceloporus occidentalis, in northern California. These malaria species vary greatly in their reproductive characteristics: P. agamae produces only 8 merozoites per schizont, P. giganteum yields over 100, and P. mexicanum an intermediate number. All three parasites appear to have had an ancient association with their host. In fence lizards, infection with malaria is associated with increased numbers of immature erythrocytes, decreased haemoglobin levels, decreased maximal oxygen consumption, and decreased running stamina. Not affected were numbers of erythrocytes, resting metabolic rate, and sprint running speed which is supported by anaerobic means in lizards. Infected male fence lizards had smaller testes, stored less fat in preparation for winter dormancy, were more often socially submissive and, unexpectedly, were more extravagantly coloured on the ventral surface (a sexually dimorphic trait) than non-infected males. Females also stored less fat and produced smaller clutches of eggs, a directly observed reduction in fitness. Infected fence lizards do not develop behavioural fevers. P. mexicanum appears to have broad thermal buffering abilities and thermal tolerance; the parasite's population growth was unaffected by experimental alterations in the lizard's body temperature. The data are less complete for A. agama, but infected lizards suffered similar haematological and physiological effects. Infected animals may be socially submissive because they appear to gather less insect prey, possibly a result of being forced into inferior territories. Infection does not reduce clutch size in rainbow lizards, but may lengthen the time between clutches. These results are compared with predictions emerging from several models of the evolution of parasite virulence. The lack of behavioural fevers in fence lizards may represent a physiological constraint by the lizards in evolving a thermal tolerance large enough to allow elimination of the parasite via fever. Such constraints may be important in determining the outcome of parasite-host coevolution. Some theory predicts low virulence in old parasite-host systems and higher virulence in parasites with greater reproductive output. However, in conflict with this argument, all three malarial species exhibited similar high costs to their hosts. PMID:2235062

Schall, J J

1990-01-01

375

Molecular parasitism in the Escherichia coli-Bdellovibrio bacteriovorus system: translocation of the matrix protein from the host to the parasite outer membrane.  

PubMed Central

During the intracellular maturation in Escherichia coli of the parasite Bdellovibrio bacteriovorus the outer membrane, major protein I of E. coli (i.e., the matrix protein) becomes associated with the outer membrane of the emerging parasite cells. The binding properties of this protein with the outer membrane of the host and of the parasite are identical. An analogous phenomenon also occurs during Bdellovibrio parasitism on Klebsiella pneumoniae and on Salmonella typhimurium. Possible roles for this scavenging action of Bdellovibrio, and similar phenomena in other parasitic systems, are discussed. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:6765198

Guerrini, F; Romano, V; Valenzi, M; Di Giulio, M; Mupo, M R; Sacco, M

1982-01-01

376

The expression of virulence during double infections by different parasites with conflicting host exploitation and transmission strategies.  

PubMed

In many natural populations, hosts are found to be infected by more than one parasite species. When these parasites have different host exploitation strategies and transmission modes, a conflict among them may arise. Such a conflict may reduce the success of both parasites, but could work to the benefit of the host. For example, the less-virulent parasite may protect the host against the more-virulent competitor. We examine this conflict using the waterflea Daphnia magna and two of its sympatric parasites: the blood-infecting bacterium Pasteuria ramosa that transmits horizontally and the intracellular microsporidium Octosporea bayeri that can concurrently transmit horizontally and vertically after infecting ovaries and fat tissues of the host. We quantified host and parasite fitness after exposing Daphnia to one or both parasites, both simultaneously and sequentially. Under conditions of strict horizontal transmission, Pasteuria competitively excluded Octosporea in both simultaneous and sequential double infections, regardless of the order of exposure. Host lifespan, host reproduction and parasite spore production in double infections resembled those of single infection by Pasteuria. When hosts became first vertically (transovarilly) infected with O.bayeri, Octosporea was able to withstand competition with P.ramosa to some degree, but both parasites produced less transmission stages than they did in single infections. At the same time, the host suffered from reduced fecundity and longevity. Our study demonstrates that even when competing parasite species utilize different host tissues to proliferate, double infections lead to the expression of higher virulence and ultimately may select for higher virulence. Furthermore, we found no evidence that the less-virulent and vertically transmitting O.bayeri protects its host against the highly virulent P.ramosa. PMID:21481055

Ben-Ami, F; Rigaud, T; Ebert, D

2011-06-01

377

Parasite strain coexistence in a heterogeneous host population Darren M. Green, Istvan Z. Kiss and Rowland R. Kao  

E-print Network

Parasite strain coexistence in a heterogeneous host population Darren M. Green, Istvan Z. Kiss and Rowland R. Kao Green, D. M., Kiss, I. Z. and Kao, R. R. 2006. Parasite strain coexistence to parasite attack allows a lower transmission rate to sustain an epidemic than is required in homogeneous

Kiss, Istvan Zoltan

378

Effects of Intra- and Interpatch Host Density on Egg Parasitism by Three Species of Trichogramma  

PubMed Central

Host-foraging responses to different intra- and interpatch densities were used to assess three Trichogramma spp. (Hymenoptera: Trichogrammatidae) Trichogramma deion Pinto and Oatman, T. ostriniae Pang and Chen, and T. pretiosum Riley as potential biological control agents for the Indian meal moth, Plodia interpunctella Hbner (Lepidoptera: Pyralidae). Single nave females were allowed 6 h to forage in Plexiglas arenas with four different spatial arrangements of host eggs, nine single-egg patches), nine four-egg patches, 36 single-egg patches, and 36 four-egg patches. No significant differences were found among species in the number of patches parasitized. As expected, all three species parasitized the most eggs in the 36 four-egg patch treatment and the least in the nine single-egg patch treatment. T. deion parasitized significantly more eggs than T. pretiosum on the nine four-egg patches. T. ostriniae parasitized significantly more patches when intrapatch density was greater, regardless of interpatch density. In contrast, T. deion only parasitized more patches at the greater intrapatch density when the interpatch density was low. Patch density had no effect on T. pretiosum. The spatial pattern of parasitism was more aggregated for T. deion and T. ostriniae in the 36 four-egg patches treatment compared to the 36 single-egg patches treatment. Therefore, intrapatch density was more important than interpatch density for T. ostriniae, and potentially for T. deion, but not for T. pretiosum. T. deion may be the best candidate for augmentative biological control because it parasitized either slightly or significantly more eggs than the other two species in all four treatments. Furthermore, the pattern of parasitism by T. deion in the 36 four-egg patches treatment was the most aggregated among the three species, suggesting a more thorough searching pattern. In contrast, T. pretiosum had the least aggregated pattern of parasitism and therefore may have used a more random foraging pattern. PMID:20673123

Grieshop, Matthew J.; Flinn, Paul W.; Nechols, James R.

2010-01-01

379

Ample genetic variation but no evidence for genotype specificity in an all-parthenogenetic host-parasitoid interaction.  

PubMed

Antagonistic coevolution between hosts and parasites can result in negative frequency-dependent selection and may thus be an important mechanism maintaining genetic variation in populations. Negative frequency-dependence emerges readily if interactions between hosts and parasites are genotype-specific such that no host genotype is most resistant to all parasite genotypes, and no parasite genotype is most infective on all hosts. Although there is increasing evidence for genotype specificity in interactions between hosts and pathogens or microparasites, the picture is less clear for insect host-parasitoid interactions. Here, we addressed this question in the black bean aphid (Aphis fabae) and its most important parasitoid Lysiphlebus fabarum. Because both antagonists are capable of parthenogenetic reproduction, this system allows for powerful tests of genotype x genotype interactions. Our test consisted of exposing multiple host clones to different parthenogenetic lines of parasitoids in all combinations, and this experiment was repeated with animals from four different sites. All aphids were free of endosymbiotic bacteria known to increase resistance to parasitoids. We observed ample genetic variation for host resistance and parasitoid infectivity, but there was no significant host clone x parasitoid line interaction, and this result was consistent across the four sites. Thus, there is no evidence for genotype specificity in the interaction between A. fabae and L. fabarum, suggesting that the observed variation is based on rather general mechanisms of defence and attack. PMID:20074305

Sandrock, C; Gouskov, A; Vorburger, C

2010-03-01

380

Parasite-induced Host Mortality: Indirect Evidence From a Long-term Study  

Microsoft Academic Search

A long-term field study of a perturbed hosthelminth system provides indirect evidence that a long-lived swimbladder nematode, Cystidicola farionis, induces mortality of Arctic charr, Salvelinus alpinus. The prevalence and abundance of this parasite has changed little over the period from 1987 to 1999. The cumulative numbers of L3-stage larvae steadily increased with increasing host age, indicating a continuous exposure to

Rune Knudsen; Per-Arne Amundsen; Anders Klemetsen

2002-01-01