scholarly journals Genetic variation in the cellular response of Daphnia magna (Crustacea: Cladocera) to its bacterial parasite

2010 ◽  
Vol 277 (1698) ◽  
pp. 3291-3297 ◽  
Author(s):  
Stuart K. J. R. Auld ◽  
Jennifer A. Scholefield ◽  
Tom J. Little
Keyword(s):  
Genetic Variation ◽  
Daphnia Magna ◽  
Cellular Response ◽  
Cell Types ◽  
Parasite Fitness ◽  
Pasteuria Ramosa ◽  
Cellular Immune ◽  
Genetically Determined ◽  
Host Parasite ◽  
Parasite Exposure

Linking measures of immune function with infection, and ultimately, host and parasite fitness is a major goal in the field of ecological immunology. In this study, we tested for the presence and timing of a cellular immune response in the crustacean Daphnia magna following exposure to its sterilizing endoparasite Pasteuria ramosa . We found that D. magna possesses two cell types circulating in the haemolymph: a spherical one, which we call a granulocyte and an irregular-shaped amoeboid cell first described by Metchnikoff over 125 years ago. Daphnia magna mounts a strong cellular response (of the amoeboid cells) just a few hours after parasite exposure. We further tested for, and found, considerable genetic variation for the magnitude of this cellular response. These data fostered a heuristic model of resistance in this naturally coevolving host–parasite interaction. Specifically, the strongest cellular responses were found in the most susceptible hosts, indicating resistance is not always borne from a response that destroys invading parasites, but rather stems from mechanisms that prevent their initial entry. Thus, D. magna may have a two-stage defence—a genetically determined barrier to parasite establishment and a cellular response once establishment has begun.

scholarly journals The infection rate of Daphnia magna by Pasteuria ramosa conforms with the mass-action principle

2003 ◽  
Vol 131 (2) ◽  
pp. 957-966 ◽  
Author(s):  
R. R. REGOES ◽  
J. W. HOTTINGER ◽  
L. SYGNARSKI ◽  
D. EBERT
Keyword(s):  
Daphnia Magna ◽  
Infection Rate ◽  
Infection Process ◽  
Action Principle ◽  
Mass Action ◽  
Infection Model ◽  
Susceptibility To Infection ◽  
Pasteuria Ramosa ◽  
Simple Mass ◽  
Host Parasite

In simple epidemiological models that describe the interaction between hosts with their parasites, the infection process is commonly assumed to be governed by the law of mass action, i.e. it is assumed that the infection rate depends linearly on the densities of the host and the parasite. The mass-action assumption, however, can be problematic if certain aspects of the host–parasite interaction are very pronounced, such as spatial compartmentalization, host immunity which may protect from infection with low doses, or host heterogeneity with regard to susceptibility to infection. As deviations from a mass-action infection rate have consequences for the dynamics of the host–parasite system, it is important to test for the appropriateness of the mass-action assumption in a given host–parasite system. In this paper, we examine the relationship between the infection rate and the parasite inoculum for the water flee Daphnia magna and its bacterial parasite Pasteuria ramosa. We measured the fraction of infected hosts after exposure to 14 different doses of the parasite. We find that the observed relationship between the fraction of infected hosts and the parasite dose is largely consistent with an infection process governed by the mass-action principle. However, we have evidence for a subtle but significant deviation from a simple mass-action infection model, which can be explained either by some antagonistic effects of the parasite spores during the infection process, or by heterogeneity in the hosts' susceptibility with regard to infection.

scholarly journals Cytokine responses to two common respiratory pathogens in children are dependent on interleukin-1β

2017 ◽  
Vol 3 (4) ◽  
pp. 00025-2017 ◽  
Author(s):  
Alice C-H. Chen ◽  
Yang Xi ◽  
Melanie Carroll ◽  
Helen L. Petsky ◽  
Samantha J. Gardiner ◽  
...  
Keyword(s):  
Cellular Response ◽  
Mononuclear Cells ◽  
Cell Types ◽  
Respiratory Pathogens ◽  
Peripheral Blood Mononuclear ◽  
Multiple Cell ◽  
Ifn Γ ◽  
High Concentrations ◽  
Cellular Immune ◽  
And Control

Protracted bacterial bronchitis (PBB) in young children is a common cause of prolonged wet cough and may be a precursor to bronchiectasis in some children. Although PBB and bronchiectasis are both characterised by neutrophilic airway inflammation and a prominent interleukin (IL)-1β signature, the contribution of the IL-1β pathway to host defence is not clear.This study aimed to compare systemic immune responses against common pathogens in children with PBB, bronchiectasis and control children and to determine the importance of the IL-1β pathway.Non-typeable Haemophilus influenzae (NTHi) stimulation of peripheral blood mononuclear cells (PBMCs) from control subjects (n=20), those with recurrent PBB (n=20) and bronchiectasis (n=20) induced high concentrations of IL-1β, IL-6, interferon (IFN)-γ and IL-10. Blocking with an IL-1 receptor antagonist (IL-1Ra) modified the cellular response to pathogens, inhibiting cytokine synthesis by NTHi-stimulated PBMCs and rhinovirus-stimulated PBMCs (in a separate PBB cohort). Inhibition of IFN-γ production by IL-1Ra was observed across multiple cell types, including CD3+ T cells and CD56+ NK cells.Our findings highlight the extent to which IL-1β regulates the cellular immune response against two common respiratory pathogens. While blocking the IL-1β pathway has the potential to reduce inflammation, this may come at the cost of protective immunity against NTHi and rhinovirus.

scholarly journals Host age modulates within-host parasite competition

2015 ◽  
Vol 11 (5) ◽  
pp. 20150131 ◽  
Author(s):  
Rony Izhar ◽  
Jarkko Routtu ◽  
Frida Ben-Ami
Keyword(s):  
Evolutionary Dynamics ◽  
Parasite Prevalence ◽  
Host Age ◽  
Individual Level ◽  
Pasteuria Ramosa ◽  
Age Dependent ◽  
The Individual ◽  
Host Parasite ◽  
Parasite Exposure ◽  
Age At Exposure

In many host populations, one of the most striking differences among hosts is their age. While parasite prevalence differences in relation to host age are well known, little is known on how host age impacts ecological and evolutionary dynamics of diseases. Using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa , we examined how host age at exposure influences within-host parasite competition and virulence. We found that multiply-exposed hosts were more susceptible to infection and suffered higher mortality than singly-exposed hosts. Hosts oldest at exposure were least often infected and vice versa. Furthermore, we found that in young multiply-exposed hosts competition was weak, allowing coexistence and transmission of both parasite clones, whereas in older multiply-exposed hosts competitive exclusion was observed. Thus, age-dependent parasite exposure and host demography (age structure) could together play an important role in mediating parasite evolution. At the individual level, our results demonstrate a previously unnoticed interaction of the host's immune system with host age, suggesting that the specificity of immune function changes as hosts mature. Therefore, evolutionary models of parasite virulence might benefit from incorporating age-dependent epidemiological parameters.

scholarly journals Starvation reveals the cause of infection-induced castration and gigantism

2014 ◽  
Vol 281 (1792) ◽  
pp. 20141087 ◽  
Author(s):  
Clayton E. Cressler ◽  
William A. Nelson ◽  
Troy Day ◽  
Edward McCauley
Keyword(s):  
Life History ◽  
Energy Budget ◽  
Life History Variation ◽  
Starvation Stress ◽  
Parasite Fitness ◽  
Pasteuria Ramosa ◽  
Investment In Reproduction ◽  
Growth Energy ◽  
Host Parasite

Parasites often induce life-history changes in their hosts. In many cases, these infection-induced life-history changes are driven by changes in the pattern of energy allocation and utilization within the host. Because these processes will affect both host and parasite fitness, it can be challenging to determine who benefits from them. Determining the causes and consequences of infection-induced life-history changes requires the ability to experimentally manipulate life history and a framework for connecting life history to host and parasite fitness. Here, we combine a novel starvation manipulation with energy budget models to provide new insights into castration and gigantism in the Daphnia magna – Pasteuria ramosa host–parasite system. Our results show that starvation primarily affects investment in reproduction, and increasing starvation stress reduces gigantism and parasite fitness without affecting castration. These results are consistent with an energetic structure where the parasite uses growth energy as a resource. This finding gives us new understanding of the role of castration and gigantism in this system, and how life-history variation will affect infection outcome and epidemiological dynamics. The approach of combining targeted life-history manipulations with energy budget models can be adapted to understand life-history changes in other disease systems.

scholarly journals The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model

PLoS Genetics ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. e1006596 ◽  
Author(s):  
Gilberto Bento ◽  
Jarkko Routtu ◽  
Peter D. Fields ◽  
Yann Bourgeois ◽  
Louis Du Pasquier ◽  
...  
Keyword(s):  
Daphnia Magna ◽  
Genetic Basis ◽  
Pasteuria Ramosa ◽  
Host Parasite

scholarly journals Synergistic effects of dual parasitism in Daphnia magna under nutrient limitation

2017 ◽  
Vol 147 (1) ◽  
Author(s):  
Lien Reyserhove ◽  
Koenraad Muylaert ◽  
Isabel Vanoverberghe ◽  
Ellen Decaestecker
Keyword(s):  
Nutrient Limitation ◽  
Daphnia Magna ◽  
Stress Responses ◽  
Synergistic Effects ◽  
Energy Budgets ◽  
Fat Cell ◽  
Host Parasite ◽  
White Fat ◽  
The Impact ◽  
Parasite Exposure

Human-induced increases in the bioavailability of carbon (C), nitrogen (N) and phosphorus (P) have the potential to alter the context for host-parasite dynamics in aquatic ecosystems. Given that both eutrophication and infectious diseases are becoming more prominent, it is essential to disentangle the factors that determine virulence expression in keystone grazers. Here, we focus on the impact of nutrient limitation in single versus dual parasite exposure in the water flea Daphnia magna (Crustacea, Branchiopoda). For this, we fed specimens of D. magna with algae differing in C:N:P ratios and exposed them to two virulent parasites, Pasteuria ramosa (bacteria) and the agent causing White Fat Cell (WFCD, unknown classification), both in single and dual parasite exposure treatments. Exposure to the two parasites synergistically reduced host survival, mainly driven by WFCD exposure, especially under severe nutrient limitation. Under these conditions individuals of D. magna began reproducing earlier, which resulted in a higher reproductive output upon dual parasite exposure. We here discuss these results within the framework of host stress responses, nutrient allocation and energy budgets, and conclude that the way food quality interferes with host-parasite interactions varies, depending on the parasite species involved, the nutrient requirements of all actors and the trait investigated.

Production and Analysis of High Resolution Polymer Replicas of Fibrillar Collagen

1999 ◽  
Vol 5 (S2) ◽  
pp. 398-399
Author(s):  
P. Sims ◽  
B. Todd ◽  
S. Eppell ◽  
T. Li ◽  
K. Park ◽  
...  
Keyword(s):  
Cellular Response ◽  
Physical Nature ◽  
Cell Types ◽  
Artificial Substrates ◽  
Adherent Cell ◽  
Fibrillar Collagen ◽  
New Materials ◽  
Substrate Interactions ◽  
Number Of Factors ◽  
Cell Substrate

Adherent cells generally construct the immediate substrate upon which they reside. This may occur via synthesis and secretion of new materials and/or by rearrangement and modification of existing substrate. The response of adherent cell types to an existing substrate can be influenced by a number of factors which include both the chemical and physical nature of the substrate. Cell adhesion, proliferation, differentiation and death can all be substrate dependent. Much effort has been directed toward chemical modification of substrates to regulate one or more of the parameters noted above. A significant, but somewhat smaller, degree of attention has been paid to the effects of the topography and microtopography on the cell response to substrate materials. Studies to date strongly suggest the topography is a significant factor in cell-substrate interactions. As noted above, it is most probable that both the chemistry and the structure of a substrate simultaneously influence the cellular response. However we wished to determine, particularly for artificial substrates, the role which microtopography can play in cell-substrate interactions.

scholarly journals Mechanisms in allergic airway inflammation – lessons from studies in the mouse

2008 ◽  
Vol 10 ◽  
Author(s):  
Bennett O.V. Shum ◽  
Michael S. Rolph ◽  
William A. Sewell
Keyword(s):  
Inflammatory Response ◽  
Airway Inflammation ◽  
Cellular Response ◽  
Allergic Airway Inflammation ◽  
Cell Types ◽  
Therapeutic Agents ◽  
Chronic Inflammatory Disease ◽  
Pathological Feature ◽  
Cytokines And Chemokines ◽  
Novel Therapeutic

Asthma is a chronic inflammatory disease of the airways, involving recurrent episodes of airway obstruction and wheezing. A common pathological feature in asthma is the presence of a characteristic allergic airway inflammatory response involving extensive leukocyte infiltration, mucus overproduction and airway hyper-reactivity. The pathogenesis of allergic airway inflammation is complex, involving multiple cell types such as T helper 2 cells, regulatory T cells, eosinophils, dendritic cells, mast cells, and parenchymal cells of the lung. The cellular response in allergic airway inflammation is controlled by a broad range of bioactive mediators, including IgE, cytokines and chemokines. The asthmatic allergic inflammatory response has been a particular focus of efforts to develop novel therapeutic agents. Animal models are widely used to investigate inflammatory mechanisms. Although these models are not perfect replicas of clinical asthma, such studies have led to the development of numerous novel therapeutic agents, of which some have already been successful in clinical trials.

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