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.

The impact of environmental infections (parasites) on MS activity

2011 ◽  
Vol 17 (10) ◽  
pp. 1162-1169 ◽  
Author(s):  
Jorge Correale ◽  
Mauricio F Farez
Keyword(s):  
Disease Onset ◽  
Epidemiological Data ◽  
Molecular Data ◽  
Protective Role ◽  
Host Parasite ◽  
Developed World ◽  
The Impact ◽  
Specific Parasite ◽  
Parasite Exposure

MS incidence has significantly increased during the second half of the 20th century, generating considerable interest in analyzing the basis for this rise in the developed world. Particular emphasis is being placed on the role infections might play in exacerbating or preventing disease onset. Epidemiological data suggest that improvement in sanitation conditions and reduced exposure to infection might explain, at least in part, these changes. The hygiene hypothesis is not new and is currently used to explain the increasing incidence of allergies and other autoimmune diseases. Because helminths are powerful modulators of host immunity, some authors hypothesize that reduced parasite exposure due to improved hygiene conditions may favor MS development. We discuss epidemiological, experimental, clinical and molecular data supporting the protective role of helminthes against MS. Better understanding of host–parasite interactions caused by specific parasite molecules with immunomodulatory effects will help combat allergies and autoimmune disease without the price of untoward infection as a side-effect.

scholarly journals Cost of a deprived environment – increased intraspecific aggression and susceptibility to pathogen infections

2020 ◽  
Vol 223 (20) ◽  
pp. jeb229450
Author(s):  
Numair Masud ◽  
Amy Ellison ◽  
Edward C. Pope ◽  
Jo Cable
Keyword(s):  
Stress Responses ◽  
Environmental Enrichment ◽  
Intraspecific Aggression ◽  
Limited Data ◽  
Susceptibility To Infection ◽  
Physiological Cost ◽  
Aquatic Vertebrates ◽  
Biological Cost ◽  
Host Parasite ◽  
The Impact

ABSTRACTA lack of environmental enrichment can be severely detrimental to animal welfare. For terrestrial species, including humans, barren environments are associated with reduced cognitive function and increased stress responses and pathology. Despite a clear link between increased stress and reduced immune function, uncertainty remains on how enrichment might influence susceptibility to disease. For aquatic vertebrates, we are only now beginning to assess enrichment needs. Enrichment deprivation in fish has been linked to increased stress responses, agonistic behaviour, physiological changes and reduced survival. Limited data exist, however, on the impact of enrichment on disease resistance in fish, despite infectious diseases being a major challenge for global aquaculture. Here, using a model vertebrate host–parasite system, we investigated the impact of enrichment deprivation on susceptibility to disease, behaviour and physiology. Fish in barren tanks showed significantly higher infection burdens compared with those in enriched enclosures and they also displayed increased intraspecific aggression behaviour. Infections caused hosts to have significantly increased standard metabolic rates compared with uninfected conspecifics, but this did not differ between enriched and barren tanks. This study highlights the universal physiological cost of parasite infection and the biological cost (increased susceptibility to infection and increased aggression) of depriving captive animals of environmental enrichment.

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.

Emotions and health: The impact of emotions, emotions regulation, music, and acculturation on health

2008 ◽  
Vol 16 (3) ◽  
pp. 112-115 ◽  
Author(s):  
Stephan Bongard ◽  
Volker Hodapp ◽  
Sonja Rohrmann
Keyword(s):  
Stress Responses ◽  
Physiological Stress ◽  
Anger Expression ◽  
Domain Specific ◽  
Cardiovascular Stress ◽  
Expression Behavior ◽  
Cardio Vascular ◽  
And Coping ◽  
Relationship Of ◽  
The Impact

Abstract. Our unit investigates the relationship of emotional processes (experience, expression, and coping), their physiological correlates and possible health outcomes. We study domain specific anger expression behavior and associated cardio-vascular loads and found e.g. that particularly an open anger expression at work is associated with greater blood pressure. Furthermore, we demonstrated that women may be predisposed for the development of certain mental disorders because of their higher disgust sensitivity. We also pointed out that the suppression of negative emotions leads to increased physiological stress responses which results in a higher risk for cardiovascular diseases. We could show that relaxation as well as music activity like singing in a choir causes increases in the local immune parameter immunoglobuline A. Finally, we are investigating connections between migrants’ strategy of acculturation and health and found e.g. elevated cardiovascular stress responses in migrants when they where highly adapted to the German culture.

Childbirth and Posttraumatic Stress Responses

2006 ◽  
Vol 22 (4) ◽  
pp. 259-267 ◽  
Author(s):  
Eelco Olde ◽  
Rolf J. Kleber ◽  
Onno van der Hart ◽  
Victor J.M. Pop
Keyword(s):  
Posttraumatic Stress Disorder ◽  
Posttraumatic Stress ◽  
Stress Responses ◽  
Rating Scales ◽  
Rating Scale ◽  
Stress Disorder ◽  
Traumatic Experience ◽  
Event Scale ◽  
Self Rating ◽  
The Impact

Childbirth has been identified as a possible traumatic experience, leading to traumatic stress responses and even to the development of posttraumatic stress disorder (PTSD). The current study investigated the psychometric properties of the Dutch version of the Impact of Event Scale-Revised (IES-R) in a group of women who recently gave birth (N = 435). In addition, a comparison was made between the original IES and the IES-R. The scale showed high internal consistency (α = 0.88). Using confirmatory factor analysis no support was found for a three-factor structure of an intrusion, an avoidance, and a hyperarousal factor. Goodness of fit was only reasonable, even after fitting one intrusion item on the hyperarousal scale. The IES-R correlated significantly with scores on depression and anxiety self-rating scales, as well as with scores on a self-rating scale of posttraumatic stress disorder. Although the IES-R can be used for studying posttraumatic stress reactions in women who recently gave birth, the original IES proved to be a better instrument compared to the IES-R. It is concluded that adding the hyperarousal scale to the IES-R did not make the scale stronger.

scholarly journals Arginine Decarboxylase Is Essential for Pneumococcal Stress Responses

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 286
Author(s):  
Mary Frances Nakamya ◽  
Moses B. Ayoola ◽  
Leslie A. Shack ◽  
Mirghani Mohamed ◽  
Edwin Swiatlo ◽  
...  
Keyword(s):  
Stress Responses ◽  
Critical Role ◽  
Acid Stress ◽  
Arginine Decarboxylase ◽  
Arginine Deiminase ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Opportunistic Human Pathogen ◽  
Thiol Peroxidase ◽  
The Impact

Polyamines such as putrescine, cadaverine, and spermidine are small cationic molecules that play significant roles in cellular processes, including bacterial stress responses and host–pathogen interactions. Streptococcus pneumoniae is an opportunistic human pathogen, which causes several diseases that account for significant morbidity and mortality worldwide. As it transits through different host niches, S. pneumoniae is exposed to and must adapt to different types of stress in the host microenvironment. We earlier reported that S. pneumoniae TIGR4, which harbors an isogenic deletion of an arginine decarboxylase (ΔspeA), an enzyme that catalyzes the synthesis of agmatine in the polyamine synthesis pathway, has a reduced capsule. Here, we report the impact of arginine decarboxylase deletion on pneumococcal stress responses. Our results show that ΔspeA is more susceptible to oxidative, nitrosative, and acid stress compared to the wild-type strain. Gene expression analysis by qRT-PCR indicates that thiol peroxidase, a scavenger of reactive oxygen species and aguA from the arginine deiminase system, could be important for peroxide stress responses in a polyamine-dependent manner. Our results also show that speA is essential for endogenous hydrogen peroxide and glutathione production in S. pneumoniae. Taken together, our findings demonstrate the critical role of arginine decarboxylase in pneumococcal stress responses that could impact adaptation and survival in the host.

scholarly journals A New Approach for Design Optimization and Parametric Analysis of Symmetric Compound Parabolic Concentrator for Photovoltaic Applications

2021 ◽  
Vol 13 (9) ◽  
pp. 4606
Author(s):  
Faisal Masood ◽  
Perumal Nallagownden ◽  
Irraivan Elamvazuthi ◽  
Javed Akhter ◽  
Mohammad Azad Alam
Keyword(s):  
Parametric Analysis ◽  
Concentration Ratio ◽  
Synergistic Effects ◽  
Geometric Optimization ◽  
Design Parameters ◽  
Imaging Device ◽  
Compound Parabolic Concentrator ◽  
Photovoltaic Applications ◽  
Half Angle ◽  
The Impact

A compound parabolic concentrator (CPC) is a non-imaging device generally used in PV, thermal, or PV/thermal hybrid systems for the concentration of solar radiation on the target surface. This paper presents the geometric design, statistical modeling, parametric analysis, and geometric optimization of a two-dimensional low concentration symmetric compound parabolic concentrator for potential use in building-integrated and rooftop photovoltaic applications. The CPC was initially designed for a concentration ratio of “2×” and an acceptance half-angle of 30°. A MATLAB code was developed in house to provoke the CPC reflector’s profile. The height, aperture width, and concentration ratios were computed for different acceptance half-angles and receiver widths. The interdependence of optical concentration ratio and acceptance half-angle was demonstrated for a wide span of acceptance half-angles. The impact of the truncation ratio on the geometric parameters was investigated to identify the optimum truncation position. The profile of truncated CPC for different truncation positions was compared with full CPC. A detailed statistical analysis was performed to analyze the synergistic effects of independent design parameters on the responses using the response surface modeling approach. A set of optimized design parameters was obtained by establishing specified optimization criteria. A 50% truncated CPC with an acceptance half-angle of 21.58° and receiver width of 193.98 mm resulted in optimum geometric dimensions.

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