Testing for thermal acclimation in zoospores of an amphibian pathogen.

Thermal acclimation effects on locomotory performance have been widely documented for macroscopic organisms, but such responses remain largely unexplored in microorganisms. Metabolic theory of ecology (MTE) predicts faster responses in smaller organisms, with potential consequences for host-parasite interactions in variable temperature environments. We investigated thermal acclimation effects on zoospores of the amphibian fungal pathogen Batrachochytrium dendrobatidis (Bd), quantifying (1) thermal performance for maximum zoospore velocity and (2) high temperatures needed to immobilize 50% (CT50max) or 100% (CT100max) of zoospores.

Dynamic effects of thermal acclimation on chytridiomycosis infection intensity and transmission potential in .

The pandemic amphibian pathogen (Bd) can cause more severe infections with variable temperatures owing to delays in host thermal acclimation following temperature shifts. However, little is known about the timing of these acclimation effects or their consequences for Bd transmission. We measured how thermal acclimation affects Bd infection in , using a timing-of-exposure treatment to investigate acclimation effect persistence following a temperature shift.

Canopy coverage, light, and moisture affect thermoregulatory trade-offs in an amphibian breeding habitat.

When amphibians thermoregulate, they face a fundamental trade-off between the ability to maintain activity and an increased rate of dehydration at higher temperatures. Canopy coverage affects both the thermal and hydric conditions of the environment and can therefore influence amphibian thermoregulation. Frogs require proper conditions to thermoregulate to successfully grow, survive, and reproduce.

Glove decontamination procedures to prevent pathogen and DNA cross-contamination among frogs.

Working with aquatic organisms often requires handling multiple individuals in a single session, potentially resulting in cross-contamination by live pathogens or DNA. Most researchers address this problem by disposing of gloves between animals. However, this generates excessive waste and may be impractical for processing very slippery animals that might be easier to handle with cotton gloves.

Large-scale spatial drivers of avian schistosomes in Northern Michigan inland lakes.

Avian schistosomes are snail-borne trematode parasites ( spp.) that can cause a nasty skin rash in humans when their cercariae mistake us for their normal bird hosts. We sought to investigate drivers of the spatial distribution of cercaria abundance throughout Northern Michigan lakes.

Using Metabolic Theory to Describe Temperature and Thermal Acclimation Effects on Parasitic Infection.

AbstractPredicting temperature effects on species interactions can be challenging, especially for parasitism, where it is difficult to experimentally separate host and parasite thermal performance curves. Prior authors proposed a possible solution based on the metabolic theory of ecology (MTE), using MTE-based equations to describe the thermal mismatch between host and parasite performance curves and account for thermal acclimation responses. Here, we use published infection data, supplemented with experiments measuring metabolic responses to temperature in each species, to show that this modeling framework can successfully describe thermal acclimation effects on two different stages of infection in a tadpole-trematode system.

Hot and sour: parasite adaptations to honeybee body temperature and pH.

Host temperature and gut chemistry can shape resistance to parasite infection. Heat and acidity can limit trypanosomatid infection in warm-blooded hosts and could shape infection resistance in insects as well. The colony-level endothermy and acidic guts of social bees provide unique opportunities to study how temperature and acidity shape insect-parasite associations.

Pesticides alter ecosystem respiration via phytoplankton abundance and community structure: Effects on the carbon cycle?

Freshwater systems are critical to life on earth, yet they are threatened by the increasing rate of synthetic chemical pollution. Current predictions of the effects of synthetic chemicals on freshwater ecosystems are hampered by the sheer number of chemical contaminants entering aquatic systems, the diversity of organisms inhabiting these systems, the myriad possible direct and indirect effects resulting from these combinations, and uncertainties concerning how contaminants might alter ecosystem metabolism via changes in biodiversity. To address these knowledge gaps, we conducted a mesocosm experiment that elucidated the responses of ponds composed of phytoplankton and zooplankton to standardized concentrations of 12 pesticides, nested within four pesticide classes, and two pesticide types.

Temperature and mass scaling affect cutaneous and pulmonary respiratory performance in a diving frog.

Global climate change is altering patterns of temperature variation, with unpredictable consequences for species and ecosystems. The Metabolic Theory of Ecology (MTE) provides a powerful framework for predicting climate change impacts on ectotherm metabolic performance. MTE postulates that physiological and ecological processes are limited by organism metabolic rates, which scale predictably with body mass and temperature.

Consistent effects of pesticides on community structure and ecosystem function in freshwater systems.

Predicting ecological effects of contaminants remains challenging because of the sheer number of chemicals and their ambiguous role in biodiversity-ecosystem function relationships. We evaluate responses of experimental pond ecosystems to standardized concentrations of 12 pesticides, nested in four pesticide classes and two pesticide types. We show consistent effects of herbicides and insecticides on ecosystem function, and slightly less consistent effects on community composition.

Caldicellulosiruptor bescii Adheres to Polysaccharides via a Type IV Pilin-Dependent Mechanism.

Biological hydrolysis of cellulose above 70°C involves microorganisms that secrete free enzymes and deploy separate protein systems to adhere to their substrate. Strongly cellulolytic is one such extreme thermophile, which deploys modular, multifunctional carbohydrate-acting enzymes to deconstruct plant biomass. Additionally, also encodes noncatalytic carbohydrate binding proteins, which likely evolved as a mechanism to compete against other heterotrophs in carbon-limited biotopes that these bacteria inhabit.

Direct onshore wind predicts daily swimmer's itch (avian schistosome) incidence at a Michigan beach.

Swimmer's itch (SI) is a painful rash caused by skin penetration by free-swimming infectious cercariae of avian schistosomes, snail-borne helminth parasites related to the causative agents of human schistosomiasis. The goal of this study was to determine if commonly collected environmental data could be used to predict daily fluctuations in SI incidence at an inland beach in northwestern Michigan. Lifeguards collected daily data over four summers, including the number of self-reported SI cases, total swimmers, water temperature, wind speed and wind direction.

Temperature dependence of parasitic infection and gut bacterial communities in bumble bees.

High temperatures (e.g., fever) and gut microbiota can both influence host resistance to infection.

Shifts in temperature influence how Batrachochytrium dendrobatidis infects amphibian larvae.

Many climate change models predict increases in frequency and magnitude of temperature fluctuations that might impact how ectotherms are affected by disease. Shifts in temperature might especially affect amphibians, a group with populations that have been challenged by several pathogens. Because amphibian hosts invest more in immunity at warmer than cooler temperatures and parasites might acclimate to temperature shifts faster than hosts (creating lags in optimal host immunity), researchers have hypothesized that a temperature shift from cold-to-warm might result in increased amphibian sensitivity to pathogens, whereas a shift from warm-to-cold might result in decreased sensitivity.

Thermal acclimation has little effect on tadpole resistance to Batrachochytrium dendrobatidis.

Given that climate change is predicted to alter patterns of temperature variability, it is important to understand how shifting temperatures might influence species interactions, including parasitism. Predicting thermal effects on species interactions is complicated, however, because the temperature-dependence of the interaction depends on the thermal responses of both interacting organisms, which can also be influenced by thermal acclimation, a process by which organisms adjust their physiologies in response to a temperature change. We tested for thermal acclimation effects on Lithobates clamitans tadpole susceptibility to the fungus Batrachochytrium dendrobatidis (Bd) by acclimating tadpoles to 1 of 3 temperatures, moving them to 1 of 5 performance temperatures at which we exposed them to Bd, and measuring Bd loads on tadpoles post-exposure.

Effects of pesticides on exposure and susceptibility to parasites can be generalised to pesticide class and type in aquatic communities.

Pesticide pollution can alter parasite transmission, but scientists are unaware if effects of pesticides on parasite exposure and host susceptibility (i.e. infection risk given exposure) can be generalised within a community context.

Temperature-mediated inhibition of a bumblebee parasite by an intestinal symbiont.

Competition between organisms is often mediated by environmental factors, including temperature. In animal intestines, nonpathogenic symbionts compete physically and chemically against pathogens, with consequences for host infection. We used metabolic theory-based models to characterize differential responses to temperature of a bacterial symbiont and a co-occurring trypanosomatid parasite of bumblebees, which regulate body temperature during flight and incubation.

pH-mediated inhibition of a bumble bee parasite by an intestinal symbiont.

Gut symbionts can augment resistance to pathogens by stimulating host-immune responses, competing for space and nutrients, or producing antimicrobial metabolites. Gut microbiota of social bees, which pollinate many crops and wildflowers, protect hosts against diverse infections and might counteract pathogen-related bee declines. Bumble bee gut microbiota, and specifically abundance of Lactobacillus 'Firm-5' bacteria, can enhance resistance to the trypanosomatid parasite Crithidia bombi.

Agrochemicals increase risk of human schistosomiasis by supporting higher densities of intermediate hosts.

Schistosomiasis is a snail-borne parasitic disease that ranks among the most important water-based diseases of humans in developing countries. Increased prevalence and spread of human schistosomiasis to non-endemic areas has been consistently linked with water resource management related to agricultural expansion. However, the role of agrochemical pollution in human schistosome transmission remains unexplored, despite strong evidence of agrochemicals increasing snail-borne diseases of wildlife and a projected 2- to 5-fold increase in global agrochemical use by 2050.

Thermal Performance Curves and the Metabolic Theory of Ecology-A Practical Guide to Models and Experiments for Parasitologists.

Climate change will affect host-parasite dynamics in complex ways. The development of forecast models is necessary for proactive disease management, but past studies have frequently reported thermal performance data in idiosyncratic ways that have limited use for parameterizing thermal host-parasite models. Development of improved forecast models will require strong collaborations between experimental parasitologists and disease modelers.

Bottom-up and trait-mediated effects of resource quality on amphibian parasitism.

Leaf litter subsidies are important resources for aquatic consumers like tadpoles and snails, causing bottom-up effects on wetland ecosystems. Recent studies have shown that variation in litter nutritional quality can be as important as litter quantity in driving these bottom-up effects. Resource subsidies likely also have indirect and trait-mediated effects on predation and parasitism, but these potential effects remain largely unexplored.

Ontogenetic changes in sensitivity to nutrient limitation of tadpole growth.

According to ecological stoichiometry (ES), the growth of a consumer with abundant resources should increase as body and resource stoichiometry become more similar. However, for organisms with complex life cycles involving distinct changes in biology, nutrient demands might change in response to ontogenetic changes in body stoichiometry. Tadpole growth and development has been found to be largely nitrogen (N) limited, as predicted for organisms developing N-rich tissues like muscle.

Effect of Irradiation on Tumor Microenvironment and Bone Marrow Cell Migration in a Preclinical Tumor Model.

Purpose: To characterize the tumor microenvironment after standard radiation therapy (SRT) and pulsed radiation therapy (PRT) in Lewis lung carcinoma (LLC) allografts.

Methods And Materials: Subcutaneous LLC tumors were established in C57BL/6 mice. Standard RT or PRT was given at 2 Gy/d for a total dose of 20 Gy using a 5 days on, 2 days off schedule to mimic clinical delivery.

Host and parasite thermal acclimation responses depend on the stage of infection.

Global climate change is expected to alter patterns of temperature variability, which could influence species interactions including parasitism. Species interactions can be difficult to predict in variable-temperature environments because of thermal acclimation responses, i.e.