20 research outputs found
Disease Dynamics in a Specialized Parasite of Ant Societies
Coevolution between ant colonies and their rare specialized parasites are intriguing, because lethal infections of workers may correspond to tolerable chronic diseases of colonies, but the parasite adaptations that allow stable coexistence with ants are virtually unknown. We explore the trade-offs experienced by Ophiocordyceps parasites manipulating ants into dying in nearby graveyards. We used field data from Brazil and Thailand to parameterize and fit a model for the growth rate of graveyards. We show that parasite pressure is much lower than the abundance of ant cadavers suggests and that hyperparasites often castrate Ophiocordyceps. However, once fruiting bodies become sexually mature they appear robust. Such parasite life-history traits are consistent with iteroparity– a reproductive strategy rarely considered in fungi. We discuss how tropical habitats with high biodiversity of hyperparasites and high spore mortality has likely been crucial for the evolution and maintenance of iteroparity in parasites with low dispersal potential
Climate change and weather related impacts
In order to address the contributions of GNSS to monitor climate change caused by increase in temperature, a distinction between weather and climate on one hand, and climate variability and climate change on the other hand is essential
Effects of antidepressants on the performance in the forced swim test of two psychogenetically selected lines of rats that differ in coping strategies to aversive conditions
Psychopharmacology (Berl). 2010 Sep;211(4):403-14. Epub 2010 Jun 30.
Effects of antidepressants on the performance in the forced swim test of two
psychogenetically selected lines of rats that differ in coping strategies to
aversive conditions.
Piras G, Giorgi O, Corda MG.
Department of Toxicology, University of Cagliari, Via Ospedale 72, 09124,
Cagliari, Italy.
INTRODUCTION: The selective breeding of Roman low-avoidance (RLA) and
high-avoidance (RHA) rats for, respectively, poor versus rapid acquisition of
active avoidance in a shuttle-box has produced two phenotypes that differ
drastically in the reactivity to stressful stimuli: in tests used to assess
emotionality, RLA rats display passive ("reactive") coping and robust
hypothalamus-pituitary-adrenal (HPA) axis reactivity, whereas RHA rats show
proactive coping and blunted HPA axis responses. The behavioral and
neuroendocrine traits that distinguish these lines suggest that RLA rats may be
prone, whereas RHA rats may be resistant to develop depression-like behavior when
exposed to stressful experimental conditions.
OBJECTIVE AND METHODS: To evaluate the performance of the Roman lines in the
forced swim test, immobility, climbing, and swimming were assessed under baseline
conditions (i.e., pretest in naĂŻve animals or test after the administration of
vehicle), and after subacute treatment with desipramine, fluoxetine, and
chlorimipramine.
RESULTS: Under baseline conditions, RLA rats displayed greater immobility and
fewer climbing counts than RHA rats. In RLA rats, desipramine, fluoxetine, and
chlorimipramine decreased immobility; moreover, desipramine and chlorimipramine
increased climbing, whereas fluoxetine increased swimming. In RHA rats, none of
these drugs affected immobility, swimming, or climbing.
CONCLUSIONS: RLA and RHA rats represent two divergent phenotypes respectively
susceptible and resistant to display depression-like behavior in the forced swim
test. Hence, comparative studies in these lines may help to develop novel working
hypotheses on the relationships among genotype, temperament traits, and neural
mechanisms underlying the vulnerability or resistance to stress-induced
depression in humans.
PMID: 20589496 [PubMed - indexed for MEDLINE