Exposure to mercury reduces cold tolerance in the springtail Folsomia candida

The Resilience of Polar Collembola (Springtails) in a Changing Climate

Assessing the resilience of polar biota to climate change is essential for predicting the effects of changing environmental conditions for ecosystems. Collembola are abundant in terrestrial polar ecosystems and are integral to food-webs and soil nutrient cycling. Using available literature, we consider resistance (genetic diversity; behavioural avoidance and physiological tolerances; biotic interactions) and recovery potential for polar Collembola. Polar Collembola have high levels of genetic diversity, considerable capacity for behavioural avoidance, wide thermal tolerance ranges, physiological plasticity, generalist-opportunistic feeding habits and broad ecological niches. The biggest threats to the ongoing resistance of polar Collembola are increasing levels of dispersal (gene flow), increased mean and extreme temperatures, drought, changing biotic interactions, and the arrival and spread of invasive species. If resistance capacities are insufficient, numerous studies have highlighted that while some species can recover from disturbances quickly, complete community-level recovery is exceedingly slow. Species dwelling deeper in the soil profile may be less able to resist climate change and may not recover in ecologically realistic timescales given the current rate of climate change. Ultimately, diverse communities are more likely to have species or populations that are able to resist or recover from disturbances. While much of the Arctic has comparatively high levels of diversity and phenotypic plasticity; areas of Antarctica have extremely low levels of diversity and are potentially much more vulnerable to climate change.

The effect of soil pH and temperature on Folsomia candida transcriptional regulation

Differences in abiotic factors like temperature and soil pH can have a significant physiological impact on soil dwelling invertebrates and may confound results in ecotoxicological testing. In this study we exposed Folsomia candida to a range of two abiotic stress treatments (pH and temperature) for 3 days and measured gene expression of a panel of nine stress response genes with real-time Q-PCR. The exposure to different pH values had a minimal effect on the expression of the nine selected genes: only V-ATPase expression was significantly increased due to decreasing pH. ATPase expression was up-regulated, possibly due to increased proton trafficking across the cell membrane, at a lower pH. HSP70 was up-regulated in collembolans exposed to 30 degrees C, and along with HSP40 at 0 degrees C. We speculate that the minor pH effect on gene expression, compared to the temperature treatment, can be explained by the spatial restricted exposure to the external pH in the gut. Our data showed that only 1 or 2 stress response genes were transcriptionally affected by pH and temperature thus exerting minimal effects. The physiological effects of these treatments on F. candida might indicate interesting novel molecular mechanisms.

Evolutionary theory and studies of model organisms predict a cautiously positive perspective on the therapeutic use of hormesis for healthy aging in humans

Hormesis, the beneficial effects of mild stress exposures, is a well documented phenomenon in a range of organisms. The documentation mainly relies on relatively simple and controlled laboratory investigations. In order to better understand hormesis and predict the outcome of more complex and realistic conditions, a number of key issues should be investigated in much more detail. One obstacle is the development of precise treatments optimized for single individuals. Only then can we progress with the use of hormesis as a therapeutic tool for humans.