Examining the Osmotic Response of Acidihalobacter aeolianus after Exposure to Salt Stress

Acidihalobacter aeolianus is an acidophilic, halo-tolerant organism isolated from a marine environment near a hydrothermal vent, an ecosystem whereby levels of salinity and total dissolved salts are constantly fluctuating creating ongoing cellular stresses. In order to survive these continuing changes, the synthesis of compatible solutes—also known as organic osmolytes—is suspected to occur, aiding in minimising the overall impact of environmental instability. Previous studies on A. aeolianus identified genes necessary for the accumulation of proline, betaine and ectoine, which are known to act as compatible solutes in other halophilic species. In this study, the impact of increasing the osmotic stress as well as the toxic ion effect was investigated by subjecting A. aeolianus to concentrations of NaCl and MgSO4 up to 1.27 M. Exposure to high concentrations of Cl- resulted in the increase of ectC expression in log-phase cells with a corresponding accumulation of ectoine at stationary phase. Osmotic stress via MgSO4 exposure did not trigger the same up-regulation of ectC or accumulation of ectoine, indicating the transcriptionally regulated response against osmotic stress was induced by chloride toxicity. These findings have highlighted how the adaptive properties of halo-tolerant organisms in acidic environments are likely to differ and are dependent on the initial stressor.

Seasonality of Food Use and Caching in New Zealand Robins (Petroica Australis)

<p>Foraging behaviour in birds is strongly determined by temporal factors such as season and time of day. Most birds show a limited number of food use methods such as consuming, feeding to conspecifics, or discarding. A relatively small number of birds also cache food for later use. The expression of caching in birds has been attributed to numerous factors. However, noting the environmental instability experienced by most caching species, researchers tend to cite survival of future food scarcity as the predominant advantage. Recording the food use behaviour of wild birds is typically difficult and time consuming, and many studies of north-temperate food-caching birds are limited by long caching distances, protracted caching durations, and a lack of year-round data. Additionally, food-caching in Australasian passerines has received limited quantification. The naïveté of the New Zealand robin (Petroica australis) makes it ideal for behavioural observations in the wild. Robins express a wide range of food use behaviours within close proximity of observers, and cached food is retrieved within a few days. Food use can be observed year-round in a temperate environment that is relatively stable. Thus, food use decisions in robins can be assessed in a wider context. In this study, behavioural data were collected from robins inhabiting the Karori Wildlife Sanctuary in Wellington. Robin behaviour was quantified by presenting monogamous, paired birds an ephemeral food resource and observing their responses. Seasonal variation in food use differed with sex and season. Birds mediated their food use in response to the presence of conspecifics. Males dominated food use year-round. During the breeding season, males cached little, mostly feeding familial conspecifics. However, non-breeding males selfishly cached food. Conversely, female caching propensity was mediated by courtship feeding during the breeding season, and the threat of male pilferage outside of it. Birds did not appear to anticipate future food scarcity. Instead, food was cached in the season in which retrieval would be least necessary. In robins, food is opportunistically cached, mainly as a competitive response to excess food.</p>

Seasonality of Food Use and Caching in New Zealand Robins (Petroica Australis)

<p>Foraging behaviour in birds is strongly determined by temporal factors such as season and time of day. Most birds show a limited number of food use methods such as consuming, feeding to conspecifics, or discarding. A relatively small number of birds also cache food for later use. The expression of caching in birds has been attributed to numerous factors. However, noting the environmental instability experienced by most caching species, researchers tend to cite survival of future food scarcity as the predominant advantage. Recording the food use behaviour of wild birds is typically difficult and time consuming, and many studies of north-temperate food-caching birds are limited by long caching distances, protracted caching durations, and a lack of year-round data. Additionally, food-caching in Australasian passerines has received limited quantification. The naïveté of the New Zealand robin (Petroica australis) makes it ideal for behavioural observations in the wild. Robins express a wide range of food use behaviours within close proximity of observers, and cached food is retrieved within a few days. Food use can be observed year-round in a temperate environment that is relatively stable. Thus, food use decisions in robins can be assessed in a wider context. In this study, behavioural data were collected from robins inhabiting the Karori Wildlife Sanctuary in Wellington. Robin behaviour was quantified by presenting monogamous, paired birds an ephemeral food resource and observing their responses. Seasonal variation in food use differed with sex and season. Birds mediated their food use in response to the presence of conspecifics. Males dominated food use year-round. During the breeding season, males cached little, mostly feeding familial conspecifics. However, non-breeding males selfishly cached food. Conversely, female caching propensity was mediated by courtship feeding during the breeding season, and the threat of male pilferage outside of it. Birds did not appear to anticipate future food scarcity. Instead, food was cached in the season in which retrieval would be least necessary. In robins, food is opportunistically cached, mainly as a competitive response to excess food.</p>

The Natural History of Integrons

Integrons were first identified because of their central role in assembling and disseminating antibiotic resistance genes in commensal and pathogenic bacteria. However, these clinically relevant integrons represent only a small proportion of integron diversity. Integrons are now known to be ancient genetic elements that are hotspots for genomic diversity, helping to generate adaptive phenotypes. This perspective examines the diversity, functions, and activities of integrons within both natural and clinical environments. We show how the fundamental properties of integrons exquisitely pre-adapted them to respond to the selection pressures imposed by the human use of antimicrobial compounds. We then follow the extraordinary increase in abundance of one class of integrons (class 1) that has resulted from its acquisition by multiple mobile genetic elements, and subsequent colonisation of diverse bacterial species, and a wide range of animal hosts. Consequently, this class of integrons has become a significant pollutant in its own right, to the extent that it can now be detected in most ecosystems. As human activities continue to drive environmental instability, integrons will likely continue to play key roles in bacterial adaptation in both natural and clinical settings. Understanding the ecological and evolutionary dynamics of integrons can help us predict and shape these outcomes that have direct relevance to human and ecosystem health.

Capitalism and Sustainability: An Exploratory Content Analysis of Frameworks in Environmental Political Economy

A critical divide within environmental sociology concerns the relationship between capitalism and the environment. Risk society and ecological modernization scholars advance a concept of reflexive political economy, arguing that capitalism will transition from a dirty, industrial stage to a green, eco-friendly stage. In contrast, critical political economy scholars suggest that the core imperatives of capitalist accumulation are fundamentally unsustainable. We conduct a content analysis of 136 journal articles to assess how these frameworks have been implemented in empirical studies. Our analysis provides important commentary about the mechanisms, agents, magnitude, scale, temporality, and outcomes these frameworks analyze and employ, and the development of a hybrid perspective that borrows from both these perspectives. In addition, we reflect on how and why reflexive political economy has not answered key challenges leveled in the early 21st century, mainly the disconnect between greening values and the ongoing coupling of economic growth and environmental destruction. We also reflect on the significance of critical political economy, as the only framework we study that provides analysis of the roots of ecological crisis. Finally, we comment on the emergent hybrid perspective as a framework that attempts to reconcile new socioecological configurations in an era of increasing environmental instability.

Strong and ductile Fe-24Mn-3Cr alloy resistant against erosion-corrosion

The ternary-based Fe-24Mn-3Cr alloy has superior mechanical properties based on an attractive combination of high strength and ductility, with long-term environmental stability in highly corrosive environments compared to conventional ferritic steel alloys. This study reports that the environmental instability caused by the rapid electrochemical corrosion kinetics on the surface of conventional high Mn-bearing ferrous alloys could be overcome by a combination of high Mn–low Cr-balanced Fe and their synergistic interactions. In contrast to Cr-free Mn-bearing alloys, the high Mn–low Cr-bearing alloy showed comparatively lower corrosion kinetic parameters, without a continuously increasing trend, and higher polarization resistance according to electrochemical polarization and impedance spectroscopy measurements. Moreover, the rate of degradation caused by erosion–corrosion synergistic interaction under erosion–corrosion dynamic flow conditions was the lowest in the high Mn–low Cr-bearing alloy. These surface-inhibiting characteristics of the alloy were attributed primarily to the formation of a bilayer scale structure consisting of inner α-Fe2−xCrxO3/outer FexMn3−xO4 on the surface.

Temperate UV-Accelerated Weathering Cycle Combined with HT-GPC Analysis and Drop Point Testing for Determining the Environmental Instability of Polyethylene Films

Polyethylene films are one of the most frequently used packaging materials in our society, due to their combination of strength and flexibility. An unintended consequence of this high use has been the ever-increasing accumulation of polyethylene films in the natural environment. Previous attempts to understand their deterioration have either focused on their durability using polymer analysis; or they have focused on changes occurring during outdoor exposure. Herein, this study combines those strategies into one, by studying the chemical and physical changes in the polyethylene structure in a laboratory using molecular weight and IR spectroscopic mapping analysis, combined with temperate UV-accelerated weathering cycles. This approach has been correlated to real-world outdoor exposure timeframes by parallel testing of the sample polyethylene films in Florida and France. The formation of polyethylene microparticles or polyethylene waxes is elucidated through comparison of drop point testing and molecular weight analysis.

Evolutionary simulations clarify and reconcile biodiversity-disturbance models

There is significant geographic variation in species richness. However, the nature of the underlying relationships, such as that between species richness and environmental stability, remains unclear. The stability-time hypothesis suggests that environmental instability reduces species richness by suppressing speciation and increasing extinction risk. By contrast, the patch-mosaic hypothesis suggests that small-scale environmental instability can increase species richness by providing a steady supply of non-equilibrium environments. Although these hypotheses are often applied to different time scales, their core mechanisms are in conflict. Reconciling these apparently competing hypotheses is key to understanding how environmental conditions shape the distribution of biodiversity. Here, we use REvoSim, an individual-based, eco-evolutionary system, to model the evolution of sessile organisms in environments with varying magnitudes and scales of environmental instability. We demonstrate that when environments have substantial permanent heterogeneity, a high level of localized environmental instability reduces biodiversity, whereas in environments lacking permanent heterogeneity, high levels of localized instability increase biodiversity. By contrast, broad-scale environmental instability, acting on the same time scale, invariably reduces biodiversity. Our results provide a new view of the biodiversity–disturbance relationship that reconciles contrasting hypotheses within a single model and implies constraints on the environmental conditions under which those hypotheses apply. These constraints can inform attempts to conserve adaptive potential in different environments during the current biodiversity crisis.