Dioxin alters inflammatory responses to lipopolysaccharide

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has well characterized effects on specific immune responses, but the effects on the innate immune system are less understood. The effect of TCDD on inflammatory responses induced by lipopolysaccharide (LPS) was evaluated in C57BL/6J female mice. Mice were treated with 30?µg?kg^?1 TCDD or vehicle once, p.o., and 4 days later, animals received LPS (0.05?×?10⁷?EU?kg^?1, i.p.) or vehicle. Inflammatory mediators and the liver injury marker, alanine aminotransferase (ALT), were measured, and liver histology was evaluated. TCDD-treated animals had higher plasma ALT activity than vehicle-treated animals, but the effect was mild and time-dependent. Few changes in liver histopathology were observed, mainly represented in greater steatosis in TCDD/LPS-treated mice compared to mice treated with LPS or TCDD alone. LPS produced a time-dependent increase in the plasma concentrations of interleukins (IL)-6, -10, and -12 and interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein (MCP)-1. With the exception of IL-12, concentrations of each of these mediators were higher in plasma of mice co-treated with TCDD and LPS compared to either agent alone. The dose–response curve for the concentration of IL-6 in plasma suggested that dioxin increased the potency of LPS to cause the release of this cytokine but not the maximal response. Co-treatment with TCDD and LPS also led to greater expression of mRNA for IL-10 and IFN-γ compared to either TCDD or LPS alone. These results suggest that TCDD changes the inflammatory cytokine profile induced by LPS and that LPS enhances the hepatic steatotic response to TCDD.     

Responses of the earthworm Eisenia andrei exposed to sublethal aluminium levels in an artificial soil substrate

Industrial discharges of Al are increasingly common. In this study, the activities of three antioxidases, malondialdehyde (MDA) content and changes in coelomocytes were investigated in earthworms (Eisenia andrei) exposed to different concentrations of aluminium chloride (range 0–200 mg Al kg^?1 dry soil) in artificial soils for 32 days. Within the first 16 days of Al exposure, catalase activity was elevated in most treatments, while the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were inhibited in all treatments. After 16 days exposure, SOD and GSH-Px activities returned to normal at lower Al concentrations, but were still inhibited at higher concentrations, hence the inhibition of SOD and GSH-Px showed some exposure-level dependence during the late exposure phase. MDA content was significantly elevated from 16 days after initial exposure. Neutral Red retention time of coelomocytes decreased at the highest exposure concentrations after 32 days, and an increased proportion of cells showing membrane damage was also observed at this time using flow cytometry. We conclude that excessive Al in soils can cause oxidative stress and cell damage in earthworms. Hence, Al accumulation in the environment may present an ecological hazard through suppression of the important functions of earthworms in soil ecosystems.     

Pathogen-associated self-medication behavior in the honeybee Apis mellifera

Honeybees, Apis mellifera, have several prophylactic disease defense strategies, including the foraging of antibiotic, antifungal, and antiviral compounds of plant products. Hence, honey and pollen contain many compounds that prevent fungal and bacterial growth and inhibit viral replication. Since these compounds are also fed to the larvae by nurse bees, they play a central role for colony health inside the hive. Here, we show that honeybee nurse bees, infected with the microsporidian gut parasite Nosema ceranae, show different preferences for various types of honeys in a simultaneous choice test. Infected workers preferred honeys with a higher antibiotic activity that reduced the microsporidian infection after the consumption of the honey. Since nurse bees feed not only the larvae but also other colony members, this behavior might be a highly adaptive form of therapeutic medication at both the individual and the colony level.     

Brood temperature, task division and colony survival in honeybees: A model

One of the mechanisms by which honeybees regulate division of labour among their colony members is age polyethism. Here the younger bees perform in-hive tasks such as heating and the older ones carry out tasks outside the hive such as foraging. Recently it has been shown that the higher developmental temperatures of the brood, which occur in the centre of the brood nest, reduce the age at which individuals start to forage once they are adult. It is unknown whether this effect has an impact on the survival of the colony. The aim of this paper is to study the consequences of the temperature gradient on the colony survival in a model on the basis of empirical data.We created a deterministic simulation of a honeybee colony (Apis mellifera) which we tuned to our empirical data. In the model in-hive bees regulate the temperature of the brood nest by their heating activities. These temperatures determine the age of first foraging in the newly emerging bees and thus the number of in-hive bees present in the colony. The results of the model show that variation in the onset of foraging due to the different developmental temperatures has little impact on the population dynamics and on the absolute number of bees heating the nest unless we increase this effect by several times to unrealistic values, where individuals start foraging up to 10 days earlier or later. Rather than on variation in the onset of foraging due to the temperature gradient it appears that the survival of the colony depends on a minimal number of bees available for heating at the beginning of the simulation.     

Power evaluation of focused cluster tests

Many statistical tests have been developed to assess the significance of clusters of disease located around known sources of environmental contaminants, also known as focused disease clusters. The majority of focused-cluster tests were designed to detect a particular spatial pattern of clustering, one in which the disease cluster centers around the pollution source and declines in a radial fashion with distance. However, other spatial patterns of environmentally related disease clusters are likely given that the spatial dispersion patterns of environmental contaminants, and thus human exposure, depend on a number of factors (i.e., meteorology and topography). For this study, data were simulated with five different spatial patterns of disease clusters, reflecting potential pollutant dispersion scenarios: (1) a radial effect decreasing with increasing distance, (2) a radial effect with a defined peak and decreasing with distance, (3) a simple angular effect, (4) an angular effect decreasing with increasing distance and (5) an angular effect with a defined peak and decreasing with distance. The power to detect each type of spatially distributed disease cluster was evaluated using Stone’s Maximum Likelihood Ratio Test, Tango’s Focused Test, Bithell’s Linear Risk Score Test, and variations of the Lawson–Waller Score Test. Study findings underscore the importance of considering environmental contaminant dispersion patterns, particularly directional effects, with respect to focused-cluster test selection in cluster investigations. The effect of extra variation in risk also is considered, although its effect is not substantial in terms of the power of tests.     

Achieving a real-time online monitoring system for conservation culturomics

Environmental monitoring is increasingly shifting toward a set of systems that describe changes in real time. In ecology specifically, a series of challenges have prevented the rollout of real-time monitoring for features such as biodiversity change or ecosystem service provision. Conservation culturomics, a field concerned with interactions between people and nature, is well placed to demonstrate how monitoring might move toward a network of real-time platforms, given its existence exclusively in the digital realm. We examined a set of considerations associated with the development of real-time monitoring platforms for conservation culturomics and introduce a near real-time platform for the Species Awareness Index, a global index of changing biodiversity awareness derived from the rate of change in page views for species on Wikipedia. This platform will update automatically each month, operating in near real time ( https://joemillard.shinyapps.io/Real_time_SAI/ ). There are plans to make the underlying data queryable via an application programing interface independent of the platform. The real-time Species Awareness Index will represent the first real-time and entirely automated conservation culturomic platform and one of the first real-time platforms in the discipline of ecology. Real-time monitoring for culturomics can provide insight into human–nature interactions as they play out in the physical realm and provide a framework for the development of real-time monitoring in ecology. Real-time monitoring metrics can be processed on private virtual machines and hosted on publicly available cloud services. Conservation now needs an online, real-time observatory that can evolve with the structure of the web.     

Documenting lemming population change in the Arctic: Can we detect trends?

Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still active. The sites were not evenly distributed with notably Russia and high Arctic Canada underrepresented. Abundance was monitored at all sites, but methods and levels of precision varied greatly. Other important attributes such as health, genetic diversity and potential drivers of population change, were often not monitored. There was no evidence that lemming populations were decreasing in general, although a negative trend was detected for low arctic populations sympatric with voles. To keep the pace of arctic change, we recommend maintaining long-term programmes while harmonizing methods, improving spatial coverage and integrating an ecosystem perspective.     

Fish Migration, Dams, and Loss of Ecosystem Services in the Mekong Basin

The past decade has seen increased international recognition of the importance of the services provided by natural ecosystems. It is unclear however whether such international awareness will lead to improved environmental management in many regions. We explore this issue by examining the specific case of fish migration and dams on the Mekong river. We determine that dams on the Mekong mainstem and major tributaries will have a major impact on the basin’s fisheries and the people who depend upon them for food and income. We find no evidence that current moves towards dam construction will stop, and consider two scenarios for the future of the fisheries and other ecosystems of the basin. We conclude that major investment is required in innovative technology to reduce the loss of ecosystem services, and alternative livelihood strategies to cope with the losses that do occur.     

Effects of Heating Season on Residential Indoor and Outdoor Polycyclic Aromatic Hydrocarbons, Black Carbon, and Particulate Matter in an Urban Birth Cohort

Exposure to air pollutants has been associated with adverse health effects. However, analyses of the effects of season and ambient parameters such as ozone have not been fully conducted. Residential indoor and outdoor air levels of polycyclic aromatic hydrocarbons (PAH), black carbon (measured as absorption coefficient [Abs]), and fine particulate matter <2.5 μm (PM)(2.5) were measured over two-weeks in a cohort of 5-6 year old children (n=334) living in New York City's Northern Manhattan and the Bronx between October 2005 and April 2010. The objectives were to: 1) characterize seasonal changes in indoor and outdoor levels and indoor/outdoor (I/O) ratios of PAH (gas + particulate phase; dichotomized into Σ(8)PAH(semivolatile) (MW 178-206), and Σ(8)PAH(nonvolatile) (MW 228-278)), Abs, and PM(2.5); and 2) assess the relationship between PAH and ozone. Results showed that heating compared to nonheating season was associated with greater Σ(8)PAH(nonvolatile) (p<0.001) and Abs (p<0.05), and lower levels of Σ(8)PAH(semivolatile) (p<0.001). In addition, the heating season was associated with lower I/O ratios of Σ(8)PAH(nonvolatile) and higher I/O ratios of Σ(8)PAH(semivolatile) (p<0.001) compared to the nonheating season. In outdoor air, Σ(8)PAH(nonvolatile) was correlated negatively with community-wide ozone concentration (p<0.001). Seasonal changes in emission sources, air exchanges, meteorological conditions and photochemical/chemical degradation reactions are discussed in relationship to the observed seasonal trends.     

Natural resource dependence and the accumulation of physical and human capital in Latin America

In a simultaneous model of human and physical capital accumulation for 17 Latin American countries from 1975 to 2004, we show that overall resource dependence has no significant direct effect on physical and human capital. When disaggregating the natural resource variable into sub-categories, we find that petroleum export dependence has a significant positive direct effect on physical capital, but a significant negative direct effect on human capital. Agricultural export dependence shows a significant negative direct effect on physical capital. Petroleum exports have a long run positive effect on physical capital but a negative long run effect on human capital. Agricultural exports have a negative long run effect on physical and human capital.