Variations of immune parameters in terrestrial isopods: a matter of gender, aging and Wolbachia

Ecological factors modulate animal immunocompetence and potentially shape the evolution of their immune systems. Not only environmental parameters impact on immunocompetence: Aging is one major cause of variability of immunocompetence between individuals, and sex-specific levels of immunocompetence have also been frequently described. Moreover, a growing core of data put in light that vertically transmitted symbionts can dramatically modulate the immunocompetence of their hosts. In this study, we addressed the influence of gender, age and the feminising endosymbiont Wolbachia (wVulC) on variations in haemocyte density, total PO activity and bacterial load in the haemolymph of the terrestrial isopod Armadillidium vulgare. This host–symbiont system is of particular interest to address this question since: (1) wVulC was previously shown as immunosuppressive in middle-aged females and (2) wVulC influences sex determination. We show that age, gender and Wolbachia modulate together immune parameters in A. vulgare. However, wVulC, which interacts with aging, appears to be the prominent factor interfering with both PO activity and haemocyte density. This interference with immune parameters is not the only aspect of wVulC virulence on its host, as reproduction and survival are also altered.     

Mutagenicity of diesel engine exhaust in the Ames / Salmonella assay using a direct exposure method

The aim of this study was to investigate the potential mutagenic activity of diesel engine exhaust in the Ames/Salmonella assay using a direct aerosol exposure system. So, TA 98 and TA 100 strains, with or without added S9 mix, were exposed to diesel emissions after varying degrees of filtration. Variants of these two strains, deficient in nitroreductase (TA 98NR and TA 100NR) or over-expressing O-Acetyl Transferase (YG 1024 and YG 1029), were also exposed to total (unfiltered) diesel exhaust to highlight the putative mutagenicity of any nitro-PAHs present in these emissions. Mutagenic activity of the diesel exhaust was demonstrated on Salmonella typhimurium, strains TA 100 and variants TA 100 NR and YG1029. The use of a particle filter did not modify the genotoxicity of the diesel emissions, indicating a major contribution of the gas phase to the mutagenicity of these diesel emissions. The prominent role of the particulate-associated nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) claimed by some authors working on diesel exhaust organic extracts was not confirmed by our results with native diesel exhaust exposure. Our results show that the gas phase is potentially more mutagenic than the particles alone.     

The interaction between reproductive cost and individual quality is mediated by oceanic conditions in a long-lived bird

Environmental variability, costs of reproduction, and heterogeneity in individual quality are three important sources of the temporal and interindividual variations in vital rates of wild populations. Based on an 18-year monitoring of an endangered, recently described, long-lived seabird, Monteiro's Storm-Petrel (Oceanodroma monteiroi), we designed multistate survival models to separate the effects of the reproductive cost (breeders vs. nonbreeders) and individual quality (successful vs. unsuccessful breeders) in relation to temporally variable demographic and oceanographic properties. The analysis revealed a gradient of individual quality from nonbreeders, to unsuccessful breeders, to successful breeders. The survival rates of unsuccessful breeders (0.90 +/- 0.023, mean +/- SE) tended to decrease in years of high average breeding success and were more sensitive to oceanographic variation than those of both (high-quality) successful breeders (0.97 +/- 0.015) and (low-quality) nonbreeders (0.83 +/- 0.028). Overall, our results indicate that reproductive costs act on individuals of intermediate quality and are mediated by environmental harshness.     

Assessing a Transition to 100% Renewable Power Generation in a Non-interconnected Area: A Case Study for La Réunion Island

Environmental Modeling & Assessment - In this paper, we present a comprehensive, multi-timescale approach to evaluate energy transition policies aiming at fully renewable generation in power...     

The politics and power effects of garbage recycling in Halifax,Canada

Abstract

The theoretical concept of ‘governmentality’, as developed by French political theorist Michel Foucault, presents three aspects: (a) an analysis of knowledge, (b) a study of the power effects of normalisation and resistance and (c) the possibility of a non‐essentialist ethic. Governmentality has not yet been applied to environmental issues. First, the concept of governmentality is explained briefly. Then, a detailed case study of the controversy surrounding a proposed municipal incinerator in metropolitan Halifax (Canada) provides an evaluation of the relevance and pertinence of the concept. The case study confirms: (1) the importance of discursive categories in the legitimisation process of local environmental policy; (2) the centrality of the tension between attempts by local authorities to normalise the conduct of the population and resistance presented by environmental groups and individuals; (3) the possibility for groups and individuals to articulate an alternative identity—a Green self—which goes beyond the existing boundaries.     

Multiple-criteria decision-aiding framework to analyze and assess the governance of sustainability

Past and present disasters and scandals, such as the BP Deepwater Horizon oil disaster in the Gulf of Mexico in 2010, the Servier Mediator (Benfluorex) scandal in 2009 and the Enron collapse in 2001, have uncovered weaknesses in governance issues. The authors argue that there is a need to develop methods and tools to diagnose and assess the governance of organizations with respect to Sustainable Development (SD). However, this task remains difficult due to the fact that it is difficult to appraise the quality of governance. The authors propose a protocol to diagnose and analyze the governance of SD and explore the use of multiple-criteria decision-aiding methods to achieve this task. Two aggregation methods to assess the global governance are proposed: (1) The identification of a final governance index for an Organization. This method helps in establishing a global diagnosis of the quality of the governance of an Organization with respect to SD challenges. The governance index is based on the calculation of three indexes: the partial opportunity index, the partial risk index and the partial equilibrium index. (2) The ranking of a set of Organizations according to their governance of SD. This method aims at assessing a set of Organizations based on a pairwise comparison according to a set of criteria that represents the seven domains of the ISO 26000 norm (ISO 26000—Guidance on social responsibility, 2010). This method is based on the outranking aggregation approach ELECTRE III. A practical example is used to illustrate two methods of governance assessment.     

Optimisation of a PMAxx™-RT-qPCR Assay and the Preceding Extraction Method to Selectively Detect Infectious Murine Norovirus Particles in Mussels

Human noroviruses are a major cause for gastroenteritis outbreaks. Filter-feeding bivalve molluscs, which accumulate noroviruses in their digestive tissues, are a typical vector for human infection. RT-qPCR, the established method for human norovirus detection in food, does not allow discrimination between infectious and non-infectious viruses and can overestimate potentially infectious viral loads. To develop a more accurate method of infectious norovirus load estimation, we combined intercalating agent propidium monoazide (PMAxx™)-pre-treatment with RT-qPCR assay using in vitro-cultivable murine norovirus. Three primer sets targeting different genome regions and diverse amplicon sizes were used to compare one-step amplification of a short genome fragment to three two-step long-range RT-qPCRs (7 kbp, 3.6 kbp and 2.3 kbp amplicons). Following initial assays performed on untreated infectious, heat-, or ultraviolet-inactivated murine noroviruses in PBS suspension, PMAxx™ RT-qPCRs were implemented to detect murine noroviruses subsequent to their extraction from mussel digestive tissues; virus extraction via anionic polymer-coated magnetic beads was compared with the proteinase K-dependent ISO norm. The long-range RT-qPCR process detecting fragments of more than 2.3 kbp allowed accurate estimation of the infectivity of UV-damaged murine noroviruses. While proteinase K extraction limited later estimation of PMAxx™ pre-treatment effects and was found to be unsuited to the assay, magnetic bead-captured murine noroviruses retained their infectivity. Genome copies of heat-inactivated murine noroviruses differed by 2.3 log₁₀ between RT-qPCR and PMAxx™-RT-qPCR analysis in bivalve molluscs, the PMAxx™ pre-treatment allowing a closer approximation of infectious titres. The combination of bead-based virus extraction and PMAxx™ RT-qPCR thus provides a more accurate model for the estimation of noroviral bivalve mollusc contamination than the conjunction of proteinase K extraction and RT-qPCR and has the potential (once validated utilising infectious human norovirus) to provide an added measure of security to food safety authorities in the hazard assessment of potential bivalve mollusc contamination.

     

The swimming crab Charybdis smithii: distribution, biology and trophic role in the pelagic ecosystem of the western Indian Ocean

Surface “swarms” of the swimming crabs Charybdis smithii are still considered as an unusual phenomenon in the open Indian Ocean, although their dense pelagic aggregations were already reported in waters off the Indian coast and in the northern Arabian Sea. Based on an extensive large-scale data series taken over 45 years, we demonstrate that C. smithii is common in the pelagic provinces of the western Indian Ocean driven by the wind monsoon regime. Swimming crabs are dispersed by the monsoon currents throughout the equatorial Indian Ocean. They aggregate at night in the upper 150-m layer, where their estimated biomass derived from pelagic trawling data can exceed 130 kg km⁻². Abundance of C. smithii can reach >15,000 ind. km⁻² in July (i.e. the peak of the south-west monsoon), declines by 50-fold in March and is negligible in May. C. smithii is an important prey for more than 30 species of abundant epipelagic top predators. In turn, it feeds on mesopelagic species. This swimming crab is a major species of the intermediate trophic levels and represents a crucial seasonal trophic link in the open ocean ecosystem of the western Indian Ocean. Outbursts in pelagic waters of huge biomasses of ordinarily benthic crustaceans (C. smithii and Natosquilla investigatoris) are a remarkable feature of the Indian Ocean, although similar, but smaller, events are reported in the Pacific and Atlantic Oceans.

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Local disturbance cycles and the maintenance of heterogeneity across scales in marine metapopulations

In marine systems, the occurrence and implications of disturbance-recovery cycles have been revealed at the landscape level, but only in demographically open or closed systems where landscape-level dynamics are assumed to have no feedback effect on regional dynamics. We present a mussel metapopulation model to elucidate the role of landscape-level disturbance cycles for regional response of mussel populations to onshore productivity and larval transport. Landscape dynamics are generated through spatially explicit rules, and each landscape is connected to its neighbor through unidirectional larval dispersal. The role of landscape disturbance cycles in the regional system behavior is elucidated (1) in demographically open vs. demographically coupled systems, in relation to (2) onshore reproductive output and (3) the temporal scale of landscape disturbance dynamics. By controlling for spatial structure at the landscape and metapopulation levels, we first demonstrate the interaction between landscape and oceanographic connectivity. The temporal scale of disturbance cycles, as controlled by mussel colonization rate, plays a critical role in the regional behavior of the system. Indeed, fast disturbance cycles are responsible for regional synchrony in relation to onshore reproductive output. Slow disturbance cycles, however, lead to increased robustness to changes in productivity and to demographic coupling. These testable predictions indicate that the occurrence and temporal scale of local disturbance-recovery dynamics can drive large-scale variability in demographically open systems, and the response of metapopulations to changes in nearshore productivity.