Empirical maximum lifespan of earthworms is twice that of mice

We considered a Gompertzian model for the population dynamics of Eisenia andrei case-cohorts in artificial OECD soil under strictly controlled conditions. The earthworm culture was kept between 18 and 22°C at a constant pH of 5.0. In all, 77 lumbricids were carefully followed for almost 9 years, until the oldest died. The Eisenia median longevity is 4.25 years and the oldest specimen was 8.73 years. Eisenia cocoons were hand-sorted every 3 weeks, washed in distilled water, placed in Petri dishes, and counted. Regular removal did not reduce breeding. Each fertile cocoon contained on average two or three embryos. The failure rates (mortality and infertility percentages) are smooth power functions where the rate at time (n + 1) captured most of the phenomenology of the previous rate at time n, as expected by the considered law, but not at both the beginning and the end of this long-term laboratory study

Theory and Practice in Quantitative Genetics

With the rapid advances in molecular biology, the near completion of the human genome, the development of appropriate statistical genetic methods and the availability of the necessary computing power, the identification of quantitative trait loci has now become a realistic prospect for quantitative geneticists. We briefly describe the theoretical biometrical foundations underlying quantitative genetics. These theoretical underpinnings are translated into mathematical equations that allow the assessment of the contribution of observed (using DNA samples) and unobserved (using known genetic relationships) genetic variation to population variance in quantitative traits. Several statistical models for quantitative genetic analyses are described, such as models for the classical twin design, multivariate and longitudinal genetic analyses, extended twin analyses, and linkage and association analyses. For each, we show how the theoretical biometrical model can be translated into algebraic equations that may be used to generate scripts for statistical genetic software packages, such as Mx, Lisrel, SOLAR, or MERLIN. For using the former program a web-library (available from http://www.psy.vu.nl/mxbib) has been developed of freely available scripts that can be used to conduct all genetic analyses described in this paper

Prospective mixture risk assessment and management prioritizations for river catchments with diverse land uses

Ecological risk assessment increasingly focuses on risks from chemical mixtures and multiple stressors because ecosystems are commonly exposed to a plethora of contaminants and nonchemical stressors. To simplify the task of assessing potential mixture effects, we explored 3 land use–related chemical emission scenarios. We applied a tiered methodology to judge the implications of the emissions of chemicals from agricultural practices, domestic discharges, and urban runoff in a quantitative model. The results showed land use–dependent mixture exposures, clearly discriminating downstream effects of land uses, with unique chemical “signatures” regarding composition, concentration, and temporal patterns. Associated risks were characterized in relation to the land-use scenarios. Comparisons to measured environmental concentrations and predicted impacts showed relatively good similarity. The results suggest that the land uses imply exceedances of regulatory protective environmental quality standards, varying over time in relation to rain events and associated flow and dilution variation. Higher-tier analyses using ecotoxicological effect criteria confirmed that species assemblages may be affected by exposures exceeding no-effect levels and that mixture exposure could be associated with predicted species loss under certain situations. The model outcomes can inform various types of prioritization to support risk management, including a ranking across land uses as a whole, a ranking on characteristics of exposure times and frequencies, and various rankings of the relative role of individual chemicals. Though all results are based on in silico assessments, the prospective land use–based approach applied in the present study yields useful insights for simplifying and assessing potential ecological risks of chemical mixtures and can therefore be useful for catchment-management decisions

Waterkwaliteit zonder toxiciteit

Schoon oppervlaktewater zonder microverontreinigingen – wie wil dat niet? Maar we gebruiken meer dan 100.000 chemische stoffen! Maatregelen zijn nodig, maar welke? Hoe ver kom je door individuele stoffen te onderzoeken? En hoe kijk je naar realistische mengsels? Sinds kort is er de Ecologische Sleutelfactor Toxiciteit (ESF-Toxiciteit). Hiermee wordt het mogelijk om te werken aan de verbetering van de waterkwaliteit door heel precies de stoffen en de plekken met de grootste risico’s te identificeren

Waterkwaliteit zonder toxiciteit

Schoon oppervlaktewater zonder microverontreinigingen – wie wil dat niet? Maar we gebruiken meer dan 100.000 chemische stoffen! Maatregelen zijn nodig, maar welke? Wat heb je aan kennis over individuele stoffen? En hoe onderzoek je mengsels? Met de Ecologische Sleutelfactor Toxiciteit (ESF-Toxiciteit) wordt het mogelijk om heel precies de stoffen en de plekken met de grootste risico’s te identificeren

Green Swans countering chemical pollution.

If a problem has exponential features, its solution asks for counter-exponential approaches. Chemical pollution appears to be such a problem. Analyses of chemical hazards to human health, biodiversity, and ecosystem services and estimates of the cost of inaction suggest the potential for adverse impacts, and analyses of trends in the chemical economy appear exponential in kind. Here, we argue that we need and can develop an exponential and application-focused mindset in thinking about solutions

Methods of synthesizing qualitative research studies for health technology assessment

OBJECTIVES Synthesizing qualitative research is an important means of ensuring the needs, preferences, and experiences of patients are taken into account by service providers and policy makers, but the range of methods available can appear confusing. This study presents the methods for synthesizing qualitative research most used in health research to-date and, specifically those with a potential role in health technology assessment. METHODS To identify reviews conducted using the eight main methods for synthesizing qualitative studies, nine electronic databases were searched using key terms including meta-ethnography and synthesis. A summary table groups the identified reviews by their use of the eight methods, highlighting the methods used most generally and specifically in relation to health technology assessment topics. RESULTS Although there is debate about how best to identify and quality appraise qualitative research for synthesis, 107 reviews were identified using one of the eight main methods. Four methods (meta-ethnography, meta-study, meta-summary, and thematic synthesis) have been most widely used and have a role within health technology assessment. Meta-ethnography is the leading method for synthesizing qualitative health research. Thematic synthesis is also useful for integrating qualitative and quantitative findings. Four other methods (critical interpretive synthesis, grounded theory synthesis, meta-interpretation, and cross-case analysis) have been under-used in health research and their potential in health technology assessments is currently under-developed. CONCLUSIONS Synthesizing individual qualitative studies has becoming increasingly common in recent years. Although this is still an emerging research discipline such an approach is one means of promoting the patient-centeredness of health technology assessments

The challenges of applying planetary boundaries as a basis for strategic decision-making in companies with global supply chains

YesThe Planetary Boundaries (PB) framework represents a significant advance in specifying the ecological constraints on human development. However, to enable decision-makers in business and public policy to respect these constraints in strategic planning, the PB framework needs to be developed to generate practical tools. With this objective in mind, we analyse the recent literature and highlight three major scientific and technical challenges in operationalizing the PB approach in decision-making: first, identification of thresholds or boundaries with associated metrics for different geographical scales; second, the need to frame approaches to allocate fair shares in the 'safe operating space' bounded by the PBs across the value chain and; third, the need for international bodies to co-ordinate the implementation of the measures needed to respect the Planetary Boundaries. For the first two of these challenges, we consider how they might be addressed for four PBs: climate change, freshwater use, biosphere integrity and chemical pollution and other novel entities. Four key opportunities are identified: (1) development of a common system of metrics that can be applied consistently at and across different scales; (2) setting 'distance from boundary' measures that can be applied at different scales; (3) development of global, preferably open-source, databases and models; and (4) advancing understanding of the interactions between the different PBs. Addressing the scientific and technical challenges in operationalizing the planetary boundaries needs be complemented with progress in addressing the equity and ethical issues in allocating the safe operating space between companies and sectors

Understanding the Adaptive Growth Strategy of Lactobacillus plantarum by In Silico Optimisation

In the study of metabolic networks, optimization techniques are often used to predict flux distributions, and hence, metabolic phenotype. Flux balance analysis in particular has been successful in predicting metabolic phenotypes. However, an inherent limitation of a stoichiometric approach such as flux balance analysis is that it can predict only flux distributions that result in maximal yields. Hence, previous attempts to use FBA to predict metabolic fluxes in Lactobacillus plantarum failed, as this lactic acid bacterium produces lactate, even under glucose-limited chemostat conditions, where FBA predicted mixed acid fermentation as an alternative pathway leading to a higher yield. In this study we tested, however, whether long-term adaptation on an unusual and poor carbon source (for this bacterium) would select for mutants with optimal biomass yields. We have therefore adapted Lactobacillus plantarum to grow well on glycerol as its main growth substrate. After prolonged serial dilutions, the growth yield and corresponding fluxes were compared to in silico predictions. Surprisingly, the organism still produced mainly lactate, which was corroborated by FBA to indeed be optimal. To understand these results, constraint-based elementary flux mode analysis was developed that predicted 3 out of 2669 possible flux modes to be optimal under the experimental conditions. These optimal pathways corresponded very closely to the experimentally observed fluxes and explained lactate formation as the result of competition for oxygen by the other flux modes. Hence, these results provide thorough understanding of adaptive evolution, allowing in silico predictions of the resulting flux states, provided that the selective growth conditions favor yield optimization as the winning strategy