The critical importance of defined media conditions in Daphnia magna nanotoxicity studies

AbstractDue to the widespread use of silver nanoparticles (AgNPs), the likelihood of them entering the environment has increased and they are known to be potentially toxic. Currently, there is little information on the dynamic changes of AgNPs in ecotoxicity exposure media and how this may affect toxicity. Here, the colloidal stability of three different sizes of citrate-stabilized AgNPs was assessed in standard strength OECD ISO exposure media, and in 2-fold (media2) and 10-fold (media10) dilutions by transmission electron microscopy (TEM) and atomic force microscopy (AFM) and these characteristics were related to their toxicity towards Daphnia magna. Aggregation in undiluted media (media1) was rapid, and after diluting the medium by a factor of 2 or 10, aggregation was reduced, with minimal aggregation over 24h occurring in media10. Acute toxicity measurements were performed using 7nm diameter particles in media1 and media10. In media10 the EC50 of the 7nm particles for D. magna neonates was calculated to be 7.46μgL−1 with upper and lower 95% confidence intervals of 6.84μgL−1 and 8.13μgL−1 respectively. For media1, an EC50 could not be calculated, the lowest observed adverse effect concentration (LOAEC) of 11.25μgL−1 indicating a significant reduction in toxicity compared to that in media10. The data suggest the increased dispersion of nanoparticles leads to enhanced toxicity, emphasising the importance of appropriate media composition to fully assess nanoparticle toxicity in aquatic ecotoxicity tests

Environmental release, fate and ecotoxicological effects of manufactured ceria nanomaterials

Recent interest in the environmental fate and effects of manufactured CeO2 nanomaterials (nanoceria) has stemmed from its expanded use for a variety of applications including fuel additives, catalytic converters, chemical and mechanical planarization media and other uses. This has led to a wave of publications on the toxicological effects of nanoceria in ecological receptor species, but only limited information is available on possible environmental releases, concentrations in environmental media, or environmental transformations. In this paper, we make initial estimates of likely environmental releases and exposure concentrations in soils and water and compare them to published toxicity values. Insufficient information was available to estimate aquatic exposures, but we estimated inputs to a hypothetical wastewater treatment plant that could result in effluent concentrations that would result in acute toxicity to the most sensitive aquatic organisms tested so far, cyanobacteria. The purpose of this exercise is to identify which areas are lacking in data to perform either regional or site specific ecological risk assessments. While estimates can be made for releases from use as a diesel fuel additive, and predicted toxicity is low in most terrestrial species tested to date, estimates for releases from other uses are difficult at this stage. We recommend that future studies focus on environmentally realistic exposures that take into account potential environmental transformations of the nanoceria surface as well as chronic toxicity studies in benthic aquatic organisms, soil invertebrates and microorgansims

IFITM3 restricts the morbidity and mortality associated with influenza

The 2009 H1N1 influenza pandemic showed the speed with which a novel respiratory virus can spread and the ability of a generally mild infection to induce severe morbidity and mortality in a subset of the population. Recent in vitro studies show that the interferon-inducible transmembrane (IFITM) protein family members potently restrict the replication of multiple pathogenic viruses1, 2, 3, 4, 5, 6, 7. Both the magnitude and breadth of the IFITM proteins’ in vitro effects suggest that they are critical for intrinsic resistance to such viruses, including influenza viruses. Using a knockout mouse model8, we now test this hypothesis directly and find that IFITM3 is essential for defending the host against influenza A virus in vivo. Mice lacking Ifitm3 display fulminant viral pneumonia when challenged with a normally low-pathogenicity influenza virus, mirroring the destruction inflicted by the highly pathogenic 1918 ‘Spanish’ influenza9, 10. Similar increased viral replication is seen in vitro, with protection rescued by the re-introduction of Ifitm3. To test the role of IFITM3 in human influenza virus infection, we assessed the IFITM3 alleles of individuals hospitalized with seasonal or pandemic influenza H1N1/09 viruses. We find that a statistically significant number of hospitalized subjects show enrichment for a minor IFITM3 allele (SNP rs12252-C) that alters a splice acceptor site, and functional assays show the minor CC genotype IFITM3 has reduced influenza virus restriction in vitro. Together these data reveal that the action of a single intrinsic immune effector, IFITM3, profoundly alters the course of influenza virus infection in mouse and human

Preferences for different flagship types in fundraising for nature conservation

Environmental non-governmental organizations (ENGOs) appeal to private donors for conservation fundraising, often employing single species flagships as their fundraising strategy. Previous studies suggest that donor preferences vary, and can be divided into segments. Just as preferences towards species can vary, preferences towards different flagship types may also differ. Thus, opportunities may exist to enhance the use of other flagship types such as flagship fleets, ecosystems or biodiversity in fundraising. Although previous studies have found that aesthetic appeal, locality or threat status can explain the decision to donate, it is unclear how these attributes influence choices between flagship types. We conducted a discrete choice experiment on donor preferences towards different flagship types in the United Kingdom (n = 380) and the United States (n = 374), and explored how flagship attributes and socio-demographic variables affect potential donors' choices. Latent class modeling revealed seven donor segments in both countries that varied in their preferences of flagship types and attributes, as well as in their price-sensitivity. Some segments were similar for both countries, but the US segments were more polarized regarding price-sensitivity. Most respondents favored biodiversity targets in their choices, and ecosystems were more popular than species-based flagships. To enhance their fundraising capacity, ENGOs should extend their donation targets beyond flagship species, and develop more targeted marketing strategies for different audiences. Our research also demonstrates the need for further research to examine respondents' characteristics, such as personal values or environmental concern, which would allow more precisely targeted marketing to specific donor segments, e.g. through social media channels.Peer reviewe

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What are critical features of science curriculum materials that impact student and teacher outcomes?

Large investments are made in curriculum materials with the goal of supporting science education reform. However, relatively little evidence is available about what features of curriculum materials really matter to impact student and teacher learning. To address this need, the current study examined curriculum features associated with student and teacher outcomes. We reviewed sample curriculum materials and documentation reporting on the instructional outcomes of 51 research-based K–12 science curriculum materials. Our findings reveal that teacher supports, rather than student supports, had positive impacts on both student and teacher outcomes. Specifically, positive student outcomes were associated with curriculum materials with a larger scope and with materials that provide teachers with information about students’ ideas and recommended instructional strategies. Positive teacher outcomes were associated with the presence of information about targeted standards and recommended instructional strategies. Relatively fewer studies reported on teacher outcomes, and evidence about other dimensions of curriculum materials impact (e.g., spread, sustainability) was difficult to find. Overall, these results reveal the broad importance of embedding teacher supports and ensuring sufficient scope of content across coordinated curriculum units to support the development of conceptual understanding over time. Implications for the design of new curriculum materials and further research are discussed