1,081 research outputs found

    A Global Database of Anomalies in Natural Populations, with an Illustration of Emerging Patterns Focussing on Countries of the Former Soviet Union

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    The literature on anomalies from natural populations of amphibians is enormous but widely dispersed and difficult to access. To fill the gap I compiled a global database that covers all extant and fossil amphibian species for which anomalies have been reported. The database focuses on externally visible anomalies. The database is an EXCEL file that provides data on: species, anomalies observed, class of anomalies, sample size, number of abnormal individuals, percentage of abnormal individuals, developmental stage, cause, year of observation, meadian year, country, location, remarks, and data sources. Using the territory of the former Soviet Union as example we illustrate the publication history, the percentage of urodelan and anuran species of the fauna for which anomalies have been reported, the number of cases reported for the different countries, and the frequency distribution of the number of abnormal individuals

    Anomalies in natural populations of amphibians overview, patterns and causes, methodological recommendation

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    The article represent analytic review on types and frequencies of amphibian anomalies in more than 2000 natural populations. The review has shown that there are neither standards in the way anomalies are assessed in the field, nor for the way they are scored or reported, which considerably hampers our ability to compare studies. To evaluate temporal trends, and to reveal underlying causes is a field and laboratory experiments that should be designed to test the effect(s) of hypothesized causes of abnormalities.Статья представляет аналитический обзор о типах и частотах аномалий амфибий в более чем 2 тыс. природных популяций. Обзор свидетельствует, что не существует стандартных способов оценки аномалий в естественных условиях, что значительно затрудняет наши возможности в проведении сравнительных исследований. Для оценки временных тенденций и выявления основных причин необходимы полевые и лабораторные эксперименты, которые должны быть разработаны для проверки гипотетических причин отклонений.I would like to thank Vladimir Vershinin (Ekaterinburg) for inviding me to the symposium and for help in accessing Russian publications. I would also like to thank the Ural State University for funding my participation

    Reversible Eu<sup>2+</sup> ↔ Eu<sup>3+</sup> transitions at Eu‐Si interfaces

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    Valence switching at Eu‐Si interfaces is demonstrated by resonant photoemission during repeated oxidation‐reduction cycles performed by room‐temperature O2 exposure and mild heating. The Eu2+ ↔ Eu3+ transitions are accompanied by Fermi level switching associated with changes in the stoichiometry of the surface heterostructure. The ability to cycle between two well‐defined magnetic states at a surface may be attractive in technological applications

    Patterns of richness across forest beetle communities—A methodological comparison of observed and estimated species numbers

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    Abstract Species richness is a frequently used measure of biodiversity. The compilation of a complete species list is an often unattainable goal. Estimators of species richness have been developed to overcome this problem. While the use of these estimators is becoming increasingly popular, working with the observed number of species is still common practice. To assess whether patterns of beetle communities based on observed numbers may be compared among each other, we compared patterns from observed and estimated numbers of species for beetle communities in the canopy of the Leipzig floodplain forest. These patterns were species richness and the number of shared species among three tree species and two canopy strata. We tested the applicability of the asymptotic Chao1 estimator and the estimate provided by the nonasymptotic rarefaction–extrapolation method for all tree species and both upper canopy and lower canopy. In the majority of cases, the ranking patterns of species richness for host tree species and strata were the same for the observed and estimated number of species. The ranking patterns of the number of species shared among host tree species and strata, however, were significantly different between observed and estimated values. Our results indicate that the observed number of species under‐represents species richness and the number of shared species. However, ranking comparisons of published patterns based on the number of observed species may be acceptable for species richness but likely not reliable for the number of shared species. Further studies are needed to corroborate this conclusion. We encourage to use estimators and to provide open access to data to allow comparative assessments

    Real-time detection of Fe·EDTA/H2O2-induced DNA cleavage by linear dichroism

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    The conditions for the measurement of linear dichroism (LD) can be adjusted so as to solely reflect the length and the flexibility of DNA. The real-time detection of the EDTA·Fe2+-induced oxidative cleavage of double-stranded native and synthetic DNAs was performed using LD. The decrease in the magnitude of the LD at 260 nm, which reflects an increase in the flexibility and a decrease in the length of the DNA, can be described by the sum of two or three exponential curves in relation to the EDTA·Fe2+ concentration. The fast component was assigned to the cleavage of one of the double strands, inducing an increase in the flexibility, while the other slower component was assigned to the cleavage of the double strand, resulting in the shortening of DNA. The decrease in the magnitude of the LD of poly[d(A-T)2] was similar to that of poly[d(I-C)2], while that of poly[d(G-C)2] was found to be the slowest, indicating that the resistance of poly[d(G-C)2] against the Fenton-type reagent was the strongest. This observation suggests that the amine group in the minor groove of the double helix may play an important role in slowing the EDTA·Fe2+-induced oxidative cleavage

    Hydrodynamic coupling between two fluid membranes

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    The coupled in-plane diffusion dynamics between point-particles embedded in stacked fluid membranes are investigated. We calculate the contributions to the coupling longitudinal and transverse diffusion coefficients due to particle motion within the different as well as the same membranes. The stacked geometry leads to a hydrodynamic coupling between the two membranes.Comment: 9 Pages, 5 figures. Accepted for publication in J. Phys.: Condens. Matte

    Biodiversity conservation across scales: lessons from a science–policy dialogue

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    One of the core challenges of biodiversity conservation is to better understand the interconnectedness and interactions of scales in ecological and governance processes. These interrelationships constitute not only a complex analytical challenge but they also open up a channel for deliberative discussions and knowledge exchange between and among various societal actors which may themselves be operating at various scales, such as policy makers, land use planners, members of NGOs, and researchers. In this paper, we discuss and integrate the perspectives of various disciplines academics and stakeholders who participated in a workshop on scales of European biodiversity governance organised in Brussels in the autumn of 2010. The 23 participants represented various governmental agencies and NGOs from the European, national, and sub-national levels. The data from the focus group discussions of the workshop were analysed using qualitative content analysis. The core scale-related challenges of biodiversity policy identified by the participants were cross-level and cross-sector limitations as well as ecological, social and social-ecological complexities that potentially lead to a variety of scale-related mismatches. As ways to address these cha- llenges the participants highlighted innovations, and an aim to develop new interdisciplinary approaches to support the processes aiming to solve current scale challenges

    Cytokine and immunoglobulin production by PWM-stimulated peripheral and tumor-infiltrating lymphocytes of undifferentiated nasopharyngeal carcinoma (NPC) patients

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    BACKGROUND: Undifferentiated Nasopharyngeal Carcinoma (NPC) patients show a characteristic pattern of antibody responses to the Epstein-Barr virus (EBV) which is regularly associated with this tumor. However, no EBV-specific cytotoxic activity is detectable by the standard chromium-release assay at both peripheral and intratumoral levels. The mechanisms underlying this discrepancy between the humoral and cellular immune responses in NPC are still unknown, but might be related to an imbalance in immunoregulatory interleukin production. In this report, we investigated the ability of peripheral (PBL) and tumor- infiltrating (TIL) lymphocytes of undifferentiated NPC patients to produce in vitro three interleukins (IL-2, IL-6, IL-10) and three immunoglobulin isotypes (IgM, IgG, IgA). METHODS: Lymphocytes from 17 patients and 17 controls were cultured in the presence of Pokeweed mitogen (PWM) for 12 days and their culture supernatants were tested for interleukins and immunoglobulins by specific enzyme-linked immunosorbent assays (ELISA). Data were analysed using Student's t-test and probability values below 5% were considered significant. RESULTS: The data obtained indicated that TIL of NPC patients produced significantly more IL-2 (p = 0,0002), IL-10 (p = 0,020), IgM (p= 0,0003) and IgG (p < 0,0001) than their PBL. On the other hand, patients PBL produced significantly higher levels of IL-2 (p = 0,022), IL-10 (p = 0,016) and IgM (p = 0,004) than those of controls. No significant differences for IL-6 and IgA were observed. CONCLUSION: Taken together, our data reinforce the possibility of an imbalance in immunoregulatory interleukin production in NPC patients. An increased ability to produce cytokines such as IL-10 may underlie the discrepancy between humoral and cellular immune responses characteristic of NPC
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