1,466 research outputs found

    Selection and phylogenetics of salmonid MHC class I: wild brown trout (Salmo trutta) differ from a non-native introduced strain

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    We tested how variation at a gene of adaptive importance, MHC class I (UBA), in a wild, endemic Salmo trutta population compared to that in both a previously studied non-native S. trutta population and a co-habiting Salmo salar population ( a sister species). High allelic diversity is observed and allelic divergence is much higher than that noted previously for cohabiting S. salar. Recombination was found to be important to population-level divergence. The alpha 1 and alpha 2 domains of UBA demonstrate ancient lineages but novel lineages are also identified at both domains in this work. We also find examples of recombination between UBA and the non-classical locus, ULA. Evidence for strong diversifying selection was found at a discrete suite of S. trutta UBA amino acid sites. The pattern was found to contrast with that found in re-analysed UBA data from an artificially stocked S. trutta population

    Pilot-aided estimation and equalisation of a Radio-over-Fibre system in Wideband Code Division Multiple Access

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    In this study, the impact of a Radio-over-Fibre (RoF) subsystem on the capacity performance of wideband code division multiple access is evaluated. This study investigates the use of pilot-aided channel estimation to compensate for the optical subsystem non-linearities for different channel conditions, estimation intervals and coding schemes. The results show that pilot-aided channel estimation is an effective method for compensating the composite impairments of the optical subsystem and the radio frequency (RF) channel. It is found that there is always a suitable pilot power level which maximises the system capacity performance regardless of coding scheme and channel condition. Also, the peak capacity is only slightly affected by a decrease in the estimation interval

    Plural valuation of nature for equity and sustainability: Insights from the Global South

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    Plural valuation is about eliciting the diverse values of nature articulated by different stakeholders in order to inform decision making and thus achieve more equitable and sustainable outcomes. We explore what approaches align with plural valuation on the ground, as well as how different social-ecological contexts play a role in translating plural valuation into decisions and outcomes. Based on a co-constructed analytical approach relying on empirical information from ten cases from the Global South, we find that plural valuation contributes to equitable and sustainable outcomes if the valuation process: 1) is based on participatory value elicitation approaches; 2) is framed with a clear action-oriented purpose; 3) provides space for marginalized stakeholders to articulate their values in ways that can be included in decisions; 4) is used as a tool to identify and help reconcile different cognitive models about human-nature relations; and 5) fosters open communication and collaboration among stakeholders. We also find that power asymmetries can hinder plural valuation. As interest and support for undertaking plural valuation grows, a deeper understanding is needed regarding how it can be adapted to different purposes, approaches, and social-ecological contexts in order to contribute to social equity and sustainability

    Pre-M Phase-promoting Factor Associates with Annulate Lamellae in Xenopus Oocytes and Egg Extracts

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    We have used complementary biochemical and in vivo approaches to study the compartmentalization of M phase-promoting factor (MPF) in prophase Xenopus eggs and oocytes. We first examined the distribution of MPF (Cdc2/CyclinB2) and membranous organelles in high-speed extracts of Xenopus eggs made during mitotic prophase. These extracts were found to lack mitochondria, Golgi membranes, and most endoplasmic reticulum (ER) but to contain the bulk of the pre-MPF pool. This pre-MPF could be pelleted by further centrifugation along with components necessary to activate it. On activation, Cdc2/CyclinB2 moved into the soluble fraction. Electron microscopy and Western blot analysis showed that the pre-MPF pellet contained a specific ER subdomain comprising "annulate lamellae" (AL): stacked ER membranes highly enriched in nuclear pores. Colocalization of pre-MPF with AL was demonstrated by anti-CyclinB2 immunofluorescence in prophase oocytes, in which AL are positioned close to the vegetal surface. Green fluorescent protein-CyclinB2 expressed in oocytes also localized at AL. These data suggest that inactive MPF associates with nuclear envelope components just before activation. This association may explain why nuclei and centrosomes stimulate MPF activation and provide a mechanism for targeting of MPF to some of its key substrates

    Exploring the usefulness of scenario archetypes in science-policy processes: experience across IPBES assessments

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    Scenario analyses have been used in multiple science-policy assessments to better understand complex plausible futures. Scenario archetype approaches are based on the fact that many future scenarios have similar underlying storylines, assumptions, and trends in drivers of change, which allows for grouping of scenarios into typologies, or archetypes, facilitating comparisons between a large range of studies. The use of scenario archetypes in environmental assessments foregrounds important policy questions and can be used to codesign interventions tackling future sustainability issues. Recently, scenario archetypes were used in four regional assessments and one ongoing global assessment within the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services (IPBES). The aim of these assessments was to provide decision makers with policy-relevant knowledge about the state of biodiversity, ecosystems, and the contributions they provide to people. This paper reflects on the usefulness of the scenario archetype approach within science-policy processes, drawing on the experience from the IPBES assessments. Using a thematic analysis of (a) survey data collected from experts involved in the archetype analyses across IPBES assessments, (b) notes from IPBES workshops, and (c) regional assessment chapter texts, we synthesize the benefits, challenges, and frontiers of applying the scenario archetype approach in a science-policy process. Scenario archetypes were perceived to allow syntheses of large amounts of information for scientific, practice-, and policy-related purposes, streamline key messages from multiple scenario studies, and facilitate communication of them to end users. In terms of challenges, they were perceived as subjective in their interpretation, oversimplifying information, having a limited applicability across scales, and concealing contextual information and novel narratives. Finally, our results highlight what methodologies, applications, and frontiers in archetype-based research should be explored in the future. These advances can assist the design of future large-scale sustainability-related assessment processes, aiming to better support decisions and interventions for equitable and sustainable futures

    Mosaicism for combined tetrasomy of chromosomes 8 and 18 in a dysmorphic child: A result of failed tetraploidy correction?

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    <p>Abstract</p> <p>Background</p> <p>Mosaic whole-chromosome tetrasomy has not previously been described as a cause of fetal malformations.</p> <p>Case presentation</p> <p>In a markedly dysmorphic child with heart malformations and developmental delay, CGH analysis of newborn blood DNA suggested a 50% dose increase of chromosomes 8 and 18, despite a normal standard karyotype investigation. Subsequent FISH analysis revealed leukocytes with four chromosomes 8 and four chromosomes 18. The child's phenotype had resemblance to both mosaic trisomy 8 and mosaic trisomy 18. The double tetrasomy was caused by mitotic malsegregation of all four chromatids of both chromosome pairs. A possible origin of such an error is incomplete correction of a tetraploid state resulting from failed cytokinesis or mitotic slippage during early embryonic development.</p> <p>Conclusion</p> <p>This unique case suggests that embryonic cells may have a mechanism for tetraploidy correction that involves mitotic pairing of homologous chromosomes.</p

    Construction of a Microscopic Model for Yb and Tm Compounds on the Basis of a \mib{j}-\mib{j} Coupling Scheme

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    We provide a prescription to construct a microscopic model for heavy lanthanide systems such as Yb and Tm compounds by exploiting a jj-jj coupling scheme. Here we consider a situation with a large spin-orbit coupling, in which jj=5/2 sextet is fully occupied, while jj=7/2 octet is partially occupied, where jj denotes total angular momentum. We evaluate crystalline electric field potentials and Coulomb interactions among the states of the jj=7/2 octet to construct a local Hamiltonian in the jj-jj coupling scheme. Then, it is found that the local ff-electron states composed of the jj=7/2 octet agree quite well with those of seven ff orbitals even for a realistic value of the spin-orbit coupling. As an example of the application of the present model, we discuss low-temperature multipole states of Yb- and Tm-based filled skutterudites by analyzing multipole susceptibility of the Anderson model in the jj-jj coupling scheme with the use of a numerical renormalization group technique. From the comparison with the numerical results of the seven-orbital Anderson model, it is concluded that the multipole state is also well reproduced by the jj-jj coupling model, even when we include the hybridization between conduction and ff electrons for the realistic value of the spin-orbit coupling. Finally, we briefly discuss future applications of the present prescription for theoretical research on heavy lanthanide compounds.Comment: 12 pages, 8 figures
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