45 research outputs found

    Kenny mediates selective autophagic degradation of the IKK complex to control innate immune responses

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    Selective autophagy is a catabolic process with which cellular material is specifically targeted for degradation by lysosomes. The function of selective autophagic degradation of self-components in the regulation of innate immunity is still unclear. Here we show that Drosophila Kenny, the homologue of mammalian IKKÎł, is a selective autophagy receptor that mediates the degradation of the IB kinase complex. Selective autophagic degradation of the IÎşB kinase complex prevents constitutive activation of the immune deficiency pathway in response to commensal microbiota. We show that autophagy-deficient flies have a systemic innate immune response that promotes a hyperplasia phenotype in the midgut. Remarkably, human IKKÎł does not interact with mammalian Atg8-family proteins. Using a mathematical model, we suggest mechanisms by which pathogen selection might have driven the loss of LIR-motif functionality during evolution. Our results suggest that there may have been an autophagy-related switch during the evolution of the IKKÎł proteins in metazoans

    Shrubland primary production and soil respiration diverge along European climate gradient

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    Above- and belowground carbon (C) stores of terrestrial ecosystems are vulnerable to environmental change. Ecosystem C balances in response to environmental changes have been quantified at individual sites, but the magnitudes and directions of these responses along environmental gradients remain uncertain. Here we show the responses of ecosystem C to 8–12 years of experimental drought and night-time warming across an aridity gradient spanning seven European shrublands using indices of C assimilation (aboveground net primary production: aNPP) and soil C efflux (soil respiration: Rs). The changes of aNPP and Rs in response to drought indicated that wet systems had an overall risk of increased loss of C but drier systems did not. Warming had no consistent effect on aNPP across the climate gradient, but suppressed Rs more at the drier sites. Our findings suggest that above- and belowground C fluxes can decouple, and provide no evidence of acclimation to environmental change at a decadal timescale. aNPP and Rs especially differed in their sensitivity to drought and warming, with belowground processes being more sensitive to environmental change

    Few multiyear precipitation-reduction experiments find a shift in the productivity-precipitation relationship

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    Well-defined productivity–precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity–precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation–reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effects of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation–manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity–precipitation relationship downward the spatial fit. The majority of experiments (72%) showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation–reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with multiple, including more extreme, dry treatments, to identify the precipitation boundaries within which the current temporal fits remain valid

    Increased sensitivity to climate change in disturbed ecosystems

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    Human domination of the biosphere includes changes to disturbance regimes, which push many ecosystems towards early-successional states. Ecological theory predicts that early-successional ecosystems are more sensitive to perturbations than mature systems, but little evidence supports this relationship for the perturbation of climate change. Here we show that vegetation (abundance, species richness and species composition) across seven European shrublands is quite resistant to moderate experimental warming and drought, and responsiveness is associated with the dynamic state of the ecosystem, with recently disturbed sites responding to treatments. Furthermore, most of these responses are not rapid (2–5 years) but emerge over a longer term (7–14 years). These results suggest that successional state influences the sensitivity of ecosystems to climate change, and that ecosystems recovering from disturbances may be sensitive to even modest climatic changes. A research bias towards undisturbed ecosystems might thus lead to an underestimation of the impacts of climate change

    Evidence of titled layers in angle of arrival and Doppler beam steering power measurements

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    The results of an experiment combining Doppler beam steering (DBS) and angle of arrival (AOA) measurements are presented. Nonzero vertical beam AOAs and off zenith DBS power measurements have been attributed by various authors to the tilting of horizontal layers in the atmosphere. This study aims to directly compare vertical beam AOAs and off zenith beam power data to determine whether the relationship between the two sets of measurements is consistent with tilted layers. The results indicate that the power differences in beams at 3.6° off zenith are related to the vertical beam AOAs and that the variation of the two quantities is consistent with tilted layers being observed in all of these beams. In contrast, the power differences at 10.8° off zenith do not appear to have the same relationship to the vertical beam AOAs

    The Michael Project, 2007-2010: New Perspectives and Possibilities for Homeless Men

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    On Census night 2006, almost 105,000 people were homeless in Australia, an increase of almost five per cent over the preceding five year period. In 2008, the Australian Government set out a national approach to reducing homelessness, with headline targets of halving overall homelessness and offering supported accommodation to all rough sleepers who need it by 2020, along with a range of sub-targets (Commonwealth of Australia, 2008). Mission Australia has been supporting people experiencing homelessness since the middle of the nineteenth century. As a major national not-for-profit agency, Mission Australia has long sought to develop innovative responses to emerging social issues. With the benefit of a philanthropic donation, Mission Australia developed an innovative service pilot project, the Michael Project (2007-2010), to work towards better outcomes with men experiencing homelessness in the Sydney metropolitan region
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