151 research outputs found

    Structure and Function of the TIR Domain from the Grape NLR Protein RPV1

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    The N-terminal Toll/interleukin-1 receptor/resistance protein (TIR) domain has been shown to be both necessary and sufficient for defense signaling in the model plants flax and Arabidopsis. In examples from these organisms, TIR domain self-association is required for signaling function, albeit through distinct interfaces. Here, we investigate these properties in the TIR domain containing resistance protein RPV1 from the wild grapevine Muscadinia rotundifolia. The RPV1 TIR domain, without additional flanking sequence present, is autoactive when transiently expressed in tobacco, demonstrating that the TIR domain alone is capable of cell-death signaling. We determined the crystal structure of the RPV1 TIR domain at 2.3 Å resolution. In the crystals, the RPV1 TIR domain forms a dimer, mediated predominantly through residues in the αA and αE helices ("AE" interface). This interface is shared with the interface discovered in the dimeric complex of the TIR domains from the Arabidopsis RPS4/RRS1 resistance protein pair. We show that surface-exposed residues in the AE interface that mediate the dimer interaction in the crystals are highly conserved among plant TIR domain-containing proteins. While we were unable to demonstrate self-association of the RPV1 TIR domain in solution or using yeast 2-hybrid, mutations of surface-exposed residues in the AE interface prevent the cell-death autoactive phenotype. In addition, mutation of residues known to be important in the cell-death signaling function of the flax L6 TIR domain were also shown to be required for RPV1 TIR domain mediated cell-death. Our data demonstrate that multiple TIR domain surfaces control the cell-death function of the RPV1 TIR domain and we suggest that the conserved AE interface may have a general function in TIR-NLR signaling.This research was supported by the Australian Research Council (ARC) Discovery Projects DP120100685 and DP160102244. BK is a NHMRC Research Fellow (1003325 and 1110971). SW is funded by ARC DECRA (DE160100893)

    Patterns of Natural and Human-Caused Mortality Factors of a Rare Forest Carnivore, the Fisher (Pekania pennanti) in California.

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    Wildlife populations of conservation concern are limited in distribution, population size and persistence by various factors, including mortality. The fisher (Pekania pennanti), a North American mid-sized carnivore whose range in the western Pacific United States has retracted considerably in the past century, was proposed for threatened status protection in late 2014 under the United States Endangered Species Act by the United States Fish and Wildlife Service in its West Coast Distinct Population Segment. We investigated mortality in 167 fishers from two genetically and geographically distinct sub-populations in California within this West Coast Distinct Population Segment using a combination of gross necropsy, histology, toxicology and molecular methods. Overall, predation (70%), natural disease (16%), toxicant poisoning (10%) and, less commonly, vehicular strike (2%) and other anthropogenic causes (2%) were causes of mortality observed. We documented both an increase in mortality to (57% increase) and exposure (6%) from pesticides in fishers in just the past three years, highlighting further that toxicants from marijuana cultivation still pose a threat. Additionally, exposure to multiple rodenticides significantly increased the likelihood of mortality from rodenticide poisoning. Poisoning was significantly more common in male than female fishers and was 7 times more likely than disease to kill males. Based on necropsy findings, suspected causes of mortality based on field evidence alone tended to underestimate the frequency of disease-related mortalities. This study is the first comprehensive investigation of mortality causes of fishers and provides essential information to assist in the conservation of this species

    Forest disturbance and vector transmitted diseases in thelowland tropical rainforest of central Panama

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    objective To explore possible changes in the community attributes of haematophagous insects as afunction of forest disturbance. We compare the patterns of diversity and abundance, plus thebehavioural responses of three epidemiologically distinct vector assemblages across sites depictingvarious levels of forest cover.methods Over a 3-year period, we sampled mosquitoes, sandflies and biting-midges in forestedhabitats of central Panama. We placed CDC light traps in the forest canopy and in the understorey togather blood-seeking females.results We collected 168 405 adult haematophagous dipterans in total, including 26 genera and 86species. Pristine forest settings were always more taxonomically diverse than the disturbed forest sites,confirming that disturbance has a negative impact on species richness. Species of Phlebotominae andCulicoides were mainly classified as climax (i.e. forest specialist) or disturbance-generalist, which tendto decrease in abundance along with rising levels of disturbance. In contrast, a significant portion ofmosquito species, including primary and secondary disease vectors, was classified as colonists (i.e.disturbed-areas specialists), which tend to increase in numbers towards more disturbed forest habitats.At pristine forest, the most prevalent species of Phlebotominae and Culicoides partitioned the verticalniche by being active at the forest canopy or in the understorey; yet this pattern was less clear indisturbed habitats. Most mosquito species were not vertically stratified in their habitat preference.conclusion We posit that entomological risk and related pathogen exposure to humans is higher inpristine forest scenarios for Culicoides and Phlebotominae transmitted diseases, whereas forestdisturbance poses a higher entomological risk for mosquito-borne infections. This suggests that theDilution Effect Hypothesis (DEH) does not apply in tropical rainforests where highly abundant, yetunrecognised insect vectors and neglected zoonotic diseases occur. Comprehensive, community levelentomological surveillance is, therefore, the key for predicting potential disease spill over in scenariosof pristine forest intermixed with anthropogenic habitats. We suggest that changes in forest qualityshould also be considered when assessing arthropod-borne disease transmission risk.objective To explore possible changes in the community attributes of haematophagous insects as afunction of forest disturbance. We compare the patterns of diversity and abundance, plus thebehavioural responses of three epidemiologically distinct vector assemblages across sites depictingvarious levels of forest cover.methods Over a 3-year period, we sampled mosquitoes, sandflies and biting-midges in forestedhabitats of central Panama. We placed CDC light traps in the forest canopy and in the understorey togather blood-seeking females.results We collected 168 405 adult haematophagous dipterans in total, including 26 genera and 86species. Pristine forest settings were always more taxonomically diverse than the disturbed forest sites,confirming that disturbance has a negative impact on species richness. Species of Phlebotominae andCulicoides were mainly classified as climax (i.e. forest specialist) or disturbance-generalist, which tendto decrease in abundance along with rising levels of disturbance. In contrast, a significant portion ofmosquito species, including primary and secondary disease vectors, was classified as colonists (i.e.disturbed-areas specialists), which tend to increase in numbers towards more disturbed forest habitats.At pristine forest, the most prevalent species of Phlebotominae and Culicoides partitioned the verticalniche by being active at the forest canopy or in the understorey; yet this pattern was less clear indisturbed habitats. Most mosquito species were not vertically stratified in their habitat preference.conclusion We posit that entomological risk and related pathogen exposure to humans is higher inpristine forest scenarios for Culicoides and Phlebotominae transmitted diseases, whereas forestdisturbance poses a higher entomological risk for mosquito-borne infections. This suggests that theDilution Effect Hypothesis (DEH) does not apply in tropical rainforests where highly abundant, yetunrecognised insect vectors and neglected zoonotic diseases occur. Comprehensive, community levelentomological surveillance is, therefore, the key for predicting potential disease spill over in scenariosof pristine forest intermixed with anthropogenic habitats. We suggest that changes in forest qualityshould also be considered when assessing arthropod-borne disease transmission risk

    Gender Differences in Russian Colour Naming

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    In the present study we explored Russian colour naming in a web-based psycholinguistic experiment (http://www.colournaming.com). Colour singletons representing the Munsell Color Solid (N=600 in total) were presented on a computer monitor and named using an unconstrained colour-naming method. Respondents were Russian speakers (N=713). For gender-split equal-size samples (NF=333, NM=333) we estimated and compared (i) location of centroids of 12 Russian basic colour terms (BCTs); (ii) the number of words in colour descriptors; (iii) occurrences of BCTs most frequent non-BCTs. We found a close correspondence between females’ and males’ BCT centroids. Among individual BCTs, the highest inter-gender agreement was for seryj ‘grey’ and goluboj ‘light blue’, while the lowest was for sinij ‘dark blue’ and krasnyj ‘red’. Females revealed a significantly richer repertory of distinct colour descriptors, with great variety of monolexemic non-BCTs and “fancy” colour names; in comparison, males offered relatively more BCTs or their compounds. Along with these measures, we gauged denotata of most frequent CTs, reflected by linguistic segmentation of colour space, by employing a synthetic observer trained by gender-specific responses. This psycholinguistic representation revealed females’ more refined linguistic segmentation, compared to males, with higher linguistic density predominantly along the redgreen axis of colour space

    Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient

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    We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

    Spectroscopy from Lyman alpha to [O III] 5007 of a Triply Imaged Magnified Galaxy at Redshift z = 9.5

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    Given their extremely faint apparent brightness, the nature of the first galaxies and how they reionized the Universe's gas are not yet understood. Here we report the discovery, in James Webb Space Telescope (JWST) imaging, of a highly magnified, low-mass (log(M_*/M_sol)=7.70^{+0.11}_{-0.09}) galaxy visible when the Universe was only 510 Myr old, and follow-up prism spectroscopy of the galaxy extending from Lyman alpha to [O III] 5007 in its rest frame. Our JWST spectrum provides [O III] 5007 and H beta detections with a respective signal-to-noise ratio (S/N) of 40 and 13, as well as six additional lines with S/N > 3. These emission lines yield a redshift of z=9.51 and star-formation rate of 2.12 +- 0.53 solar masses per year. The galaxy's large inferred value of [O III]/[O II] = 16 +- 6 suggests that this galaxy has an escape fraction of ionizing radiation larger than 10%, indicating that a population of similar objects could contribute substantially to the reionization budget. Using multiple techniques, we infer a gas oxygen abundance of 12 + log(O/H) = 7.48 +- 0.05 dex, consistent within 2 sigma of the mass-metallicity relation observed for dwarf galaxies in the local Universe

    The XMM Cluster Survey: X-ray analysis methodology

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    The XMM Cluster Survey (XCS) is a serendipitous search for galaxy clusters using all publicly available data in the XMM-Newton Science Archive. Its main aims are to measure cosmological parameters and trace the evolution of X-ray scaling relations. In this paper we describe the data processing methodology applied to the 5,776 XMM observations used to construct the current XCS source catalogue. A total of 3,675 > 4-sigma cluster candidates with > 50 background-subtracted X-ray counts are extracted from a total non-overlapping area suitable for cluster searching of 410 deg^2. Of these, 993 candidates are detected with > 300 background-subtracted X-ray photon counts, and we demonstrate that robust temperature measurements can be obtained down to this count limit. We describe in detail the automated pipelines used to perform the spectral and surface brightness fitting for these candidates, as well as to estimate redshifts from the X-ray data alone. A total of 587 (122) X-ray temperatures to a typical accuracy of < 40 (< 10) per cent have been measured to date. We also present the methodology adopted for determining the selection function of the survey, and show that the extended source detection algorithm is robust to a range of cluster morphologies by inserting mock clusters derived from hydrodynamical simulations into real XMM images. These tests show that the simple isothermal beta-profiles is sufficient to capture the essential details of the cluster population detected in the archival XMM observations. The redshift follow-up of the XCS cluster sample is presented in a companion paper, together with a first data release of 503 optically-confirmed clusters.Comment: MNRAS accepted, 45 pages, 38 figures. Our companion paper describing our optical analysis methodology and presenting a first set of confirmed clusters has now been submitted to MNRA
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