| 1. |
- Abe, H., et al.
(författare)
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Gamma-ray observations of MAXI J1820+070 during the 2018 outburst
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 517:4, s. 4736-4751
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Tidskriftsartikel (refereegranskat)abstract
- MAXIJ1820+070 is a low-mass X-ray binary with a black hole (BH) as a compact object. This binary underwent an exceptionally bright X-ray outburst from 2018 March to October, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 h of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy (HE) gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to similar to 500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential HE and very-HE gamma-ray emitting region should be located at a distance from the BH ranging between 10(11) and 10(13) cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA.
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| 2. |
- De Angelis, A., et al.
(författare)
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Science with e-ASTROGAM A space mission for MeV-GeV gamma-ray astrophysics
- 2018
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Ingår i: Journal of High Energy Astrophysics. - : Elsevier. - 2214-4048 .- 2214-4056. ; 19, s. 1-106
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Tidskriftsartikel (refereegranskat)abstract
- e-ASTROGAM ('enhanced ASTROGAM') is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV - the lower energy limit can be pushed to energies as low as 150 keV for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and LISA.
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| 3. |
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| 4. |
- Correa, D. F., et al.
(författare)
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Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates
- 2023
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 32:1, s. 49-69
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Tidskriftsartikel (refereegranskat)abstract
- Aim To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period Tree-inventory plots established between 1934 and 2019. Major taxa studied Trees with a diameter at breast height (DBH) >= 9.55 cm. Location Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types.
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| 5. |
- Morales, J. C., et al.
(författare)
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A giant exoplanet orbiting a very-low-mass star challenges planet formation models
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 365:6460, s. 1441-1445
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Tidskriftsartikel (refereegranskat)abstract
- Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.
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| 6. |
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| 7. |
- Horwich, A, et al.
(författare)
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EAU–ESMO consensus statements on the management of advanced and variant bladder cancer - an international collaborative multi-stakeholder effort : under the auspices of the EAU and ESMO Guidelines Committees
- 2019
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Ingår i: Annals of Oncology. - : Oxford University Press. - 0923-7534 .- 1569-8041. ; 30:11, s. 1697-1727
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although guidelines exist for advanced and variant bladder cancer management, evidence is limited/conflicting in some areas and the optimal approach remains controversial.OBJECTIVE: To bring together a large multidisciplinary group of experts to develop consensus statements on controversial topics in bladder cancer management.DESIGN: A steering committee compiled proposed statements regarding advanced and variant bladder cancer management which were assessed by 113 experts in a Delphi survey. Statements not reaching consensus were reviewed; those prioritised were revised by a panel of 45 experts before voting during a consensus conference.SETTING: Online Delphi survey and consensus conference.PARTICIPANTS: The European Association of Urology (EAU), the European Society for Medical Oncology (ESMO), experts in bladder cancer management.OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Statements were ranked by experts according to their level of agreement: 1-3 (disagree), 4-6 (equivocal), 7-9 (agree). A priori (level 1) consensus was defined as ≥70% agreement and ≤15% disagreement, or vice versa. In the Delphi survey, a second analysis was restricted to stakeholder group(s) considered to have adequate expertise relating to each statement (to achieve level 2 consensus).RESULTS AND LIMITATIONS: Overall, 116 statements were included in the Delphi survey. Of these, 33 (28%) statements achieved level 1 consensus and 49 (42%) statements achieved level 1 or 2 consensus. At the consensus conference, 22 of 27 (81%) statements achieved consensus. These consensus statements provide further guidance across a broad range of topics, including the management of variant histologies, the role/limitations of prognostic biomarkers in clinical decision making, bladder preservation strategies, modern radiotherapy techniques, the management of oligometastatic disease and the evolving role of checkpoint inhibitor therapy in metastatic disease.CONCLUSIONS: These consensus statements provide further guidance on controversial topics in advanced and variant bladder cancer management until a time where further evidence is available to guide our approach.
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| 8. |
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| 9. |
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| 10. |
- Poyatos, R., et al.
(författare)
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Global transpiration data from sap flow measurements: the SAPFLUXNET database
- 2021
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 13:6, s. 2607-2649
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Tidskriftsartikel (refereegranskat)abstract
- Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.
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| 11. |
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| 12. |
- Bethlehem, RAI, et al.
(författare)
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Brain charts for the human lifespan
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 604:79057906, s. 525-
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Tidskriftsartikel (refereegranskat)abstract
- Over the past few decades, neuroimaging has become a ubiquitous tool in basic research and clinical studies of the human brain. However, no reference standards currently exist to quantify individual differences in neuroimaging metrics over time, in contrast to growth charts for anthropometric traits such as height and weight1. Here we assemble an interactive open resource to benchmark brain morphology derived from any current or future sample of MRI data (http://www.brainchart.io/). With the goal of basing these reference charts on the largest and most inclusive dataset available, acknowledging limitations due to known biases of MRI studies relative to the diversity of the global population, we aggregated 123,984 MRI scans, across more than 100 primary studies, from 101,457 human participants between 115 days post-conception to 100 years of age. MRI metrics were quantified by centile scores, relative to non-linear trajectories2 of brain structural changes, and rates of change, over the lifespan. Brain charts identified previously unreported neurodevelopmental milestones3, showed high stability of individuals across longitudinal assessments, and demonstrated robustness to technical and methodological differences between primary studies. Centile scores showed increased heritability compared with non-centiled MRI phenotypes, and provided a standardized measure of atypical brain structure that revealed patterns of neuroanatomical variation across neurological and psychiatric disorders. In summary, brain charts are an essential step towards robust quantification of individual variation benchmarked to normative trajectories in multiple, commonly used neuroimaging phenotypes.
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| 13. |
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| 14. |
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| 15. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 16. |
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| 17. |
- Pfaller, M.A., et al.
(författare)
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Twelve years of fluconazole in clinical practice : Global-trends in species distribution and fluconazole susceptibility of bloodstream isolates of Candida
- 2004
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Ingår i: Clinical Microbiology and Infection. - : Elsevier BV. - 1198-743X .- 1469-0691. ; 10:SUPPL. 1, s. 11-23
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Tidskriftsartikel (refereegranskat)abstract
- We determined the species distribution and in-vitro susceptibility of 6082 bloodstream infection (BSI) isolates of Candida spp. collected from 250 medical centres in 32 nations over a 10-year period from 1992 through 2001. The species included 3401 C. albicans, 984 C. glabrata, 796 C. parapsilosis, 585 C. tropicalis, 153 C. krusei, 67 C. lusitaniae, 48 C. guilliermondii, 10 C. famata, 10 C. kefyr, six C. pelliculosa, five C. rugosa, four C. lipolytica, three C. dubliniensis, three C. inconspicua, two C. sake and one isolate each of C. lambica, C. norvegensis and C. zeylanoides. Minimum inhibitory concentration determinations were made using the National Committee for Clinical Laboratory Standards reference broth microdilution method. Variation in the rank order and frequency of the different species of Candida was observed over time and by geographic area. The proportion of BSI due to C. albicans and C. glabrata increased and C. parapsilosis decreased over time in Canada, the USA and Europe. C. glabrata was an infrequent cause of BSI in Latin America and the Asia-Pacific region. Very little variation in fluconazole susceptibility was observed among isolates of C. albicans, C. tropicalis and C. parapsilosis. These species accounted for 78% of all BSI and remained highly susceptible (91-100% susceptible) to fluconazole from 1992 to 2001 irrespective of geographic origin. The prevalence of fluconazole resistance among C. glabrata isolates was variable both over time and among the various countries and regions. Resistance to fluconazole among C. glabrata isolates was greatest in the USA and varied by US census region (range 0-23%). These observations are generally encouraging relative to the sustained usefulness of fluconazole as a systemically active antifungal agent for the treatment of candida BSI. © 2004 Copyright by the European Society of Clinical Microbiology and Infectious Diseases.
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| 18. |
- Perez-Nadales, Elena, et al.
(författare)
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Predictors of mortality in solid organ transplant recipients with bloodstream infections due to carbapenemase-producing Enterobacterales : The impact of cytomegalovirus disease and lymphopenia
- 2020
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Ingår i: American Journal of Transplantation. - : WILEY. - 1600-6135 .- 1600-6143. ; 20:6, s. 1629-1641
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Tidskriftsartikel (refereegranskat)abstract
- Treatment of carbapenemase-producing Enterobacterales bloodstream infections in solid organ transplant recipients is challenging. The objective of this study was to develop a specific score to predict mortality in solid organ transplant recipients with carbapenemase-producing Enterobacterales bloodstream infections. A multinational, retrospective (2004-2016) cohort study (INCREMENT-SOT, ClinicalTrials.gov NCT02852902) was performed. The main outcome variable was 30-day all-cause mortality. The INCREMENT-SOT-CPE score was developed using logistic regression. The global cohort included 216 patients. The final logistic regression model included the following variables: INCREMENT-CPE mortality score >= 8 (8 points), no source control (3 points), inappropriate empirical therapy (2 points), cytomegalovirus disease (7 points), lymphopenia (4 points), and the interaction between INCREMENT-CPE score >= 8 and CMV disease (minus 7 points). This score showed an area under the receiver operating characteristic curve of 0.82 (95% confidence interval [CI] 0.76-0.88) and classified patients into 3 strata: 0-7 (low mortality), 8-11 (high mortality), and 12-17 (very-high mortality). We performed a stratified analysis of the effect of monotherapy vs combination therapy among 165 patients who received appropriate therapy. Monotherapy was associated with higher mortality only in the very-high (adjusted hazard ratio [HR] 2.82, 95% CI 1.13-7.06, P = .03) and high (HR 9.93, 95% CI 2.08-47.40, P = .004) mortality risk strata. A score-based algorithm is provided for therapy guidance.
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| 19. |
- Nguyen, Thanh N, et al.
(författare)
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Global Impact of the COVID-19 Pandemic on Stroke Volumes and Cerebrovascular Events: A 1-Year Follow-up.
- 2023
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Ingår i: Neurology. - 1526-632X. ; 100:4
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Tidskriftsartikel (refereegranskat)abstract
- Declines in stroke admission, IV thrombolysis (IVT), and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought to measure the effect of the COVID-19 pandemic on the volumes of stroke admissions, intracranial hemorrhage (ICH), IVT, and mechanical thrombectomy over a 1-year period at the onset of the pandemic (March 1, 2020, to February 28, 2021) compared with the immediately preceding year (March 1, 2019, to February 29, 2020).We conducted a longitudinal retrospective study across 6 continents, 56 countries, and 275 stroke centers. We collected volume data for COVID-19 admissions and 4 stroke metrics: ischemic stroke admissions, ICH admissions, IVT treatments, and mechanical thrombectomy procedures. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases.There were 148,895 stroke admissions in the 1 year immediately before compared with 138,453 admissions during the 1-year pandemic, representing a 7% decline (95% CI [95% CI 7.1-6.9]; p < 0.0001). ICH volumes declined from 29,585 to 28,156 (4.8% [5.1-4.6]; p < 0.0001) and IVT volume from 24,584 to 23,077 (6.1% [6.4-5.8]; p < 0.0001). Larger declines were observed at high-volume compared with low-volume centers (all p < 0.0001). There was no significant change in mechanical thrombectomy volumes (0.7% [0.6-0.9]; p = 0.49). Stroke was diagnosed in 1.3% [1.31-1.38] of 406,792 COVID-19 hospitalizations. SARS-CoV-2 infection was present in 2.9% ([2.82-2.97], 5,656/195,539) of all stroke hospitalizations.There was a global decline and shift to lower-volume centers of stroke admission volumes, ICH volumes, and IVT volumes during the 1st year of the COVID-19 pandemic compared with the prior year. Mechanical thrombectomy volumes were preserved. These results suggest preservation in the stroke care of higher severity of disease through the first pandemic year.This study is registered under NCT04934020.
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| 20. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 21. |
- Householder, John Ethan, et al.
(författare)
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One sixth of Amazonian tree diversity is dependent on river floodplains
- 2024
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Ingår i: NATURE ECOLOGY & EVOLUTION. - 2397-334X.
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Tidskriftsartikel (refereegranskat)abstract
- Amazonia's floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region's floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon's tree diversity and its function.
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| 22. |
- Luize, Bruno Garcia, et al.
(författare)
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Geography and ecology shape the phylogenetic composition of Amazonian tree communities
- 2024
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Ingår i: JOURNAL OF BIOGEOGRAPHY. - 0305-0270 .- 1365-2699.
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and v & aacute;rzea forest types, the phylogenetic composition varies by geographic region, but the igap & oacute; and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R-2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R-2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions.
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| 23. |
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| 24. |
- ter Steege, Hans, et al.
(författare)
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Mapping density, diversity and species-richness of the Amazon tree flora
- 2023
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Ingår i: COMMUNICATIONS BIOLOGY. - 2399-3642. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution. A study mapping the tree species richness in Amazonian forests shows that soil type exerts a strong effect on species richness, probably caused by the areas of these forest types. Cumulative water deficit, tree density and temperature seasonality affect species richness at a regional scale.
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| 28. |
- Lazaridis, Iosif, et al.
(författare)
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Ancient human genomes suggest three ancestral populations for present-day Europeans
- 2014
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 513:7518, s. 409-
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Tidskriftsartikel (refereegranskat)abstract
- We sequenced the genomes of a similar to 7,000-year-old farmer from Germany and eight similar to 8,000-year-old hunter-gatherers from Luxembourg and Sweden. We analysed these and other ancient genomes(1-4) with 2,345 contemporary humans to show that most present-day Europeans derive from at least three highly differentiated populations: west European hunter-gatherers, who contributed ancestry to all Europeans but not to Near Easterners; ancient north Eurasians related to Upper Palaeolithic Siberians(3), who contributed to both Europeans and Near Easterners; and early European farmers, who were mainly of Near Eastern origin but also harboured west European hunter-gatherer related ancestry. We model these populations' deep relationships and show that early European farmers had similar to 44% ancestry from a 'basal Eurasian' population that split before the diversification of other non-African lineages.
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| 29. |
- Matalonga, L, et al.
(författare)
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Solving patients with rare diseases through programmatic reanalysis of genome-phenome data
- 2021
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Ingår i: European journal of human genetics : EJHG. - : Springer Science and Business Media LLC. - 1476-5438 .- 1018-4813. ; 29:9, s. 1337-1347
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Tidskriftsartikel (refereegranskat)abstract
- Reanalysis of inconclusive exome/genome sequencing data increases the diagnosis yield of patients with rare diseases. However, the cost and efforts required for reanalysis prevent its routine implementation in research and clinical environments. The Solve-RD project aims to reveal the molecular causes underlying undiagnosed rare diseases. One of the goals is to implement innovative approaches to reanalyse the exomes and genomes from thousands of well-studied undiagnosed cases. The raw genomic data is submitted to Solve-RD through the RD-Connect Genome-Phenome Analysis Platform (GPAP) together with standardised phenotypic and pedigree data. We have developed a programmatic workflow to reanalyse genome-phenome data. It uses the RD-Connect GPAP’s Application Programming Interface (API) and relies on the big-data technologies upon which the system is built. We have applied the workflow to prioritise rare known pathogenic variants from 4411 undiagnosed cases. The queries returned an average of 1.45 variants per case, which first were evaluated in bulk by a panel of disease experts and afterwards specifically by the submitter of each case. A total of 120 index cases (21.2% of prioritised cases, 2.7% of all exome/genome-negative samples) have already been solved, with others being under investigation. The implementation of solutions as the one described here provide the technical framework to enable periodic case-level data re-evaluation in clinical settings, as recommended by the American College of Medical Genetics.
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| 30. |
- Barbeiro, A. R., et al.
(författare)
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3D VMAT Verification Based on Monte Carlo Log File Simulation with Experimental Feedback from Film Dosimetry
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- A model based on a specific phantom, called QuAArC, has been designed for the evaluation of planning and verification systems of complex radiotherapy treatments, such as volumetric modulated arc therapy (VMAT). This model uses the high accuracy provided by the Monte Carlo (MC) simulation of log files and allows the experimental feedback from the high spatial resolution of films hosted in QuAArC. This cylindrical phantom was specifically designed to host films rolled at different radial distances able to take into account the entrance fluence and the 3D dose distribution. Ionization chamber measurements are also included in the feedback process for absolute dose considerations. In this way, automated MC simulation of treatment log files is implemented to calculate the actual delivery geometries, while the monitor units are experimentally adjusted to reconstruct the dose-volume histogram (DVH) on the patient CT. Prostate and head and neck clinical cases, previously planned with Monaco and Pinnacle treatment planning systems and verified with two different commercial systems (Delta4 and COMPASS), were selected in order to test operational feasibility of the proposed model. The proper operation of the feedback procedure was proved through the achieved high agreement between reconstructed dose distributions and the film measurements (global gamma passing rates > 90% for the 2%/2 mm criteria). The necessary discretization level of the log file for dose calculation and the potential mismatching between calculated control points and detection grid in the verification process were discussed. Besides the effect of dose calculation accuracy of the analytic algorithm implemented in treatment planning systems for a dynamic technique, it was discussed the importance of the detection density level and its location in VMAT specific phantom to obtain a more reliable DVH in the patient CT. The proposed model also showed enough robustness and efficiency to be considered as a pre-treatment VMAT verification system.
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| 31. |
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| 32. |
- Bellocchi, C, et al.
(författare)
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Identification of a Shared Microbiomic and Metabolomic Profile in Systemic Autoimmune Diseases
- 2019
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Ingår i: Journal of clinical medicine. - : MDPI AG. - 2077-0383. ; 8:9
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Tidskriftsartikel (refereegranskat)abstract
- Dysbiosis has been described in systemic autoimmune diseases (SADs), including systemic lupus erythematosus (SLE), Sjögren’s syndrome (SjS), and primary anti-phosholipid syndrome (PAPS), however the biological implications of these associations are often elusive. Stool and plasma samples from 114 subjects, including in SLE (n = 27), SjS (n = 23), PAPs (n = 11) and undifferentiated connective tissue (UCTD, n = 26) patients, and geographically-matched healthy controls (HCs, n = 27), were collected for microbiome (16s rRNA gene sequencing) and metabolome (high-performance liquid chromatography coupled to mass spectrometry) analysis to identify shared characteristics across diseases. Out of 130 identified microbial genera, a subset of 29 bacteria was able to differentiate study groups (area under receiver operating characteristics (AUROC) = 0.730 ± 0.025). A fair classification was obtained with a subset of 41 metabolic peaks out of 254 (AUROC = 0.748 ± 0.021). In both models, HCs were well separated from SADs, while UCTD largely overlapped with the other diseases. In all of the SADs pro-tolerogenic bacteria were reduced, while pathobiont genera were increased. Metabolic alterations included two clusters comprised of: (a) members of the acylcarnitine family, positively correlating with a Prevotella-enriched cluster and negatively correlating with a butyrate-producing bacteria-enriched cluster; and (b) phospholipids, negatively correlating with butyrate-producing bacteria. These findings demonstrate a strong interaction between intestinal microbiota and metabolic function in patients with SADs.
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
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| 38. |
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| 39. |
- Christodoulou, C., et al.
(författare)
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Tuning the work function of graphene-on-quartz with a high weight molecular acceptor
- 2014
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:9, s. 4784-4790
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Tidskriftsartikel (refereegranskat)abstract
- Ultraviolet and X-ray photoelectron spectroscopies in combination with density functional theory (DFT) calculations were used to study the change in the work function (Φ) of graphene, supported by quartz, as induced by adsorption of hexaazatriphenylene-hexacarbonitrile (HATCN). Near edge X-ray absorption fine structure spectroscopy (NEXAFS) and DFT modeling show that a molecular-density-dependent reorientation of HATCN from a planar to a vertically inclined adsorption geometry occurs upon increasing surface coverage. This, in conjunction with the orientation-dependent magnitude of the interface dipole, allows one to explain the evolution of graphene Φ from 4.5 eV up to 5.7 eV, rendering the molecularly modified graphene-on-quartz a highly suitable hole injection electrode.
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| 40. |
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| 41. |
- Hunter, KE, et al.
(författare)
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Transforming Obesity Prevention for CHILDren (TOPCHILD) Collaboration: protocol for a systematic review with individual participant data meta-analysis of behavioural interventions for the prevention of early childhood obesity
- 2022
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 12:1, s. e048166-
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Tidskriftsartikel (refereegranskat)abstract
- Behavioural interventions in early life appear to show some effect in reducing childhood overweight and obesity. However, uncertainty remains regarding their overall effectiveness, and whether effectiveness differs among key subgroups. These evidence gaps have prompted an increase in very early childhood obesity prevention trials worldwide. Combining the individual participant data (IPD) from these trials will enhance statistical power to determine overall effectiveness and enable examination of individual and trial-level subgroups. We present a protocol for a systematic review with IPD meta-analysis to evaluate the effectiveness of obesity prevention interventions commencing antenatally or in the first year after birth, and to explore whether there are differential effects among key subgroups.Methods and analysisSystematic searches of Medline, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycInfo and trial registries for all ongoing and completed randomised controlled trials evaluating behavioural interventions for the prevention of early childhood obesity have been completed up to March 2021 and will be updated annually to include additional trials. Eligible trialists will be asked to share their IPD; if unavailable, aggregate data will be used where possible. An IPD meta-analysis and a nested prospective meta-analysis will be performed using methodologies recommended by the Cochrane Collaboration. The primary outcome will be body mass index z-score at age 24±6 months using WHO Growth Standards, and effect differences will be explored among prespecified individual and trial-level subgroups. Secondary outcomes include other child weight-related measures, infant feeding, dietary intake, physical activity, sedentary behaviours, sleep, parenting measures and adverse events.Ethics and disseminationApproved by The University of Sydney Human Research Ethics Committee (2020/273) and Flinders University Social and Behavioural Research Ethics Committee (HREC CIA2133-1). Results will be relevant to clinicians, child health services, researchers, policy-makers and families, and will be disseminated via publications, presentations and media releases.PROSPERO registration numberCRD42020177408.
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| 42. |
- Johnson, BJ, et al.
(författare)
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Unpacking the behavioural components and delivery features of early childhood obesity prevention interventions in the TOPCHILD Collaboration: a systematic review and intervention coding protocol
- 2022
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 12:1, s. e048165-
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about how early (eg, commencing antenatally or in the first 12 months after birth) obesity prevention interventions seek to change behaviour and which components are or are not effective. This study aims to (1) characterise early obesity prevention interventions in terms of target behaviours, delivery features and behaviour change techniques (BCTs), (2) explore similarities and differences in BCTs used to target behaviours and (3) explore effectiveness of intervention components in preventing childhood obesity.Methods and analysisAnnual comprehensive systematic searches will be performed in Epub Ahead of Print/MEDLINE, Embase, Cochrane (CENTRAL), CINAHL, PsycINFO, as well as clinical trial registries. Eligible randomised controlled trials of behavioural interventions to prevent childhood obesity commencing antenatally or in the first year after birth will be invited to join the Transforming Obesity in CHILDren Collaboration. Standard ontologies will be used to code target behaviours, delivery features and BCTs in both published and unpublished intervention materials provided by trialists. Narrative syntheses will be performed to summarise intervention components and compare applied BCTs by types of target behaviours. Exploratory analyses will be undertaken to assess effectiveness of intervention components.Ethics and disseminationThe study has been approved by The University of Sydney Human Research Ethics Committee (project no. 2020/273) and Flinders University Social and Behavioural Research Ethics Committee (project no. HREC CIA2133-1). The study’s findings will be disseminated through peer-reviewed publications, conference presentations and targeted communication with key stakeholders.PROSPERO registration numberCRD42020177408.
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| 43. |
- Jung, R. E., et al.
(författare)
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Effect of peri-implant mucosal thickness on esthetic outcomes and the efficacy of soft tissue augmentation procedures: Consensus report of group 2 of the SEPA/DGI/OF workshop
- 2022
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Ingår i: Clinical Oral Implants Research. - : Wiley. - 0905-7161 .- 1600-0501. ; 33, s. 100-108
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Tidskriftsartikel (refereegranskat)abstract
- Objectives The aim of this study was to comprehensively assess the literature in terms of the effect of peri-implant mucosal thickness on esthetic outcomes and the efficacy of soft tissue augmentation procedures to increase the mucosal thickness with autogenous grafts or soft tissue substitutes. Material and methods Two systematic reviews (SR) were performed prior to the consensus meeting to assess the following questions. Review 1, focused question: In systemically healthy patients with an implant-supported fixed prosthesis, what is the influence of thin as compared to thick peri-implant mucosa on esthetic outcomes? Review 2, focused question 1: In systemically healthy humans with at least one dental implant (immediate or staged implant), what is the efficacy of connective tissue graft (CTG), as compared to absence of a soft tissue grafting procedure, in terms of gain in peri-implant soft tissue thickness (STT) reported by randomized controlled clinical trials (RCTs) or controlled clinical trials (CCTs)? Review 2, focused question 2: In systemically healthy humans with at least one dental implant (immediate or staged implant), what is the efficacy of CTG, as compared to soft tissue substitutes, in terms of gain in peri-implant STT reported by RCTs or CCTs? The outcomes of the two SRs, the consensus statements, the clinical implications, and the research recommendations were discussed and subsequently approved at the consensus meeting during the group and plenary sessions. Conclusions There was a tendency of superior esthetic outcomes in the presence of a thick mucosa. The connective tissue graft remains the standard of care in terms of increasing mucosa thickness.
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| 44. |
- Laurie, Steven, et al.
(författare)
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The RD-Connect Genome-Phenome Analysis Platform : Accelerating diagnosis, research, and gene discovery for rare diseases
- 2022
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Ingår i: Human Mutation. - : John Wiley & Sons. - 1059-7794 .- 1098-1004. ; 43:6, s. 717-733
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Tidskriftsartikel (refereegranskat)abstract
- Rare disease patients are more likely to receive a rapid molecular diagnosis nowadays thanks to the wide adoption of next-generation sequencing. However, many cases remain undiagnosed even after exome or genome analysis, because the methods used missed the molecular cause in a known gene, or a novel causative gene could not be identified and/or confirmed. To address these challenges, the RD-Connect Genome-Phenome Analysis Platform (GPAP) facilitates the collation, discovery, sharing, and analysis of standardized genome-phenome data within a collaborative environment. Authorized clinicians and researchers submit pseudonymised phenotypic profiles encoded using the Human Phenotype Ontology, and raw genomic data which is processed through a standardized pipeline. After an optional embargo period, the data are shared with other platform users, with the objective that similar cases in the system and queries from peers may help diagnose the case. Additionally, the platform enables bidirectional discovery of similar cases in other databases from the Matchmaker Exchange network. To facilitate genome-phenome analysis and interpretation by clinical researchers, the RD-Connect GPAP provides a powerful user-friendly interface and leverages tens of information sources. As a result, the resource has already helped diagnose hundreds of rare disease patients and discover new disease causing genes.
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| 45. |
- Linares, Mathieu, et al.
(författare)
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On the interface dipole at the pentacene-fullerene heterojunction : A theoretical study
- 2010
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:7, s. 3215-3224
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure at organic/organic interfaces plays a key role, among others, in defining the quantum efficiency of organics-based photovoltaic cells. Here, we perform quantum-chemical and microelectrostatic calculations on molecular aggregates of various sizes and shapes to characterize the interfacial dipole moment at pentacene/C60 heterojunctions. The results show that the interfacial dipole mostly originates in polarization effects due to the asymmetry in the multipolar expansion of the electronic density distribution between the interacting molecules, rather than in a charge transfer from donor to acceptor. The local dipole is found to fluctuate in sign and magnitude over the interface and appears as a sensitive probe of the relative arrangements of the pentacene and C60 molecules (and of the resulting local electrical fields sensed by the molecular units).
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| 46. |
- Witjes, J. Alfred, et al.
(författare)
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EAU-ESMO Consensus Statements on the Management of Advanced and Variant Bladder Cancer – An International Collaborative Multistakeholder Effort : Under the Auspices of the EAU-ESMO Guidelines Committees
- 2020
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Ingår i: European Urology. - : Elsevier. - 0302-2838 .- 1873-7560. ; 77:2, s. 223-250
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although guidelines exist for advanced and variant bladder cancer management, evidence is limited/conflicting in some areas and the optimal approach remains controversial.OBJECTIVE: To bring together a large multidisciplinary group of experts to develop consensus statements on controversial topics in bladder cancer management.DESIGN: A steering committee compiled proposed statements regarding advanced and variant bladder cancer management which were assessed by 113 experts in a Delphi survey. Statements not reaching consensus were reviewed; those prioritised were revised by a panel of 45 experts prior to voting during a consensus conference.SETTING: Online Delphi survey and consensus conference.PARTICIPANTS: The European Association of Urology (EAU), the European Society for Medical Oncology (ESMO), experts in bladder cancer management.OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Statements were ranked by experts according to their level of agreement: 1-3 (disagree), 4-6 (equivocal), and 7-9 (agree). A priori (level 1) consensus was defined as ≥70% agreement and ≤15% disagreement, or vice versa. In the Delphi survey, a second analysis was restricted to stakeholder group(s) considered to have adequate expertise relating to each statement (to achieve level 2 consensus).RESULTS AND LIMITATIONS: Overall, 116 statements were included in the Delphi survey. Of these statements, 33 (28%) achieved level 1 consensus and 49 (42%) achieved level 1 or 2 consensus. At the consensus conference, 22 of 27 (81%) statements achieved consensus. These consensus statements provide further guidance across a broad range of topics, including the management of variant histologies, the role/limitations of prognostic biomarkers in clinical decision making, bladder preservation strategies, modern radiotherapy techniques, the management of oligometastatic disease, and the evolving role of checkpoint inhibitor therapy in metastatic disease.CONCLUSIONS: These consensus statements provide further guidance on controversial topics in advanced and variant bladder cancer management until a time when further evidence is available to guide our approach.PATIENT SUMMARY: This report summarises findings from an international, multistakeholder project organised by the EAU and ESMO. In this project, a steering committee identified areas of bladder cancer management where there is currently no good-quality evidence to guide treatment decisions. From this, they developed a series of proposed statements, 71 of which achieved consensus by a large group of experts in the field of bladder cancer. It is anticipated that these statements will provide further guidance to health care professionals and could help improve patient outcomes until a time when good-quality evidence is available.
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| 47. |
- Aevarsson, Arnthór, et al.
(författare)
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Going to extremes - a metagenomic journey into the dark matter of life
- 2021
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Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968. ; 368:12
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Forskningsöversikt (refereegranskat)abstract
- The Virus-X-Viral Metagenomics for Innovation Value-project was a scientific expedition to explore and exploit uncharted territory of genetic diversity in extreme natural environments such as geothermal hot springs and deep-sea ocean ecosystems. Specifically, the project was set to analyse and exploit viral metagenomes with the ultimate goal of developing new gene products with high innovation value for applications in biotechnology, pharmaceutical, medical, and the life science sectors. Viral gene pool analysis is also essential to obtain fundamental insight into ecosystem dynamics and to investigate how viruses influence the evolution of microbes and multicellular organisms. The Virus-X Consortium, established in 2016, included experts from eight European countries. The unique approach based on high throughput bioinformatics technologies combined with structural and functional studies resulted in the development of a biodiscovery pipeline of significant capacity and scale. The activities within the Virus-X consortium cover the entire range from bioprospecting and methods development in bioinformatics to protein production and characterisation, with the final goal of translating our results into new products for the bioeconomy. The significant impact the consortium made in all of these areas was possible due to the successful cooperation between expert teams that worked together to solve a complex scientific problem using state-of-the-art technologies as well as developing novel tools to explore the virosphere, widely considered as the last great frontier of life.
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| 48. |
- Ahlqvist, Josefin, et al.
(författare)
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Crystal structure and initial characterization of a novel archaeal-like Holliday junction-resolving enzyme from Thermus thermophilus phage Tth15-6
- 2022
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Ingår i: Acta crystallographica. Section D, Structural biology. - 2059-7983. ; 78:Pt 2, s. 212-227
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Tidskriftsartikel (refereegranskat)abstract
- This study describes the production, characterization and structure determination of a novel Holliday junction-resolving enzyme. The enzyme, termed Hjc_15-6, is encoded in the genome of phage Tth15-6, which infects Thermus thermophilus. Hjc_15-6 was heterologously produced in Escherichia coli and high yields of soluble and biologically active recombinant enzyme were obtained in both complex and defined media. Amino-acid sequence and structure comparison suggested that the enzyme belongs to a group of enzymes classified as archaeal Holliday junction-resolving enzymes, which are typically divalent metal ion-binding dimers that are able to cleave X-shaped dsDNA-Holliday junctions (Hjs). The crystal structure of Hjc_15-6 was determined to 2.5 Å resolution using the selenomethionine single-wavelength anomalous dispersion method. To our knowledge, this is the first crystal structure of an Hj-resolving enzyme originating from a bacteriophage that can be classified as an archaeal type of Hj-resolving enzyme. As such, it represents a new fold for Hj-resolving enzymes from phages. Characterization of the structure of Hjc_15-6 suggests that it may form a dimer, or even a homodimer of dimers, and activity studies show endonuclease activity towards Hjs. Furthermore, based on sequence analysis it is proposed that Hjc_15-6 has a three-part catalytic motif corresponding to E-SD-EVK, and this motif may be common among other Hj-resolving enzymes originating from thermophilic bacteriophages.
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| 49. |
- Ahlqvist, Josefin, et al.
(författare)
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Crystal structure of DNA polymerase I from Thermus phage G20c
- 2022
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Ingår i: Acta crystallographica. Section D, Structural biology. - 2059-7983. ; 78:Pt 11, s. 1384-1398
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Tidskriftsartikel (refereegranskat)abstract
- This study describes the structure of DNA polymerase I from Thermus phage G20c, termed PolI_G20c. This is the first structure of a DNA polymerase originating from a group of related thermophilic bacteriophages infecting Thermus thermophilus, including phages G20c, TSP4, P74-26, P23-45 and phiFA and the novel phage Tth15-6. Sequence and structural analysis of PolI_G20c revealed a 3'-5' exonuclease domain and a DNA polymerase domain, and activity screening confirmed that both domains were functional. No functional 5'-3' exonuclease domain was present. Structural analysis also revealed a novel specific structure motif, here termed SβαR, that was not previously identified in any polymerase belonging to the DNA polymerases I (or the DNA polymerase A family). The SβαR motif did not show any homology to the sequences or structures of known DNA polymerases. The exception was the sequence conservation of the residues in this motif in putative DNA polymerases encoded in the genomes of a group of thermophilic phages related to Thermus phage G20c. The structure of PolI_G20c was determined with the aid of another structure that was determined in parallel and was used as a model for molecular replacement. This other structure was of a 3'-5' exonuclease termed ExnV1. The cloned and expressed gene encoding ExnV1 was isolated from a thermophilic virus metagenome that was collected from several hot springs in Iceland. The structure of ExnV1, which contains the novel SβαR motif, was first determined to 2.19 Å resolution. With these data at hand, the structure of PolI_G20c was determined to 2.97 Å resolution. The structures of PolI_G20c and ExnV1 are most similar to those of the Klenow fragment of DNA polymerase I (PDB entry 2kzz) from Escherichia coli, DNA polymerase I from Geobacillus stearothermophilus (PDB entry 1knc) and Taq polymerase (PDB entry 1bgx) from Thermus aquaticus.
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| 50. |
- Allahgholi, Leila, et al.
(författare)
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Exploring a novel β-1,3-glucanosyltransglycosylase, MlGH17B, from a marine Muricauda lutaonensis strain for modification of laminari-oligosaccharides
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Ingår i: Glycobiology. - 1460-2423.
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Tidskriftsartikel (refereegranskat)abstract
- The marine environment, contains plentiful renewable resources, e.g. macroalgae with unique polysaccharides, motivating search for enzymes from marine microorganisms to explore conversion possibilities of the polysaccharides. In this study, the first GH17 glucanosyltransglycosylase, MlGH17B, from a marine bacterium (Muricauda lutaonensis), was characterized. The enzyme was moderately thermostable with Tm at 64.4 °C and 73.2 °C, but an activity optimum at 20 °C, indicating temperature sensitive active site interactions. MlGH17B uses β-1,3 laminari-oligosaccharides with a degree of polymerization (DP) of 4 or higher as donors. Two glucose moieties (bound in the aglycone +1 and + 2 subsites) are cleaved off from the reducing end of the donor while the remaining part (bound in the glycone subsites) is transferred to an incoming β-1,3 glucan acceptor, making a β-1,6-linkage, thereby synthesizing branched or kinked oligosaccharides. Synthesized oligosaccharides up to DP26 were detected by mass spectrometry analysis, showing that repeated transfer reactions occurred, resulting in several β-1,6-linked branches. The modelled structure revealed an active site comprising five subsites: three glycone (-3, -2 and - 1) and two aglycone (+1 and + 2) subsites, with significant conservation of substrate interactions compared to the only crystallized 1,3-β-glucanosyltransferase from GH17 (RmBgt17A from the compost thriving fungus Rhizomucor miehei), suggesting a common catalytic mechanism, despite different phylogenetic origin, growth environment, and natural substrate. Both enzymes lacked the subdomain extending the aglycone subsites, found in GH17 endo-β-glucanases from plants, but this extension was also missing in bacterial endoglucanases (modelled here), showing that this feature does not distinguish transglycosylation from hydrolysis, but may rather relate to phylogeny.
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