| 1. |
- A. Strumpfer, Johan, et al.
(författare)
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Stretching of Twitchin Kinase
- 2012
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Ingår i: Biophysical Journal. - St. Louis, MO, United States : Cell Press. - 0006-3495 .- 1542-0086. ; 102:3 Supplement 1, s. 361a-362a
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Tidskriftsartikel (refereegranskat)abstract
- The giant proteins from the titin family, that form cytoskeletal filaments, have emerged as key mechanotransducers in the sarcomere. These proteins contain a conserved kinase region, which is auto-inhibited by a C-terminal tail domain. The inhibitory tail domain occludes the active sites of the kinases, thus preventing ATP from binding. It was proposed that through application of a force, such as that arising during muscle contraction, the inhibitory tail becomes detached, lifting inhibition. The force-sensing ability of titin kinase was demonstrated in AFM experiments and simulations [Puchner, et al., 2008, PNAS:105, 13385], which showed indeed that mechanical forces can remove the autoinhibitory tail of titin kinase. We report here steered molecular dynamics simulations (SMD) of the very recently resolved crystal structure of twitchin kinase, containing the kinase region and flanking fibronectin and immuniglobulin domains, that show a variant mechanism. Despite the significant structural and sequence similarity to titin kinase, the autoinhibitory tail of twitchin kinase remains in place upon stretching, while the N-terminal lobe of the kinase unfolds. The SMD simulations also show that the detachment and stretching of the linker between fibronectin and kinase regions, and the partial extension of the autoinhibitory tail, are the primary force-response. We postulate that this stretched state, where all structural elements are still intact, may represent the physiologically active state.
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| 2. |
- Chan, Sherwin, et al.
(författare)
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Regulation of PfEMP1-VAR2CSA translation by a Plasmodium translation-enhancing factor
- 2017
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Ingår i: Nature Microbiology. - : Springer Science and Business Media LLC. - 2058-5276. ; 2:7
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Tidskriftsartikel (refereegranskat)abstract
- Pregnancy-associated malaria commonly involves the binding of Plasmodium falciparum-infected erythrocytes to placental chondroitin sulfate A (CSA) through the PfEMP1-VAR2CSA protein. VAR2CSA is translationally repressed by an upstream open reading frame. In this study, we report that the P. falciparum translation enhancing factor (PTEF) relieves upstream open reading frame repression and thereby facilitates VAR2CSA translation. VAR2CSA protein levels in var2csa-transcribing parasites are dependent on the expression level of PTEF, and the alleviation of upstream open reading frame repression requires the proteolytic processing of PTEF by PfCalpain. Cleavage generates a C-terminal domain that contains a sterile-alpha-motif-like domain. The C-terminal domain is permissive to cytoplasmic shuttling and interacts with ribosomes to facilitate translational derepression of the var2csa coding sequence. It also enhances translation in a heterologous translation system and thus represents the first non-canonical translation enhancing factor to be found in a protozoan. Our results implicate PTEF in regulating placental CSA binding of infected erythrocytes.
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| 3. |
- D’Amico, Michele, et al.
(författare)
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Ectomycorrhizal utilization of different phosphorus sources in a glacier forefront in the Italian Alps
- 2020
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 446:1-2, s. 81-95
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Tidskriftsartikel (refereegranskat)abstract
- Aims: In deglaciated surfaces, lithology influences habitat development. In particular, serpentinite inhibits soil evolution and plant colonization because of insufficient phosphorus (P) content, among other stressful properties. In nutrient-poor environments, ectomycorrhizal fungi (EMF) play a key role exploring the soil for P beyond the rhizosphere. In this study, we followed the role of EMF in accessing inorganic and organic P along two proglacial soil chronosequences in the Alps (NW Italy), respectively characterized by pure serpentinite till and serpentinite mixed with 10% of gneiss, and colonized by European Larch. Methods: The access to inorganic and organic P forms by EMF was studied using specific mesh-bags for fungal hyphae entry, filled with quartz sand and inorganic phosphate (Pi) or myo-inositolhexaphosphate (InsP6) adsorbed onto goethite. They were incubated over 13 months at the organic/mineral horizon interface. After harvesting, EMF colonization via ergosterol analysis and the amount of P and Fe removed from mesh bags were measured. Results: Ergosterol increased along the two chronosequences with slightly greater values on serpentinite and in Pi-containing bags. Up to 65% of Pi was removed from mesh-bags, only partly accompanied by a parallel release of Fe. The amount of InsP6 released was instead less than 45% and mostly removed with goethite. Conclusions: The results suggest that, in extremely P-poor environments, EMF are able to release both inorganic and organic P forms from highly stabilized associations.
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| 4. |
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| 5. |
- Lai, Ian-Lin, et al.
(författare)
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Gas outflow and dust transport of comet 67P/Churyumov-Gerasimenko
- 2016
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 462, s. S533-S546
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Tidskriftsartikel (refereegranskat)abstract
- Because of the diurnal thermal cycle and the irregular shape of the nucleus, gas outflow of comet 67P/Churyumov-Gerasimenko could be highly anisotropic as indicated by the colliminated dust jet structures on the sunlit side. Based on the OSIRIS imaging observations of the outgassing effect, a simple model of surface sublimation can be constructed by taking into account the dependence on the solar insolation. With preliminary information on the time variability of the global gas production rate, a sequence of gas coma models can be generated at different epochs before and after perihelion. We also investigate different patterns of dust particle dynamics under the influences of nuclear rotation and gas drag. From these considerations, a consistent picture of the spatial distribution of dusty materials across the surface of comet 67P as it moves around the perihelion can be developed. It is found that because of the redeposition of the ejected dust from the Southern hemisphere to the Northern hemisphere during the southern summer season the Hapi region could gain up to 0.4 m while the Wosret region would lose up to 1.8 m of dust mantle per orbit.
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| 6. |
- Lee, Jui-Chi, et al.
(författare)
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Geomorphological mapping of comet 67P/Churyumov-Gerasimenko's Southern hemisphere
- 2016
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 462, s. S573-S592
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Tidskriftsartikel (refereegranskat)abstract
- In 2015 May, the Southern hemisphere of comet 67P/Churyumov-Gerasimenko became visible by the OSIRIS cameras on-board the Rosetta spacecraft. The resolution was high enough to carry out a detailed analysis of the surface morphology, which is quite different from the Northern hemisphere. Previous works show that fine particle deposits are the most extensive geological unit in the Northern hemisphere. In contrast, the Southern hemisphere is dominated by outcropping consolidated terrain. In this work, we provide geomorphological maps of the Southern hemisphere with the distinction of both geological units and linear features. The geomorphological maps described in this study allow us to gain a better understanding of the processes shaping the comet nucleus and the distribution of primary structures such as fractures and strata.
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| 7. |
- Maastrup, Ragnhild, et al.
(författare)
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Compliance with the Baby-friendly Hospital Initiative for Neonatal Wards (Neo-BFHI) : A cross-sectional study in 36 countries
- 2019
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Ingår i: Maternal and Child Nutrition. - : Blackwell Science Ltd.. - 1740-8695 .- 1740-8709. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- In 2012, the Baby-friendly Hospital Initiative for Neonatal Wards (Neo-BFHI) began providing recommendations to improve breastfeeding support for preterm and ill infants. This cross-sectional survey aimed to measure compliance on a global level with the Neo-BFHI’s expanded Ten steps to Successful Breastfeeding and three Guiding Principles in neonatal wards. In 2017 the Neo-BFHI Self-Assessment questionnaire was used in 15 languages to collect data from neonatal wards of all levels of care. Answers were summarized into compliance scores ranging from 0 to 100 at the ward, country and international levels. A total of 917 neonatal wards from 36 low, middle and high-income countries from all continents participated. The median international overall score was 77, and median country overall scores ranged from 52 to 91. Guiding Principle 1 (respect for mothers), Step 5 (breastfeeding initiation and support), and Step 6 (human milk use) had the highest scores, 100, 88, and 88, respectively. Steps 3 (antenatal information) and 7 (rooming-in) had the lowest scores, 63 and 67, respectively. High-income countries had significantly higher scores for Guiding principle 2 (family-centered care), Step 4 (skin-to-skin contact) and Step 5. Neonatal wards in hospitals ever-designated Baby-friendly had significantly higher scores than those never designated. Sixty percent of managers stated they would like to obtain Neo-BFHI designation. Currently, Neo-BFHI recommendations are partly implemented in many countries. The high number of participating wards indicates international readiness to expand Baby-friendly standards to neonatal settings. Hospitals and governments should increase their efforts to better support breastfeeding in neonatal wards.
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| 8. |
- Massironi, Matteo, et al.
(författare)
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Two independent and primitive envelopes of the bilobate nucleus of comet 67P
- 2015
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 526:7573, s. 402-405
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Tidskriftsartikel (refereegranskat)abstract
- The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary(1,2) and primordial processes(3,4). The peculiar bilobed shape of comet 67P/Churyumov-Gerasimenko may be the result of the fusion of two objects that were once separate or the result of a localized excavation by outgassing at the interface between the two lobes(5). Here we report that the comet's major lobe is enveloped by a nearly continuous set of strata, up to 650 metres thick, which are independent of an analogous stratified envelope on the minor lobe. Gravity vectors computed for the two lobes separately are closer to perpendicular to the strata than those calculated for the entire nucleus and adjacent to the neck separating the two lobes. Therefore comet 67P/Churyumov-Gerasimenko is an accreted body of two distinct objects with 'onion-like' stratification, which formed before they merged. We conclude that gentle, low-velocity collisions occurred between two fully formed kilometre-sized cometesimals in the early stages of the Solar System. The notable structural similarities between the two lobes of comet 67P/Churyumov-Gerasimenko indicate that the early-forming cometesimals experienced similar primordial stratified accretion, even though they formed independently.
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| 9. |
- Moor, Kathrin, et al.
(författare)
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High-avidity IgA protects the intestine by enchaining growing bacteria
- 2017
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Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 544:7651, s. 498-
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Tidskriftsartikel (refereegranskat)abstract
- Vaccine-induced high-avidity IgA can protect against bacterial enteropathogens by directly neutralizing virulence factors or by poorly defined mechanisms that physically impede bacterial interactions with the gut tissues ('immune exclusion')(1-3). IgA-mediated cross-linking clumps bacteria in the gut lumen and is critical for protection against infection by non-typhoidal Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium). However, classical agglutination, which was thought to drive this process, is efficient only at high pathogen densities (>= 10(8) non-motile bacteria per gram). In typical infections, much lower densities(4,5) (10(0)-10(7) colony-forming units per gram) of rapidly dividing bacteria are present in the gut lumen. Here we show that a different physical process drives formation of clumps in vivo: IgA-mediated cross-linking enchains daughter cells, preventing their separation after division, and clumping is therefore dependent on growth. Enchained growth is effective at all realistic pathogen densities, and accelerates pathogen clearance from the gut lumen. Furthermore, IgA enchains plasmid-donor and -recipient clones into separate clumps, impeding conjugative plasmid transfer in vivo. Enchained growth is therefore a mechanism by which IgA can disarm and clear potentially invasive species from the intestinal lumen without requiring high pathogen densities, inflammation or bacterial killing. Furthermore, our results reveal an untapped potential for oral vaccines in combating the spread of antimicrobial resistance.
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| 10. |
- Pajola, Maurizio, et al.
(författare)
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Aswan site on comet 67P/Churyumov-Gerasimenko : Morphology, boulder evolution, and spectrophotometry
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 592
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We provide a detailed morphological analysis of the Aswan site on comet 67P/Churyumov-Gerasimenko (67P). We derive the size-frequency distribution of boulders >= 2 m and correlate this distribution with the gravitational slopes for the first time on a comet. We perform the spectral analysis of this region to understand if possible surface variegation is related to the different surface textures observable on the different units. Methods. We used two OSIRIS Narrow Angle Camera (NAC) image data sets acquired on September 19 and 22, 2014, with a scale of 0.5 m/px. Gravitational slopes derived from the 3D shape model of 67P were used to identify and interpret the different units of the site. By means of the high-resolution NAC data sets, boulders >= 2.0 m can be unambiguously identified and extracted using the software ArcGIS. Coregistered and photometrically corrected color cubes were used to perform the spectral analyses, and we retrieved the spectral properties of the Aswan units. Results. The high-resolution morphological map of the Aswan site (0.68 km(2)) shows that this site is characterized by four different units: fine-particle deposits located on layered terrains, gravitational accumulation deposits, taluses, and the outcropping layered terrain. Multiple lineaments are identified on the Aswan cliff, such as fractures, exposed layered outcrops, niches, and terraces. Close to the terrace margin, several arched features observed in plan view suggest that the margin progressively retreats as a result of erosion. The size-frequency of boulders >= 2 m in the entire study area has a power-law index of -3.9 +0.2/-0.3 (1499 boulders >= 2 m/km(2)), suggesting that the Aswan site is mainly dominated by gravitational events triggered by sublimation and/or thermal insolation weathering causing regressive erosion. The boulder size-frequency distribution versus gravitational slopes indicates that when higher gravitational slope terrains are considered, only boulders <= 10 m are identified, as well as steeper power-slope indices. In addition, no boulders >= 2 m are observed on slopes >= 50 degrees. This may indicate that larger blocks detached from a sublimating cliff cannot rest at these slopes and consequently fall down. The spectral analysis performed on the site shows that despite different morphologic units, no spectral differences appear in the multiple textures. This may confirm a redistribution of particles across the nucleus as a consequence of airfall, whether coming from Hapi or from the southern hemisphere when it is active during perihelion.
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