| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Bergström Lind, Sara, et al.
(författare)
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Immunoaffinity Enrichments Followed by Mass Spectrometric Detection for Studying Global Protein Tyrosine Phosphorylation
- 2008
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 7:7, s. 2897-2910
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorylation of protein tyrosine residues regulates important cell functions and is, when dysregulated, often crucially involved in oncogenesis. It is therefore important to develop and evaluate methods for identifying and studying tyrosine phosphorylated (P-Tyr) proteins. P-Tyr proteins are present at very low concentrations within cells, requiring highly selective enrichment methods to be detected. In this study, we applied immunoaffinity as enrichment step for P-Tyr proteins. Five selected anti-phosphotyrosine antibodies (monoclonal antibodies 4G10, PY100, PYKD1, 13F9 and one polyclonal antiserum) were evaluated with respect to their capability to enrich P-Tyr proteins from cell extracts of the K562 leukemia cell line. The enrichment resulted in the detection of a group of proteins that potentially were tyrosine-phosphorylated (putative P-Tyr proteins). High accuracy identification of actual P-Tyr sites were performed using a highly selective and sensitive liquid chromatography Fourier transform mass spectrometer (LC-FTMS) setup with complementary collision activated dissociation (CAD) and electron capture dissociation (ECD) fragmentations. 4G10 and PY100 antibodies recognized the greatest number of putative P-Tyr proteins in initial screening experiments and were therefore further evaluated and compared in immunoaffinity enrichment of both P-Tyr proteins and peptides. Using the 4G10 antibody for enrichment of proteins, we identified 459 putative P-Tyr proteins by MS. Out of these proteins, 12 were directly verified as P-Tyr proteins by MS analysis of the actual site. Using the PY100 antibody for enrichment of peptides, we detected 67 P-Tyr peptides (sites) and 89 putative P-Tyr proteins. Generally, enrichment at the peptide level made it difficult to reliably determine the identity of the proteins. In contrast, protein identification following immunoaffinity enrichment at the protein level gave greater sequence coverage and thus a higher confidence in the protein identification. By combining all available information, 40 proteins were identified as true P-Tyr proteins from the K562 cell line. In conclusion, this study showed that a combination of immunoaffinity enrichment using multiple antibodies of both intact and digested proteins in parallel experiments is required for best possible coverage of all possible P-Tyr proteins in a sample.
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| 3. |
- Eklund, Lina, et al.
(författare)
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Societal drought vulnerability and the Syrian climate-conflict nexus are better explained by agriculture than meteorology
- 2022
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Ingår i: Nature Communications Earth & Environment. - 2662-4435. ; 3:85
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Tidskriftsartikel (refereegranskat)abstract
- Droughts are often suspected to increase the risk of violent conflict through agricultural production shocks, and existing studies often explore these links through meteorological proxies. In Syria, an alleged agricultural collapse caused by drought is assumed to have contributed to increased migration and the conflict outbreak in 2011. Here we use satellite derived cropland and climate data to study land use dynamics in relation to drought and conflict in Syria. We show that claims of an agricultural collapse cannot be substantiated as croplands saw a fast recovery after the 2007–2009 drought. Our study highlights the importance of considering land-use dynamics for understanding linkages between meteorological droughts, agricultural impacts, migration and conflict. Furthermore, our results suggest that the influential drought-migration-conflict narrative for Syria needs to be reexamined, with implications for wider discussions of how climate change might alter conflict risk.
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| 4. |
- Malekkhaiat Häffner, Sara, et al.
(författare)
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Interaction of Laponite with Membrane Components - Consequences for Bacterial Aggregation and Infection Confinement
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 11:17, s. 15389-15400
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Tidskriftsartikel (refereegranskat)abstract
- The antimicrobial effects of Laponite nanoparticles with or without loading of the antimicrobial peptide LL-37 was investigated along with their membrane interactions. The study combines data from ellipsometry, circular dichroism, fluorescence spectroscopy, particle size/ζ potential measurements, and confocal microscopy. As a result of the net negative charge of Laponite, loading of net positively charged LL-37 increases with increasing pH. The peptide was found to bind primarily to the outer surface of the Laponite nanoparticles in a predominantly helical conformation, leading to charge reversal. Despite their net positive charge, peptide-loaded Laponite nanoparticles did not kill Gram-negative Escherichia coli bacteria or disrupt anionic model liposomes. They did however cause bacteria flocculation, originating from the interaction of Laponite and bacterial lipopolysaccharide (LPS). Free LL-37, in contrast, is potently antimicrobial through membrane disruption but does not induce bacterial aggregation in the concentration range investigated. Through LL-37 loading of Laponite nanoparticles, the combined effects of bacterial flocculation and membrane lysis are observed. However, bacteria aggregation seems to be limited to Gram-negative bacteria as Laponite did not cause flocculation of Gram-positive Bacillus subtilis bacteria nor did it bind to lipoteichoic acid from bacterial envelopes. Taken together, the present investigation reports several novel phenomena by demonstrating that nanoparticle charge does not invariably control membrane destabilization and by identifying the ability of anionic Laponite nanoparticles to effectively flocculate Gram-negative bacteria through LPS binding. As demonstrated in cell experiments, such aggregation results in diminished LPS-induced cell activation, thus outlining a promising approach for confinement of infection and inflammation caused by such pathogens.
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| 5. |
- McMahon, Colin J, et al.
(författare)
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Adult congenital heart disease training in Europe: current status, disparities and potential solutions.
- 2023
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Ingår i: Open heart. - 2053-3624. ; 10:2
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to determine the status of training of adult congenital heart disease (ACHD) cardiologists in Europe.A questionnaire was sent to ACHD cardiologists from 34 European countries.Representatives from 31 of 34 countries (91%) responded. ACHD cardiology was recognised by the respective ministry of Health in two countries (7%) as a subspecialty. Two countries (7%) have formally recognised ACHD training programmes, 15 (48%) have informal (neither accredited nor certified) training and 14 (45%) have very limited or no programme. Twenty-five countries (81%) described training ACHD doctors 'on the job'. The median number of ACHD centres per country was 4 (range 0-28), median number of ACHD surgical centres was 3 (0-26) and the median number of ACHD training centres was 2 (range 0-28). An established exit examination in ACHD was conducted in only one country (3%) and formal certification provided by two countries (7%). ACHD cardiologist number versus gross domestic product Pearson correlation coefficient=0.789 (p<0.001).Formal or accredited training in ACHD is rare among European countries. Many countries have very limited or no training and resort to 'train people on the job'. Few countries provide either an exit examination or certification. Efforts to harmonise training and establish standards in exit examination and certification may improve training and consequently promote the alignment of high-quality patient care.
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| 6. |
- Potapov, Anton M., et al.
(författare)
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Global fine-resolution data on springtail abundance and community structure
- 2024
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Ingår i: Scientific Data. - : Nature Publishing Group. - 2052-4463. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Springtails (Collembola) inhabit soils from the Arctic to the Antarctic and comprise an estimated ~32% of all terrestrial arthropods on Earth. Here, we present a global, spatially-explicit database on springtail communities that includes 249,912 occurrences from 44,999 samples and 2,990 sites. These data are mainly raw sample-level records at the species level collected predominantly from private archives of the authors that were quality-controlled and taxonomically-standardised. Despite covering all continents, most of the sample-level data come from the European continent (82.5% of all samples) and represent four habitats: woodlands (57.4%), grasslands (14.0%), agrosystems (13.7%) and scrublands (9.0%). We included sampling by soil layers, and across seasons and years, representing temporal and spatial within-site variation in springtail communities. We also provided data use and sharing guidelines and R code to facilitate the use of the database by other researchers. This data paper describes a static version of the database at the publication date, but the database will be further expanded to include underrepresented regions and linked with trait data.
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| 7. |
- Rasmussen, Claus, et al.
(författare)
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Evaluating competition for forage plants between honey bees and wild bees in Denmark
- 2021
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:4
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Tidskriftsartikel (refereegranskat)abstract
- A recurrent concern in nature conservation is the potential competition for forage plants between wild bees and managed honey bees. Specifically, that the highly sophisticated system of recruitment and large perennial colonies of honey bees quickly exhaust forage resources leading to the local extirpation of wild bees. However, different species of bees show different preferences for forage plants. We here summarize known forage plants for honey bees and wild bee species at national scale in Denmark. Our focus is on floral resources shared by honey bees and wild bees, with an emphasis on both threatened wild bee species and foraging specialist species. Across all 292 known bee species from Denmark, a total of 410 plant genera were recorded as forage plants. These included 294 plant genera visited by honey bees and 292 plant genera visited by different species of wild bees. Honey bees and wild bees share 176 plant genera in Denmark. Comparing the pairwise niche overlap for individual bee species, no significant relationship was found between their overlap and forage specialization or conservation status. Network analysis of the bee-plant interactions placed honey bees aside from most other bee species, specifically the module containing the honey bee had fewer links to any other modules, while the remaining modules were more highly inter-connected. Despite the lack of predictive relationship from the pairwise niche overlap, data for individual species could be summarized. Consequently, we have identified a set of operational parameters that, based on a high foraging overlap (>70%) and unfavorable conservation status (Vulnerable+Endangered+Critically Endangered), can guide both conservation actions and land management decisions in proximity to known or suspected populations of these species.
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| 8. |
- Sjöberg, Lina, 1973-
(författare)
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Genesis och Jernet : ett möte mellan Sara Lidmans Jernbaneepos och bibelns berättelser
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The subject of this dissertation is intertextuality between the Hebrew Bible and a piece of twentieth century Swedish fiction. The main purpose is to create analytical tools and to find a way to deal with fragmentary intertextuality between bible and literature. The material dealt with is a modern suite of novels, Jernbarneeposet (“The Railroad Epic”) by Sara Lidman, on the one hand, and the stories about Abraham, Sarah and Hagar in Genesis 16 and 21 on the other. I suggest a model for analyzing fragmentary references, arguing that the process of interpretation becomes more transparent, and thus more open to critical discussion, if the interpreter deals with each separate reference on three levels – “marker”, “means” and “effect”. It is assumed that the reader of fragmentary intertextuality becomes engaged in a number of small hermeneutical operations. The purpose of systematization is to organize and articulate each step in such an operation. The second half of the dissertation takes its point of departure from an observation that the failure to interpret the significance of the personal relationships indicated in several Genesis stories is common to both traditional and postmodern biblical scholarship. Therefore, I investigate the possibility of using modern literary fiction as a tool in interpreting the emotional aspects of the Abraham, Sarah and Hagar stories. I propose that it is possible to make use of modern literary works in biblical scholarship, not as commentaries, but as inspiration. The question discussed is: How then, can this inspiration be integrated in serious biblical scholarship?
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| 9. |
- Thanabalasingham, Gaya, et al.
(författare)
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Mutations in HNF1A Result in Marked Alterations of Plasma Glycan Profile
- 2013
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 62:4, s. 1329-1337
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Tidskriftsartikel (refereegranskat)abstract
- A recent genome-wide association study identified hepatocyte nuclear factor 1-alpha (HNF1A) as a key regulator of fucosylation. We hypothesized that loss-of-function HNF1A mutations causal for maturity-onset diabetes of the young (MOD?) would display altered fucosylation of N-linked glycans on plasma proteins and that glycan biomarkers could improve the efficiency of a diagnosis of HNF1A-MODY. In a pilot comparison of 33 subjects with HNF1A-MODY and 41 subjects with type 2 diabetes, 15 of 29 glycan measurements differed between the two groups. The DG9-glycan index, which is the ratio of fucosylated to nonfucosylated triantennary glycans, provided optimum discrimination in the pilot study and was examined further among additional subjects with HNF1A-MODY (n = 188), glucokinase (GCE)-MODY (n = 118), hepatocyte nuclear factor 4-alpha (HNF4A)-MODY (n = 40), type 1 diabetes (n = 98), type 2 diabetes (n = 167), and nondiabetic controls (n = 98). The DG9-glycan index was markedly lower in HNF1A-MODY than in controls or other diabetes subtypes, offered good discrimination between HNF1A-MODY and both type 1 and type 2 diabetes (C statistic >= 0.90), and enabled us to detect three previously undetected HNF1A mutations in patients with diabetes. In conclusion, glycan profiles are altered substantially in HNF1A-MODY, and the DG9-glycan index has potential clinical value as a diagnostic biomarker of HNF1A dysfunction.
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| 10. |
- Weischenfeldt, Joachim, et al.
(författare)
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NMD is essential for hematopoietic stem and progenitor cells and for eliminating by-products of programmed DNA rearrangements
- 2008
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Ingår i: Genes & Development. - : Cold Spring Harbor Laboratory. - 1549-5477 .- 0890-9369. ; 22:10, s. 1381-1396
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Tidskriftsartikel (refereegranskat)abstract
- Nonsense-mediated mRNA decay (NMD) is a post-transcriptional surveillance process that eliminates mRNAs containing premature termination codons (PTCs). NMD has been hypothesized to impact on several aspects of cellular function; however, its importance in the context of a mammalian organism has not been addressed in detail. Here we use mouse genetics to demonstrate that hematopoietic-specific deletion of Upf2, a core NMD factor, led to the rapid, complete, and lasting cell-autonomous extinction of all hematopoietic stem and progenitor populations. In contrast, more differentiated cells were only mildly affected in Upf2-null mice, suggesting that NMD is mainly essential for proliferating cells. Furthermore, we show that UPF2 loss resulted in the accumulation of nonproductive rearrangement by-products from the Tcrb locus and that this, as opposed to the general loss of NMD, was particularly detrimental to developing T-cells. At the molecular level, gene expression analysis showed that Upf2 deletion led to a profound skewing toward up-regulated mRNAs, highly enriched in transcripts derived from processed pseudogenes, and that NMD impacts on regulated alternative splicing events. Collectively, our data demonstrate a unique requirement of NMD for organismal survival.
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