| 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. |
- Xie, Sisi, et al.
(författare)
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Dietary ketone body-escalated histone acetylation in megakaryocytes alleviates chemotherapy-induced thrombocytopenia
- 2022
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Ingår i: Science Translational Medicine. - : AMER ASSOC ADVANCEMENT SCIENCE. - 1946-6234 .- 1946-6242. ; 14:673
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Tidskriftsartikel (refereegranskat)abstract
- Chemotherapy-induced thrombocytopenia (CIT) is a severe complication in patients with cancer that can lead to impaired therapeutic outcome and survival. Clinically, therapeutic options for CIT are limited by severe adverse effects and high economic burdens. Here, we demonstrate that ketogenic diets alleviate CIT in both animals and humans without causing thrombocytosis. Mechanistically, ketogenic diet-induced circulating beta-hydroxybutyrate (beta-OHB) increased histone H3 acetylation in bone marrow megakaryocytes. Gain- and loss-of-function experiments revealed a distinct role of 3-beta-hydroxybutyrate dehydrogenase (BDH)-mediated ketone body metabolism in promoting histone acetylation, which promoted the transcription of platelet biogenesis genes and induced thrombocytopoiesis. Genetic depletion of the megakaryocyte-specific ketone body transporter monocarboxylate transporter 1 (MCT1) or pharmacological targeting of MCT1 blocked beta-OHB-induced thrombocytopoiesis in mice. A ketogenesis-promoting diet alleviated CIT in mouse models. Moreover, a ketogenic diet modestly increased platelet counts without causing thrombocytosis in healthy volunteers, and a ketogenic lifestyle inversely correlated with CIT in patients with cancer. Together, we provide mechanistic insights into a ketone body-MCT1-BDH-histone acetylation-platelet biogenesis axis in megakaryocytes and propose a non-toxic, low-cost dietary intervention for combating CIT.
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| 3. |
- Huang, Kun, et al.
(författare)
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Enhanced peak growth of global vegetation and its key mechanisms
- 2018
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Ingår i: Nature Ecology and Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 2:12, s. 1897-1905
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Tidskriftsartikel (refereegranskat)abstract
- The annual peak growth of vegetation is critical in characterizing the capacity of terrestrial ecosystem productivity and shaping the seasonality of atmospheric CO2 concentrations. The recent greening of global lands suggests an increasing trend of terrestrial vegetation growth, but whether or not the peak growth has been globally enhanced still remains unclear. Here, we use two global datasets of gross primary productivity (GPP) and a satellite-derived Normalized Difference Vegetation Index (NDVI) to characterize recent changes in annual peak vegetation growth (that is, GPPmax and NDVImax). We demonstrate that the peak in the growth of global vegetation has been linearly increasing during the past three decades. About 65% of the NDVImax variation is evenly explained by expanding croplands (21%), rising CO2 (22%) and intensifying nitrogen deposition (22%). The contribution of expanding croplands to the peak growth trend is substantiated by measurements from eddy-flux towers, sun-induced chlorophyll fluorescence and a global database of plant traits, all of which demonstrate that croplands have a higher photosynthetic capacity than other vegetation types. The large contribution of CO2 is also supported by a meta-analysis of 466 manipulative experiments and 15 terrestrial biosphere models. Furthermore, we show that the contribution of GPPmax to the change in annual GPP is less in the tropics than in other regions. These multiple lines of evidence reveal an increasing trend in the peak growth of global vegetation. The findings highlight the important roles of agricultural intensification and atmospheric changes in reshaping the seasonality of global vegetation growth.
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| 4. |
- Ke, Wenfan, et al.
(författare)
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Genes in human obesity loci are causal obesity genes in C. elegans
- 2021
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 17:9
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Tidskriftsartikel (refereegranskat)abstract
- Obesity and its associated metabolic syndrome are a leading cause of morbidity and mortality in the United States. Given the disease's heavy burden on patients and the healthcare system, there has been increased interest in identifying pharmacological targets for the treatment and prevention of obesity. Towards this end, genome-wide association studies (GWAS) have identified hundreds of human genetic variants associated with obesity. The next challenge is to experimentally define which of these variants are causally linked to obesity, and could therefore become targets for the treatment or prevention of obesity. Here we employ high-throughput in vivo RNAi screening to test for causality 293 C. elegans orthologs of human obesity-candidate genes reported in GWAS. We RNAi screened these 293 genes in C. elegans subject to two different feeding regimens: (1) regular diet, and (2) high-fructose diet, which we developed and present here as an invertebrate model of diet-induced obesity (DIO). We report 14 genes that promote obesity and 3 genes that prevent DIO when silenced in C. elegans. Further, we show that knock-down of the 3 DIO genes not only prevents excessive fat accumulation in primary and ectopic fat depots but also improves the health and extends the lifespan of C. elegans overconsuming fructose. Importantly, the direction of the association between expression variants in these loci and obesity in mice and humans matches the phenotypic outcome of the loss-of-function of the C. elegans ortholog genes, supporting the notion that some of these genes would be causally linked to obesity across phylogeny. Therefore, in addition to defining causality for several genes so far merely correlated with obesity, this study demonstrates the value of model systems compatible with in vivo high-throughput genetic screening to causally link GWAS gene candidates to human diseases. Author summary Human GWAS have identified hundreds of genetic variants associated with human obesity. The genes being regulated by these variants at the protein or expression level represent potential anti-obesity targets. However, for the vast majority of these genes, it is unclear whether they cause obesity or are coincidentally associated with the disease. Here we use a high-throughput genetic screening strategy to test in vivo in Caenorhabditis elegans the potential causal role of human-obesity GWAS hits. Further, we combined the results of the genetic screen with analyses of mouse and human GWAS databases. As a result, we present 17 genes that promote or prevent C. elegans obesity, and the early onset of organismal deterioration and death associated with obesity. Further, the sign of the correlation between the expression levels of the human genes and their associated clinical traits matches, for the most part, the phenotypic effects of knocking down these genes in C. elegans, suggesting conserved causality and pharmacological potential for these genes.
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| 5. |
- Yang, Hui, et al.
(författare)
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Improving Electrical Performance of Few-Layer MoS2 FETs via Microwave Annealing
- 2019
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 40:7, s. 1116-1119
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Tidskriftsartikel (refereegranskat)abstract
- A few-layer molybdenum disulfide (MoS2) has attracted great attention because of its novel electrical and optoelectrical properties for devices. In this letter, we perform a systematic study on the evolution of the electrical performance of the few-layer MoS2 field-effect transistors (FETs) under microwave annealing. As a result, obvious improvements on electrical properties are achieved for the sample annealed in N-2 ambience between 420 and 840 W. The on/off current ratio of similar to 8.34 x 10(8) and the hysteresis of 2.1 V, which are similar to 150 times higher and similar to 2.1 times smaller compared with that of fabricated MoS2 FET, respectively. The proposed technique provides a new method to approach high-performance few-layer MoS2 FETs with minimized parasitic resistances.
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| 6. |
- Zhao, Jie, et al.
(författare)
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Microstructure-tunable highly conductive graphene-metal composites achieved by inkjet printing and low temperature annealing
- 2018
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP PUBLISHING LTD. - 0960-1317 .- 1361-6439. ; 28:3
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Tidskriftsartikel (refereegranskat)abstract
- We present a method for fabricating highly conductive graphene-silver composite films with a tunable microstructure achieved by means of an inkjet printing process and low temperature annealing. This is implemented by starting from an aqueous ink formulation using a reactive silver solution mixed with graphene nanoplatelets (GNPs), followed by inkjet printing deposition and annealing at 100 degrees C for silver formation. Due to the hydrophilic surfaces and the aid of a polymer stabilizer in an aqueous solution, the GNPs are uniformly covered with a silver layer. Simply by adjusting the content of GNPs in the inks, highly conductive GNP/Ag composites (> 106 S m(-1)), with their microstructure changed from a large-area porous network to a compact film, is formed. In addition, the printed composite films show superior quality on a variety of unconventional substrates compared to its counterpart without GNPs. The availability of composite films paves the way to the metallization in different printed devices, e.g. interconnects in printed circuits and electrodes in energy storage devices.
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