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41.
Robert?M. Glaeser Bong-Gyoon Han Roseann Csencsits Alison Killilea Arto Pulk Jamie?H.D. Cate 《Biophysical journal》2016,110(4):749-755
Poor consistency of the ice thickness from one area of a cryo-electron microscope (cryo-EM) specimen grid to another, from one grid to the next, and from one type of specimen to another, motivates a reconsideration of how to best prepare suitably thin specimens. Here we first review the three related topics of wetting, thinning, and stability against dewetting of aqueous films spread over a hydrophilic substrate. We then suggest that the importance of there being a surfactant monolayer at the air-water interface of thin, cryo-EM specimens has been largely underappreciated. In fact, a surfactant layer (of uncontrolled composition and surface pressure) can hardly be avoided during standard cryo-EM specimen preparation. We thus suggest that better control over the composition and properties of the surfactant layer may result in more reliable production of cryo-EM specimens with the desired thickness. 相似文献
42.
A method for in situ monitoring of the isotope composition of tree xylem water using laser spectroscopy 总被引:1,自引:0,他引:1
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Till H. M. Volkmann Kathrin Kühnhammer Barbara Herbstritt Arthur Gessler Markus Weiler 《Plant, cell & environment》2016,39(9):2055-2063
Field studies analyzing the stable isotope composition of xylem water are providing important information on ecosystem water relations. However, the capacity of stable isotopes to characterize the functioning of plants in their environment has not been fully explored because of methodological constraints on the extent and resolution at which samples could be collected and analysed. Here, we introduce an in situ method offering the potential to continuously monitor the stable isotope composition of tree xylem water via its vapour phase using a commercial laser‐based isotope analyser and compact microporous probes installed into the xylem. Our technique enables efficient high‐frequency measurement with intervals of only a few minutes per sample while eliminating the need for costly and cumbersome destructive collection of plant material and laboratory‐based processing. We present field observations of xylem water hydrogen and oxygen isotope compositions obtained over several days including a labelled irrigation event and compare them against results from concurrent destructive sampling with cryogenic distillation and mass spectrometric analysis. The data demonstrate that temporal changes as well as spatial patterns of integration in xylem water isotope composition can be resolved through direct measurement. The new technique can therefore present a valuable tool to study the hydraulic architecture and water utilization of trees. 相似文献
43.
Corinna Seliger Anne-Louise Meyer Kathrin Renner Verena Leidgens Sylvia Moeckel Birgit Jachnik 《Cell cycle (Georgetown, Tex.)》2016,15(13):1755-1766
To this day, glioblastoma (GBM) remains an incurable brain tumor. Previous research has shown that metformin, an oral anti-diabetic drug, may decrease GBM cell proliferation and migration especially in brain tumor initiating cells (BTICs). As transforming growth factor β 2 (TGF-β2) has been reported to promote high-grade glioma and is inhibited by metformin in other tumors, we explored whether metformin directly interferes with TGF-β2-signaling. Functional investigation of proliferation and migration of primary BTICs after treatment with metformin+/?TGF-β2 revealed that metformin doses as low as 0.01 mM metformin thrice a day were able to inhibit proliferation of susceptible cell lines, whereas migration was impacted only at higher doses. Known cellular mechanisms of metformin, such as increased lactate secretion, reduced oxygen consumption and activated AMPK-signaling, could be confirmed. However, TGF-β2 and metformin did not act as functional antagonists, but both rather inhibited proliferation and/or migration, if significant effects were present. We did not observe a relevant influence of metformin on TGF-β2 mRNA expression (qRT-PCR), TGF-β2 protein expression (ELISA) or SMAD-signaling (Western blot). Therefore, it seems that metformin does not exert its inhibitory effects on GBM BTIC proliferation and migration by altering TGF-β2-signaling. Nonetheless, as low doses of metformin are able to reduce proliferation of certain GBM cells, further exploration of predictors of BTICs' susceptibility to metformin appears justified. 相似文献
44.
Annette Masuch Kathrin Budde Gabi Kastenmüller Anna Artati Jerzy Adamski Henry Vlzke Matthias Nauck Maik Pietzner 《Journal of cellular and molecular medicine》2019,23(8):5144-5153
Metabolomics studies now approach large sample sizes and the health characterization of the study population often include complete blood count (CBC) results. Upon careful interpretation the CBC aids diagnosis and provides insight into the health status of the patient within a clinical setting. Uncovering metabolic signatures associated with parameters of the CBC in apparently healthy individuals may facilitate interpretation of metabolomics studies in general and related to diseases. For this purpose 879 subjects from the population‐based Study of Health in Pomerania (SHIP)‐TREND were included. Using metabolomics data resulting from mass‐spectrometry based measurements in plasma samples associations of specific CBC parameters with metabolites were determined by linear regression models. In total, 118 metabolites significantly associated with at least one of the CBC parameters. Strongest associations were observed with metabolites of heme degradation and energy production/consumption. Inverse association seen with mean corpuscular volume and mean corpuscular haemoglobin comprised metabolites potentially related to kidney function. The presently identified metabolic signatures are likely derived from the general function and formation/elimination of blood cells. The wealth of associated metabolites strongly argues to consider CBC in the interpretation of metabolomics studies, in particular if mutual effects on those parameters by the disease of interest are known. 相似文献
45.
Wounding-Induced Stomatal Closure Requires Jasmonate-Mediated Activation of GORK K+ Channels by a Ca2+ Sensor-Kinase CBL1-CIPK5 Complex 总被引:1,自引:0,他引:1
46.
Moritz von Cossel Kathrin Steberl Jens Hartung Lorena A. Pereira Andreas Kiesel Iris Lewandowski 《Global Change Biology Bioenergy》2019,11(11):1376-1391
The cultivation of perennial wild plant mixtures (WPMs) in biogas cropping systems dominated by maize (Zea mays L.) restores numerous ecosystem functions and improves both spatial and temporal agrobiodiversity. In addition, the colorful appearance of WPM can help enhance landscape beauty. However, their methane yield per hectare (MYH) varies greatly and amounts to only about 50% that of maize. This study aimed at decreasing MYH variability and increasing accumulated MYH of WPM by optimizing the establishment method. A field trial was established in southwest Germany in 2014, and is still running. It tested the effects of three WPM establishment procedures (E1: alone [without maize, in May], E2: undersown in cover crop maize [in May], E3: WPM sown after whole‐crop harvest of spring barley [Hordeum vulgare L.] in June) on both MYH and species diversity of two WPMs [S1, S2]). Mono‐cropped maize and cup plant (Silphium perfoliatum L.) were used as reference crops. Of the WPM treatments tested, S2E2 achieved the highest (19,296 , 60.5% of maize) and S1E1 the lowest accumulated MYH (8,156 , 25.6% of maize) in the years 2014–2018. Cup plant yielded slightly higher than S2E2 (19,968 , 62.6% of maize). In 2014, the WPM sown under maize did not significantly affect the cover crop performance. From 2015 onward, E1 and E2 had comparable average annual MYH and average annual number of WPM species. With a similar accumulated MYH but significantly higher number of species (3.5–10.2), WPM S2E2 outperformed cup plant. Overall, the long‐term MYH performance of WPM cultivation for biogas production can be significantly improved by undersowing with maize as cover crop. This improved establishment method could help facilitate the implementation of WPM cultivation for biogas production and thus reduce the trade‐off between bioenergy and biodiversity. 相似文献
47.
Mosquito control actions affect chironomid diversity in temporary wetlands of the Upper Rhine Valley
Kathrin Theissinger Nina Rder Stefanie Allgeier Arne J. Beermann Carsten A. Brühl Anna Friedrich Susanne Michiels Klaus Schwenk 《Molecular ecology》2019,28(18):4300-4316
The Upper Rhine Valley, a “hotspot of biodiversity” in Germany, has been treated with the biocide Bacillus thuringiensis var. israelensis (Bti) for mosquito control for decades. Previous studies discovered Bti nontarget effects in terms of severe chironomid abundance reductions. In this study, we investigated the impact of Bti on species level and addressed the community composition of the nontarget family Chironomidae by use of community metabarcoding. Chironomid emergence data were collected in three mosquito‐control relevant wetland types in the Upper Rhine Valley. For all three sites the chironomid species composition, based on operational taxonomic units (OTUs), was different to varying degrees in the Bti‐treated samples versus control samples, ranging from a significant 63% OTU reduction to an OTU replacement. We assumed that predatory chironomids are less prone to Bti than filter feeders, as the latter feed on floating particles leading to direct ingestion of Bti. However, a comparable percentage of predators and filter feeders (63% and 65%, respectively) was reduced in the Bti samples, suggesting that the feeding strategy is not the main driver for Bti sensitivity in chironomids. Finally, our data was compared to a three‐year‐old data set, indicating possible chironomid community recovery due to species recolonization a few years after the last Bti application. Considering the currently discussed worldwide insect decline we recommend a rethinking of the usage of the biocide Bti, and to prevent its ongoing application especially in nature protection reserves to enhance ecological resilience and to prevent boosting the current biodiversity loss. 相似文献
48.
Markus Oberpaul Stephan Brinkmann Michael Marner Sanja Mihajlovic Benedikt Leis Maria A. Patras Christoph Hartwig Andreas Vilcinskas Peter E. Hammann Till F. Schäberle Marius Spohn Jens Glaeser 《Microbial biotechnology》2022,15(2):415-430
High-throughput platforms facilitating screening campaigns of environmental samples are needed to discover new products of natural origin counteracting the spreading of antimicrobial resistances constantly threatening human and agricultural health. We applied a combination of droplet microfluidics and fluorescence-activated cell sorting (FACS)-based technologies to access and assess a microbial environmental sample. The cultivation performance of our microfluidics workflow was evaluated in respect to the utilized cultivation media by Illumina amplicon sequencing of a pool of millions of droplets, respectively. This enabled the rational selection of a growth medium supporting the isolation of microbial diversity from soil (five phyla affiliated to 57 genera) including a member of the acidobacterial subgroup 1 (genus Edaphobacter). In a second phase, the entire diversity covered by 1071 cultures was used for an arrayed bioprospecting campaign, resulting in > 6000 extracts tested against human pathogens and agricultural pests. After redundancy curation by using a combinatorial chemical and genomic fingerprinting approach, we assigned the causative agents present in the extracts. Utilizing UHPLC-QTOF-MS/MS-guided fractionation and microplate-based screening assays in combination with molecular networking the production of bioactive ionophorous macrotetrolides, phospholipids, the cyclic lipopetides massetolides E, F, H and serratamolide A and many derivatives thereof was shown. 相似文献
49.
Empty class II major histocompatibility complex created by peptide photolysis establishes the role of DM in peptide association 总被引:1,自引:0,他引:1
Grotenbreg GM Nicholson MJ Fowler KD Wilbuer K Octavio L Yang M Chakraborty AK Ploegh HL Wucherpfennig KW 《The Journal of biological chemistry》2007,282(29):21425-21436
DM catalyzes the exchange of peptides bound to Class II major histocompatibility complex (MHC) molecules. Because the dissociation and association components of the overall reaction are difficult to separate, a detailed mechanism of DM catalysis has long resisted elucidation. UV irradiation of DR molecules loaded with a photocleavable peptide (caged Class II MHC molecules) enabled synchronous and verifiable evacuation of the peptide-binding groove and tracking of early binding events in real time by fluorescence polarization. Empty DR molecules generated by photocleavage rapidly bound peptide but quickly resolved into species with substantially slower binding kinetics. DM formed a complex with empty DR molecules that bound peptide with even faster kinetics than empty DR molecules just having lost their peptide cargo. Mathematical models demonstrate that the peptide association rate of DR molecules is substantially higher in the presence of DM. We therefore unequivocally establish that DM contributes directly to peptide association through formation of a peptide-loading complex between DM and empty Class II MHC. This complex rapidly acquires a peptide analogous to the MHC class I peptide-loading complex. 相似文献
50.
Schöneberg T Hermsdorf T Engemaier E Engel K Liebscher I Thor D Zierau K Römpler H Schulz A 《Purinergic signalling》2007,3(4):255-268
Metabotropic pyrimidine and purine nucleotide receptors (P2Y receptors) belong to the superfamily of G protein-coupled receptors
(GPCR). They are distinguishable from adenosine receptors (P1) as they bind adenine and/or uracil nucleotide triphosphates
or diphosphates depending on the subtype. Over the past decade, P2Y receptors have been cloned from a variety of tissues and
species, and as many as eight functional subtypes have been characterized. Most recently, several members of the P2Y12-like receptor group, which includes the clopidogrel-sensitive ADP receptor P2Y12, have been deorphanized. The P2Y12-like receptor group comprises several structurally related GPCR which, however, display heterogeneous agonist specificity
including nucleotides, their derivatives, and lipids. Besides the established function of P2Y12 in platelet activation, expression in macrophages, neuronal and glial cells as well as recent results from functional studies
implicate that several members of this group may have specific functions in neurotransmission, inflammation, chemotaxis, and
response to tissue injury. This review focuses specifically on the structure-function relation and shortly summarizes some
aspects of the physiological relevance of P2Y12-like receptor members. 相似文献