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https://www.readbyqxmd.com/read/28448929/microbial-use-of-low-molecular-weight-dom-in-filtered-and-unfiltered-freshwater-role-of-ultra-small-microorganisms-and-implications-for-water-quality-monitoring
#1
F L Brailsford, H C Glanville, M R Marshall, P N Golyshin, P J Johnes, C A Yates, A T Owen, D L Jones
Dissolved organic matter (DOM) plays a central role in regulating productivity and nutrient cycling in freshwaters. It is therefore vital that we can representatively sample and preserve DOM in freshwaters for subsequent analysis. Here we investigated the effect of filtration, temperature (5 and 25°C) and acidification (HCl) on the persistence of low molecular weight (MW) dissolved organic carbon (DOC), nitrogen (DON) and orthophosphate in oligotrophic and eutrophic freshwater environments. Our results showed the rapid loss of isotopically-labelled glucose and amino acids from both filtered (0...
April 24, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28448054/lipid-droplet-isolation-for-quantitative-mass-spectrometry-analysis
#2
Kathrin Rösch, Marcel Kwiatkowski, Hartmut Schlüter, Eva Herker
Lipid droplets are vital to the replication of a variety of different pathogens, most prominently the Hepatitis C Virus (HCV), as the putative site of virion morphogenesis. Quantitative lipid droplet proteome analysis can be used to identify proteins that localize to or are displaced from lipid droplets under conditions such as virus infections. Here, we describe a protocol that has been successfully used to characterize the changes in the lipid droplet proteome following infection with HCV. We use Stable Isotope Labeling with Amino Acids in Cell Culture (SILAC) and thus label the complete proteome of one population of cells with "heavy" amino acids to quantitate the proteins by mass spectrometry...
April 17, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28447979/reconstitution-of-nucleosomes-with-differentially-isotope-labeled-sister-histones
#3
Stamatios Liokatis
Asymmetrically modified nucleosomes contain the two copies of a histone (sister histones) decorated with distinct sets of Post-translational Modifications (PTMs). They are newly identified species with unknown means of establishment and functional implications. Current analytical methods are inadequate to detect the copy-specific occurrence of PTMs on the nucleosomal sister histones. This protocol presents a biochemical method for the in vitro reconstitution of nucleosomes containing differentially isotope-labeled sister histones...
March 26, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28447675/back-exchange-a-novel-approach-to-quantifying-oxygen-diffusion-and-surface-exchange-in-ambient-atmospheres
#4
Samuel J Cooper, Mathew Niania, Franca Hoffmann, John A Kilner
A novel two-step Isotopic Exchange (IE) technique has been developed to investigate the influence of oxygen containing components of ambient air (such as H2O and CO2) on the effective surface exchange coefficient (k*) of a common mixed ionic electronic conductor material. The two step 'back-exchange' technique was used to introduce a tracer diffusion profile, which was subsequently measured using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The isotopic fraction of oxygen in a dense sample as a function of distance from the surface, before and after the second exchange step, could then be used to determine the surface exchange coefficient in each atmosphere...
April 27, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28447615/millions-of-boreal-shield-lakes-can-be-used-to-probe-archaean-ocean-biogeochemistry
#5
S L Schiff, J M Tsuji, L Wu, J J Venkiteswaran, L A Molot, R J Elgood, M J Paterson, J D Neufeld
Life originated in Archaean oceans, almost 4 billion years ago, in the absence of oxygen and the presence of high dissolved iron concentrations. Early Earth oxidation is marked globally by extensive banded iron formations but the contributing processes and timing remain controversial. Very few aquatic habitats have been discovered that match key physico-chemical parameters of the early Archaean Ocean. All previous whole ecosystem Archaean analogue studies have been confined to rare, low sulfur, and permanently stratified lakes...
April 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28447488/observation-of-the-162-dy-164-dy-isotope-shift-for-the-0-%C3%A2-16%C3%A2-717-79%C3%A2-cm-1-optical-transition
#6
Luiz Felipe Nardin Barreta, Alessandro Rogério Victor, Patrícia Bueno, Jhonatha Ricardo Dos Santos, Carlos Alberto Barbosa da Silveira, José Wilson Neri, Jonas Jakutis Neto, Maria Esther Sbampato, Marcelo Geraldo Destro
In this work, we report a newly observed isotope shift between (162)Dy and (164)Dy isotopes for the 0 → 16 717.79 cm(-1) (598.003 nm) optical transition. We compared the newly observed results against two other lines (597.452 nm and 598.859 nm), which we measured in this work, and were already reported in the literature. The newly observed 162-164 Dy isotope shift, shows at least a 20% larger isotope shift than the isotope shifts for the other two lines investigated. The larger 162-164 isotope shift observed for the 598...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28447482/quantitative-potassium-measurements-with-laser-induced-breakdown-spectroscopy-using-low-energy-lasers-application-to-in-situ-k-ar-geochronology-for-planetary-exploration
#7
Yuichiro Cho, Misa Horiuchi, Kazuo Shibasaki, Shingo Kameda, Seiji Sugita
In situ radiogenic isotope measurements to obtain the absolute age of geologic events on planets are of great scientific value. In particular, K-Ar isochrons are useful because of their relatively high technical readiness and high accuracy. Because this isochron method involves spot-by-spot K measurements using laser-induced breakdown spectroscopy (LIBS) and simultaneous Ar measurements with mass spectrometry, LIBS measurements are conducted under a high vacuum condition in which emission intensity decreases significantly...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28446901/anaerobic-methanotrophic-archaea-of-the-anme-2d-cluster-are-active-in-a-low-sulfate-iron-rich-freshwater-sediment
#8
Hannah S Weber, Kirsten S Habicht, Bo Thamdrup
ANaerobic MEthanotrophic (ANME) archaea remove the greenhouse gas methane from anoxic environments and diminish its flux to the atmosphere. High methane removal efficiencies are well documented in marine environments, whereas anaerobic oxidation of methane (AOM) was only recently indicated as an important methane sink in freshwater systems. Freshwater AOM-mediating microorganisms lack taxonomic identification and only little is known about metabolic adaptions to prevailing biogeochemical conditions. One of the first study sites providing information about AOM activity in freshwater sediment is Lake Ørn, a low-sulfate, iron-rich Danish lake...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28446780/holocene-winter-climate-variability-in-central-and-eastern-europe
#9
Aurel Perșoiu, Bogdan P Onac, Jonathan G Wynn, Maarten Blaauw, Monica Ionita, Margareta Hansson
Among abundant reconstructions of Holocene climate in Europe, only a handful has addressed winter conditions, and most of these are restricted in length and/or resolution. Here we present a record of late autumn through early winter air temperature and moisture source changes in East-Central Europe for the Holocene, based on stable isotopic analysis of an ice core recovered from a cave in the Romanian Carpathian Mountains. During the past 10,000 years, reconstructed temperature changes followed insolation, with a minimum in the early Holocene, followed by gradual and continuous increase towards the mid-to-late-Holocene peak (between 4-2 kcal BP), and finally by a decrease after 0...
April 26, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28446618/the-role-of-feeding-morphology-and-competition-in-governing-the-diet-breadth-of-sympatric-stomatopod-crustaceans
#10
Maya S deVries
Competition for food drives divergence and specialization in feeding morphology. Stomatopod crustaceans have two kinds of highly specialized feeding appendages: either elongate spear-like appendages (spearers) used to ambush soft-bodied evasive prey or hammer-like appendages (smashers) that produce extremely high forces used both to break hard-shelled prey and to capture evasive prey. To evaluate associations between appendage type and feeding ecology, the diet of two small smasher and spearer species (size range: 21-27 mm) that co-occur were compared...
April 2017: Biology Letters
https://www.readbyqxmd.com/read/28446033/controls-over-spatial-and-seasonal-variations-on-isotopic-composition-of-the-precipitation-along-the-central-and-eastern-portion-of-brazil
#11
Didier Gastmans, Vinícius Santos, Juliana Aparecida Galhardi, João Felipe Gromboni, Ludmila Vianna Batista, Konrad Miotlinski, Hung Kiang Chang, José Silvio Govone
Based on Global Network Isotopes in Precipitation (GNIP) isotopic data set, a review of the spatial and temporal variability of δ(18)O and δ(2)H in precipitation was conducted throughout central and eastern Brazil, indicating that dynamic interactions between Intertropical and South Atlantic Convergence Zones, Amazon rainforest, and Atlantic Ocean determine the variations on the isotopic composition of precipitation over this area. Despite the seasonality and latitude effects observed, a fair correlation with precipitation amount was found...
April 26, 2017: Isotopes in Environmental and Health Studies
https://www.readbyqxmd.com/read/28445868/suppressionof-pyruvate-dehydrogenase-kinase-2-re-sensitizes-paclitaxel-resistant-human-lung-cancer-cells-to-paclitaxel
#12
Hong Sun, Anyou Zhu, Xiang Zhou, Fengchao Wang
Despite impressive initial clinical responses, the majority of lung cancer patients treated with paclitaxel eventually develop resistance to the drug. Pyruvate dehydrogenase kinase-2 (PDK2) is a key regulator of glycolysis and oxidative phosphorylation, and its expression is increased in a variety of tumors. In this study, the role of PDK2 in mediating paclitaxel resistance in lung cancer cells was investigated using biochemical and isotopic tracing methods. Increased expression of PDK2 was observed in paclitaxel-resistant cells ascompared totheir parental cells...
April 10, 2017: Oncotarget
https://www.readbyqxmd.com/read/28445850/simultaneous-quantification-of-busulfan-clofarabine-and-f-ara-a-using-isotope-labelled-standards-and-standard-addition-in-plasma-by-lc-ms-ms-for-exposure-monitoring-in-hematopoietic-cell-transplantation-conditioning
#13
Arjen M Punt, Jurgen B Langenhorst, Annelies C Egas, Jaap Jan Boelens, Charlotte van Kesteren, Erik M van Maarseveen
In allogeneic hematopoietic cell transplantation (HCT) it has been shown that over- or underexposure to conditioning agents have an impact on patient outcomes. Conditioning regimens combining busulfan (Bu) and fludarabine (Flu) with or without clofarabine (Clo) are gaining interest worldwide in HCT. To evaluate and possibly adjust full conditioning exposure a simultaneous analysis of Bu, F-ARA-A (active metabolite of Flu) and Clo in one analytical run would be of great interest. However, this is a chromatographical challenge due to the large structural differences of Bu compared to F-ARA-A and Clo...
April 15, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28445849/a-reference-measurement-procedure-for-amino-acids-in-blood-using-isotope-dilution-ultra-performance-liquid-chromatography-tandem-mass-spectrometry
#14
Juok Kim, Tran Thi Thanh Huong, Seon-Pyo Hong, Ji-Seon Jeong
We described a reference measurement procedure for amino acid (AA) quantification in blood samples based on deproteinization with 5-sulfosalicylic acid (SSA) and an isotope dilution-ultra performance liquid chromatography-tandem mass spectrometry (LC-MS) method. The serum was deproteinized with 15% v/v SSA and the supernatant was injected directly into the LC-MS system without further processing. Compared with the use of other precipitants and water as a control, five model AAs-valine, isoleucine, leucine, tyrosine, and phenylalanine-in the SSA-treated samples showed ionization enhancement as well as stable background signals without significant ion suppression effects...
April 17, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/28445814/comprehensive-profiling-and-characterization-of-coumarins-from-roots-stems-leaves-branches-and-seeds-of-chimonanthus-nitensoliv-using-ultra-performance-liquid-chromatography-quadrupole-time-of-flight-mass-spectrometry-combined-with-modified-mass-defect-filter
#15
Ting Tan, Yun Luo, Chen-Cong Zhong, Xu Xu, Yulin Feng
Chimonanthus nitensOliv. (CNO), having been studied and developed as the tea beverages, tea raw materials and preparations, an unique species in China, have been extensively used for treating colds and influenza for centuries. In the present study, a method based on the modified mass defect filter (MDF) was firstly developed and validated for comprehensive profiling of coumarins in the different parts of CNO via ultra-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS)...
April 17, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28445054/catalytic-decomposition-of-no-by-cationic-platinum-oxide-cluster-pt3o4
#16
Jun Yamagishi, Ken Miyajima, Satoshi Kudoh, Fumitaka Mafune
The catalytic decomposition of NO by cationic platinum oxide cluster Pt3O4+ was investigated by mass spectrometry and thermal desorption spectrometry. Upon reaction with two NO molecules, molecular oxygen desorbed from the cluster at room temperature to form Pt3O4N2+. Then, at temperatures above 400 K, desorption of N2 from Pt3O4N2+ was observed. These processes were confirmed by isotope-labeling experiments, and the energetics of O2 and N2 release were determined by density functional calculations. The combination of these elementary steps resulted in the catalytic decomposition of NO by Pt3O4+...
April 26, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28445026/chromium-poisoning-effects-on-surface-exchange-kinetics-of-la0-6sr0-4co0-2fe0-8o3-%C3%AE
#17
Yi-Lin Huang, A Mohammed Hussain, Christopher Pellegrinelli, Chunyan Xiong, Eric D Wachsman
The presence of Cr has already been reported in literature to cause severe degradation to La0.6Sr0.4Co0.2Fe0.8O3- δ (LSCF). However, fundamental understanding of Cr effects on the surface exchange kinetics is still lacking. For the first time in-situ gas phase isotopic oxygen exchange was utilized to quantitatively determine Cr effect on oxygen exchange kinetics of LSCF powder as a function of temperature and water vapor. Our investigations revealed that the formation of secondary phases, such as SrCrO¬4, Cr2O3, Cr-Co-Fe-O, and La-Co-Fe-O, can affect both the oxygen dissociation step and overall surface exchange...
April 26, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28444793/dietary-mannoheptulose-does-not-alter-glucose-or-lipid-metabolism-in-adult-labrador-retrievers
#18
L L McKnight, J France, D Wright, G Davenport, A K Shoveller
Mannoheptulose (MH), a glycolytic inhibitor, has been preliminarily investigated as a novel functional food ingredient for dogs. This study aimed to determine the effects of dietary MH, delivered as an extract of un-ripened avocados, on fatty acid and glucose kinetics in healthy adult Labrador Retriever dogs (n = 12 dogs). The study was a double-blindcrossover with each dog receiving both dietary treatments, control (CON) and MH (400 mg/kg of diet), in random order. Glucose and glycerol plasma turnover (Ra) and oxidation (Ox) were measured in fasting and in response to repeated meal feeding ("fed") with stable isotope tracers (U-(13) C-glucose, 1,1,2,3,3-D5 -glycerol) and indirect calorimetry...
April 26, 2017: Journal of Animal Physiology and Animal Nutrition
https://www.readbyqxmd.com/read/28444693/a-tiered-approach-to-evaluating-salinity-sources-in-water-at-oil-and-gas-production-sites
#19
Shawn M Paquette, Lisa J Molofsky, John A Connor, Kenneth L Walker, Harley Hopkins, Ayan Chakraborty
A suspected increase in the salinity of fresh water resources can trigger a site investigation to identify the source(s) of salinity and the extent of any impacts. These investigations can be complicated by the presence of naturally elevated total dissolved solids or chlorides concentrations, multiple potential sources of salinity, and incomplete data and information on both naturally occurring conditions and the characteristics of potential sources. As a result, data evaluation techniques that are effective at one site may not be effective at another...
April 25, 2017: Ground Water
https://www.readbyqxmd.com/read/28444356/long-term-effects-of-drought-on-tree-ring-growth-and-carbon-isotope-variability-in-scots-pine-in-a-dry-environment
#20
Galina Timofeeva, Kerstin Treydte, Harald Bugmann, Andreas Rigling, Marcus Schaub, Rolf Siegwolf, Matthias Saurer
Drought frequency is increasing in many parts of the world and may enhance tree decline and mortality. The underlying physiological mechanisms are poorly understood, however, particularly regarding chronic effects of long-term drought and the response to increasing temperature and vapor pressure deficit (VPD). We combined analyses of radial growth and stable carbon isotope ratios (δ13C) in tree rings in a mature Scots pine (Pinus sylvestris L.) forest over the 20th century to elucidate causes of tree mortality in one of the driest parts of the European Alps (Pfynwald, Switzerland)...
April 21, 2017: Tree Physiology
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