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Christopher J Reed, Theodor Agapie
A new series of tetranuclear Fe clusters displaying an interstitial μ4-F ligand was prepared for a comparison to previously reported μ4-O analogues. With a single nitric oxide (NO) coordinated as a reporter of small-molecule activation, the μ4-F clusters were characterized in five redox states, from Fe(II)3{FeNO}(8) to Fe(III)3{FeNO}(7), with NO stretching frequencies ranging from 1680 to 1855 cm(-1), respectively. Despite accessing more reduced states with an F(-) bridge, a two-electron reduction of the distal Fe centers is necessary for the μ4-F clusters to activate NO to the same degree as the μ4-O system; consequently, NO reactivity is observed at more positive potentials with μ4-O than μ4-F...
October 20, 2017: Inorganic Chemistry
Matthew V Cannon, Joseph Craine, James Hester, Amanda Shalkhauser, Ernest R Chan, Kyle Logue, Scott Small, David Serre
The study of the microbial communities has gained traction in recent years with the advent of next-generation sequencing with, or without, PCR-based amplification of the 16S ribosomal RNA region. Such studies have been applied to topics as diverse as human health and environmental ecology. Fewer studies have investigated taxa outside of bacteria, however. We present here data demonstrating the utility of studying taxa outside of bacteria including algae, diatoms, archaea and fungi. Here, we show how location along the Cuyahoga River as well as a transient rainfall event heavily influence the microbial composition...
2017: PloS One
(no author information available yet)
The objective of the present work was to study the structure of epiphyton in water bodies significantly differing in the degree of their contamination. In the studied water bodies, the concentration of ammonia (NH4+-N) accounted for 0.04-74.00 mg/L, nitrite (NO2--N) - 0.002-1.750 mg/L, nitrate (NO3--N) - 0.13-58.00 mg/L, inorganic compounds of phosphorus (Pinorg) - 0.041-0.272 mg/L, chloride (Cl-) - 34.5-560.5 mg/L, whereas the content of organic matter (DO) - 18.0-81.0 mg O/L. The numbers of algae were determined by the method of a direct count...
October 17, 2017: Water Environment Research: a Research Publication of the Water Environment Federation
Benoit Tesson, Sarah J L Lerch, Mark Hildebrand
Diatoms are known for their intricate, silicified cell walls (frustules). Silica polymerization occurs in a compartment called the silica deposition vesicle (SDV) and it was proposed that the cytoskeleton influences silica patterning through the SDV membrane (silicalemma) via interactions with transmembrane proteins. In this work we identify a family of proteins associated with the silicalemma, named SAPs for Silicalemma Associated Proteins. The T. pseudonana SAPs (TpSAPs) are characterized by their motif organization; each contains a transmembrane domain, serine rich region and a conserved cytoplasmic domain...
October 18, 2017: Scientific Reports
Mimmi Oksman, Kaarina Weckström, Arto Miettinen, Stephen Juggins, Dmitry V Divine, Rebecca Jackson, Richard Telford, Niels J Korsgaard, Michal Kucera
The transition from the last ice age to the present-day interglacial was interrupted by the Younger Dryas (YD) cold period. While many studies exist on this climate event, only few include high-resolution marine records that span the YD. In order to better understand the interactions between ocean, atmosphere and ice sheet stability during the YD, more high-resolution proxy records from the Arctic, located proximal to ice sheet outlet glaciers, are required. Here we present the first diatom-based high-resolution quantitative reconstruction of sea surface conditions from central-eastern Baffin Bay, covering the period 14...
October 18, 2017: Nature Communications
Ryan A Vandermeulen, Antonio Mannino, Aimee Neeley, Jeremy Werdell, Robert Arnone
Using a modified geostatistical technique, empirical variograms were constructed from the first derivative of several diverse Remote Sensing Reflectance and Phytoplankton Absorbance spectra to describe how data points are correlated with "distance" across the spectra. The maximum rate of information gain is measured as a function of the kurtosis associated with the Gaussian structure of the output, and is determined for discrete segments of spectra obtained from a variety of water types (turbid river filaments, coastal waters, shelf waters, a dense Microcystis bloom, and oligotrophic waters), as well as individual and mixed phytoplankton functional types (PFTs; diatoms, eustigmatophytes, cyanobacteria, coccolithophores)...
August 7, 2017: Optics Express
Matthew B Parks, Norman J Wickett, Andrew J Alverson
Diatoms (Bacillariophyta) are a species-rich group of eukaryotic microbes diverse in morphology, ecology, and metabolism. Previous reconstructions of the diatom phylogeny based on one or a few genes have resulted in inconsistent resolution or low support for critical nodes. We applied phylogenetic paralog pruning techniques to a dataset of 94 diatom genomes and transcriptomes to infer perennially difficult species relationships, using concatenation and summary-coalescent methods to reconstruct species trees from datasets spanning a wide range of thresholds for taxon and column occupancy in gene alignments...
October 12, 2017: Molecular Biology and Evolution
K E Roberts, S F Lamoureux, T K Kyser, D C G Muir, M J Lafrenière, D Iqaluk, A J Pieńkowski, A Normandeau
Permafrost exerts an important control over hydrological processes in Arctic landscapes and lakes. Recent warming and summer precipitation has the potential to alter water availability and quality in this environment through thermal perturbation of near surface permafrost and increased mobility of previously frozen solutes to Arctic freshwaters. We present a unique thirteen-year record (2003-16) of the physiochemical properties of two High Arctic lakes and show that the concentration of major ions, especially SO4(2-), has rapidly increased up to 500% since 2008...
October 16, 2017: Scientific Reports
Tengda Ding, Kunde Lin, Mengting Yang, Lianjun Bao, Juying Li, Bo Yang, Jay Gan
Triclosan (TCS) is one of the most widely used pharmaceutically active compounds and frequently detected in treated wastewater and the impacted aquatic environment. However, the fate and toxicity of TCS in aquatic organisms is poorly known, including in particular the potential for the formation of incomplete biological transformation products. In this study, TCS posed high toxic effects (e.g., growth inhibition and damage of photosynthesis) to typical freshwater diatom Navicula sp., with the 24h and 72h EC50 values of 173...
September 21, 2017: Journal of Hazardous Materials
Paul C Kusnierz, Christopher M Holbrook
Bed stability is an important stream habitat attribute because it affects geomorphology and biotic communities. Natural resource managers desire indices of bed stability that can be used under a wide range of geomorphic conditions, are biologically meaningful, and are easily incorporated into sampling protocols. To eliminate potential bias due to presence of instream wood and increase precision of stability values, we modified a stream bed instability index (ISI) to include measurements of bankfull depth (d bf) and median particle diameter (D 50) only in riffles and increased the pebble count to decrease variability (i...
October 16, 2017: Environmental Monitoring and Assessment
Ja-Myung Kim, Oliver Baars, François M M Morel
A poorly studied but potentially important consequence of the CO2-induced acidification of the surface ocean is a possible change in the bioavailability of trace metals, which play a critical role in the productivity and population dynamics of marine ecosystems. We report laboratory and field experiments designed to compare quantitatively the effects of acidification on the bioavailability of Zn, a metal essential to the growth of phytoplankton and on the extent of its complexation by model and natural ligands...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Yingju Yang, Jing Liu, Feng Liu, Zhen Wang, Sen Miao
Natural pyrite (FeS2) has been regarded as a kind of potential sorbents to control mercury emission from coal-fired power plants because of its low cost and high affinity between mercury and FeS2. Theoretical investigations based on density functional theory (DFT) were carried out to discern mercury adsorption, reaction and desorption mechanisms over pyrite surface. DFT calculation results indicate that Hg(0) adsorption on FeS2(100) and FeS2(110) surfaces is dominated by physisorption and chemisorption mechanisms, respectively...
October 7, 2017: Journal of Hazardous Materials
Antonio J Pazos, Pablo Ventoso, Roi Martínez-Escauriaza, M Luz Pérez-Parallé, Juan Blanco, Juan C Triviño, José L Sánchez
Bivalve molluscs are filter feeding species that can accumulate biotoxins in their body tissues during harmful algal blooms. Amnesic Shellfish Poisoning (ASP) is caused by species of the diatom genus Pseudo-nitzschia, which produces the toxin domoic acid. The Mytilus galloprovincialis digestive gland transcriptome was de novo assembled based on the sequencing of 12 cDNA libraries, six obtained from control mussels and six from mussels naturally exposed to domoic acid-producing diatom Pseudo-nitzschia australis...
October 11, 2017: Toxicon: Official Journal of the International Society on Toxinology
Maxime C Bridoux, Monika Sobiechowska, Alicia Pérez-Fuentetaja, Katherine T Alben
Carotenyl fatty acid esters (carotenyl-FAEs) were extracted in acetone from freeze-dried Dreissena bugensis (Lakes Erie and Ontario) and hydrolyzed to identify the carotenoid precursors. Analysis by liquid chromatography (LC) with photodiode array (PDA) and atmospheric pressure chemical ionization-ion trap mass spectrometry (APCIitMS) revealed the major hydrolysis products: fucoxanthinol (FOH) from fucoxanthin (FX, diatoms); mactraxanthin (MX) from violaxanthin (VX, chlorophytes); 4-fold higher levels of an unknown, tentatively identified as an adduct of two closely eluting C27H46O3 and C27H48O3 steryl triols...
October 13, 2017: Analytical and Bioanalytical Chemistry
Yue Lei, Callum Whyte, Keith Davidson, Paul Tett, Kedong Yin
Water quality in Tolo Harbour and Channel (Tolo) has been improved since 1998 after the diversion of sewage effluent. However, it remains poorly understood how nutrient loading reduction has impacted the phytoplankton community. To evaluate this, we applied a Phytoplankton Community Index PI(mp) to the 23-year data (1991-2013) at inner (TM4) and outer (TM8) sites in Tolo, with the former being more eutrophic than the latter. The results show that 1) the phytoplankton community changed with time after sewage diversion; 2) "diatoms and dinoflagellates" were better indicators of nutrient impact than "autotrophic/mixotrophic and heterotrophic dinoflagellates"; 3) the rate of recovery differed between the two stations, but both reached a similar state at a similar time; 4) seasonality of the phytoplankton community showed greater disturbance in spring than in other seasons...
October 10, 2017: Marine Pollution Bulletin
Vincent Hervé, Boris Leroy, Albert Da Silva Pires, Pascal Jean Lopez
In most cities, streets are designed for collecting and transporting dirt, litter, debris, storm water and other wastes as a municipal sanitation system. Microbial mats can develop on street surfaces and form microbial communities that have never been described. Here, we performed the first molecular inventory of the street gutter-associated eukaryotes across the entire French capital of Paris and the non-potable waters sources. We found that the 5782 OTUs (operational taxonomic units) present in the street gutters which are dominated by diatoms (photoautotrophs), fungi (heterotrophs), Alveolata and Rhizaria, includes parasites, consumers of phototrophs and epibionts that may regulate the dynamics of gutter mat microbial communities...
October 13, 2017: ISME Journal
Takuro Nakayama, Yuji Inagaki
Organelle acquisitions via endosymbioses with prokaryotes were milestones in the evolution of eukaryotes. Still, quite a few uncertainties have remained for the evolution in the early stage of organellogenesis. In this respect, rhopalodiacean diatoms and their obligate cyanobacterial endosymbionts, called spheroid bodies, are emerging as new models for the study of organellogenesis. The genome for the spheroid body of Epithemia turgida, a rhopalodiacean diatom, has unveiled its unique metabolic nature lacking the photosynthetic ability...
October 12, 2017: Scientific Reports
K Hardge, S Neuhaus, E S Kilias, C Wolf, K Metfies, S Frickenhaus
Next-generation sequencing is a common method for analyzing microbial community diversity and composition. Configuring an appropriate sequence processing strategy within the variety of tools and methods is a non-trivial task and can considerably influence the resulting community characteristics. We analyzed the V4 region of 18S rRNA gene sequences of marine samples by 454-pyrosequencing. Along this process, we generated several data sets with QIIME, mothur and a custom-made pipeline based on DNAStar and the phylogenetic-tree based PhyloAssigner...
October 12, 2017: Molecular Ecology Resources
Luis Alvarez-Thon, Liliana Mammino
Magnetically induced current densities are different for different types of chemical bonds, and may help highlight some of their characteristics and stress their main differences. The present work considers magnetically induced current densities in the bonds of diatomic molecules bonded by covalent bonds as well as the gas phase molecules of 1:1 ionic compounds, comparing the current strength values and visualizing current density maps. The results show clear-cut differences for the different types of bonds (non-polar covalent, polar covalent, and ionic), and can also be related to the extent of the covalent or ionic character of a bond...
October 12, 2017: Journal of Computational Chemistry
Sophia I Passy
To understand how communities function and generate abundance, I develop a framework integrating elements from the stress gradient and resource partitioning concepts. The framework suggests that guild abundance depends on environmental and spatial factors but also on inter-guild interactions (competitor or facilitator richness), which can alter the fundamental niche of constituent species in negative (competition) or positive direction (facilitation). Consequently, the environmental and spatial mechanisms driving guild abundance would differ across guilds and interaction modes...
2017: PeerJ
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