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https://www.readbyqxmd.com/read/28545113/rac1-is-dispensable-for-oocyte-maturation-and-female-fertility-in-vivo
#1
Jian-Xiu Hao, Tie-Gang Meng, Li-Hua Fan, Yuan-Qing Yao
Oocyte maturation, the important process to produce female haploid gamete, accompanies with polarity establishment and highly asymmetric cell division to emit minor polar body within little cytoplasm. Microfilaments play central roles in polarity establishment and asymmetric cell division. Several actin regulators like WASP protein family as well as small GTPases function in microfilament dynamics, involving the process. Rac1, one member of RhoGTPases, has been reported to regulate the polarity and asymmetric cell division in mouse oocytes in vitro...
2017: PloS One
https://www.readbyqxmd.com/read/28544998/chronic-toxicity-of-five-metals-to-the-polar-marine-microalga-cryothecomonas-armigera-application-of-a-new-bioassay
#2
Darren J Koppel, Francesca Gissi, Merrin S Adams, Catherine K King, Dianne F Jolley
The paucity of ecotoxicological data for Antarctic organisms is impeding the development of region-specific water quality guidelines. To address this limitation, toxicity testing protocols need to be developed to account for the unique physiology of polar organisms, in particular their slow growth rates. In this study, a toxicity test protocol was developed to investigate the toxicities of five metals to the polar marine microalga Cryothecomonas armigera. The concentrations which reduced population growth rate by 10% (EC10) after 24-d for Cu, Pb, Zn, Cd and Ni were 21...
May 22, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28544941/time-based-expectations-entail-preparatory-motor-activity
#3
Gregor Volberg, Roland Thomaschke
Human behavior is guided by expectations that facilitate perception of upcoming events or reaction to them. In natural settings expectations are often implicitly based on time, e.g., when making a phone call one would expect to hear either a person answering (earlier) or a voicemail greeting (later). We investigated how time-based expectations can improve performance in the absence of explicit prior information on the pending stimulus or the associated response. Visual stimuli were presented after a characteristic short or long foreperiod, and a forced-choice categorization using either the left or the right hand was required...
May 4, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/28544915/pyrrole-based-poly-ionic-liquids-as-efficient-stabilizers-for-formation-of-hollow-multi-walled-carbon-nanotubes-particles
#4
Prithwish Chatterjee, Elizabeth M Nofen, Wenwen Xu, Conrad Hom, Hanqing Jiang, Lenore L Dai
Poly(ionic liquid) (PIL) derivatives with pyrrole intrinsically conducting polymer (ICP) backbones were synthesized and utilized as novel dispersants of multi-walled carbon nanotubes (MWCNTs) in various aqueous and non-aqueous systems, including polar and nonpolar solvents. This is due to the highly tunable nature of the PIL, in which the PILs of varying polarity with the same pyrrole-based polycation can be synthesized. The dispersions are exceedingly stable over many months, and with the addition of hexane, Pickering (solid-stabilized) emulsions with the PIL-stabilized MWCNTs at the droplet interfaces were formed...
April 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28544729/comparative-study-of-two-chemical-protocols-for-creating-white-spot-lesions-an-in-vitro-fluorecam-evaluation
#5
Moufida Abufarwa, Amal Noureldin, Phillip M Campbell, Peter H Buschang
AIM: The aim of the present study was to compare the effectiveness and practicality of two commonly-used protocols for white spot lesion creation. METHODS: Sound posterior human teeth were sectioned into halves and randomly allocated into two groups (n=20). Using the FluoreCam system, the enamel surfaces were imaged under standardized conditions, and baseline data (area, intensity, and impact) were recorded. Specimens were covered with an acid-resistant polish, leaving a 2×6-mm enamel window...
May 23, 2017: Journal of Investigative and Clinical Dentistry
https://www.readbyqxmd.com/read/28544574/reversing-polarity-carbonyl-%C3%AE-aminations-with-nitrogen-nucleophiles
#6
Aurelien de la Torre, Veronica Tona, Nuno Maulide
The synthesis of alpha-amino carbonyl compounds is an important challenge in synthesis en route to biologically essential structures. While classical approaches involve the use of enol or enolate chemistries in combination with an electrophilic source of nitrogen, those strategies usually necessitate further transformations in order to reach the desired targets. In recent years, a new approach arose involving the direct use of nucleophilic sources of nitrogen along with an oxidant. This advantageously leads in one-pot to the biologically relevant alpha-amino compounds, without further transformation required...
May 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544566/aqueous-oxidations-started-by-tio%C3%A2-photo-induced-holes-can-be-a-rate-determining-step
#7
Yuanzheng Gong, Chun Yang, Hongwei Ji, Chuncheng Chen, Wanhong Ma, Jincai Zhao
In aqueous TiO2 photocatalytic hydroxylation of weakly polar aromatics, unlike usual polar aromatic cases of normal H/D KIEs, a series of inverse H/D KIEs of 0.7~0.8 were observed, which indicated that the oxidtion started by photo-induced hvb+ can be the rate-determining step.
May 23, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28544563/enantiopure-cycloiridiated-complexes-bearing-a-pentahelicenic-n-heterocyclic-carbene-and-displaying-long-lived-circularly-polarized-phosphorescence
#8
Jeanne Crassous, Nora Hellou, Monika Srebro-Hooper, Ludovic Favereau, Francesco Zinna, Elsa Caytan, Loic Toupet, Vincent Dorcet, Marion Jean, Nicolas Vanthuyne, Gareth Williams, Lorenzo Di Bari, Jochen Autschbach
A fused pi-helical N-heterocyclic (NHC) system has been prepared and examined through its diastereoisomerically pure cycloiridiated complexes. The latter display light-green phosphorescence with i) unusually long lifetimes and ii) circular polarization that depends on both the helical-NHC P/M and the iridium delta/lambda stereochemistry. These unprecedented features are attributed to extended pi-conjugation within helical carbenic ligand and efficient helicene-NHC-Ir interaction.
May 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544353/chiral-separation-of-12-pairs-of-enantiomers-by-capillary-electrophoresis-using-heptakis-2-3-diacetyl-6-sulfato-%C3%AE-cyclodextrin-as-the-chiral-selector-and-the-elucidation-of-the-chiral-recognition-mechanism-by-computational-methods
#9
Yaqi Yao, Peilu Song, Xiaoli Wen, Miaoduo Deng, Jian Wang, Xingjie Guo
Chiral separation of 12 pairs of basic analyte enantiomers including oxybutynin, bambuterol, tradinterol, clenbuterol, clorprenaline, terbutaline, tulobuterol, citalopram, phencynonate, fexofenadine, salbutamol and penehyclidine was conducted by capillary electrophoresis using a single-isomer anionic β-cyclodextrin derivative, heptakis-(2,3-diacetyl-6-sulfato)-β-cyclodextrin as the chiral selector. Parameters influencing separation were studied, including background electrolyte pH, heptakis-(2,3-diacetyl-6-sulfato)-β-cyclodextrin concentration, buffer concentration and separation voltage...
May 24, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28544270/localization-and-domain-characterization-of-the-sfla-regulator-of-flagellar-formation-in-vibrio-alginolyticus
#10
Satoshi Inaba, Takehiko Nishigaki, Norihiro Takekawa, Seiji Kojima, Michio Homma
Many swimming bacteria use flagella as locomotive organelles. The spatial and numerical regulation of flagellar biosynthesis differs by bacterial species. The marine bacteria Vibrio alginolyticus use a single polar flagellum whose number is regulated positively by FlhF and negatively by FlhG. Cells lacking FlhF and FlhG have no flagellum. The motility defect in an flhFG deletion was suppressed by a mutation in the sflA gene that resulted in the production of multiple, peritrichous flagella. SflA is a Vibrio-specific protein...
May 22, 2017: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
https://www.readbyqxmd.com/read/28544207/application-of-linear-gradient-elution-in-countercurrent-chromatography-for-the-separation-of-triterpenoid-saponins-from-the-roots-of-pulsatilla-koreana-nakai
#11
Kyoung Jin Lee, Kwangho Song, Da Young Song, Yeong Shik Kim
A linear gradient elution method using countercurrent chromatography was developed for the separation of four triterpenoid saponins from the roots of Pulsatilla koreana Nakai, including hederacolchiside E, which is responsible for the neuroprotective activity of this plant. The target fraction was obtained by 80% methanol elution of solid phase column chromatography. The partition coefficients of the target compounds were very different, which means they are difficult to separate with a single biphasic solvent system...
May 19, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28544199/benzhydryl-ethers-of-tartaric-acid-derivatives-stereochemical-response-of-dynamically-chiral-propeller
#12
Jakub Grajewski, Tomasz Mądry, Marcin Kwit, Beata Beata Warżajtis, Urszula Rychlewska, Jacek K Gawronski
The benzhydryl (diphenylmethyl) group is a molecular propeller that can acts as a chirality reporter when it is introduced nearby the stereogenic center by making the ether bond. Hydrophobic character of the benzhydryl group allows transformation of insoluble in non-polar environment natural tartaric acid derivatives into soluble entities. Electronic circular dichroism spectra, recorded within the short wavelength region of the phenyl 1B transitions (190-200 nm) showed strong bisignate Cotton effects. The signs and magnitudes of these Cotton effects are a function of absolute configuration and conformation of the molecule and primarily are not due to exciton coupling of chiral benzhydryl chromophores...
May 23, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28544173/frozen-acrylamide-gels-as-dynamic-nuclear-polarization-matrices
#13
Jasmine Viger-Gravel, Pierrick Berruyer, David Gajan, Jean-Marie Basset, Anne Lesage, Paul Tordo, Olivier Ouari, Lyndon Emsley
We show that aqueous acrylamide gels can be used to provide dynamic nuclear polarization (DNP) NMR signal enhancements of around 200 at 9.4 T and 100 K. The enhancements are shown to increase with cross linker concentration and low concentrations of the AMUPol biradical. We show that this DNP matrix can be used in situations where conventional incipient wetness methods fail, such as to obtain DNP surface enhanced NMR spectra from inorganic nanoparticles. In particular, we obtain 113Cd spectra from CdTe-COOH NPs in minutes...
May 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544124/secondary-structure-driven-self-assembly-of-reactive-polypept-o-ides-controlling-size-shape-and-function-of-core-cross-linked-nanostructures
#14
Kristina Klinker, Olga Schäfer, David Huesmann, Tobias Bauer, Leon Capelôa, Lydia Braun, Natascha Stergiou, Meike Schinnerer, Anjaneyulu Dirisala, Kanjiro Miyata, Kensuke Osada, Horacio Cabral, Kazunori Kataoka, Matthias Barz
Achieving precise control over morphology and function of polymeric nanoparticles during self-assembly remains a challenge in material as well as bio-medical sciences, especially when all these properties can be controlled independently. Herein, we report on nanostructures derived from amphiphilic block copolypept(o)ides by secondary structure directed self-assembly, presenting a strategy to adjust core polarity separately from particle preparation in a bio-reversible fashion. The peptide-inherent process of secondary structure-formation allows for the synthesis of spherical and worm-like core cross-linked architectures from the same block copolymer, introducing a simple yet powerful approach to versatile peptide-based nanoparticles...
May 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544115/unprecedented-carbon-signal-enhancement-in-liquid-state-nmr-spectroscopy
#15
György Pintér, Harald Schwalbe
We shall overcome: As a result of efforts to overcome the sensitivity challenge of liquid-state NMR spectroscopy, a thousand-fold signal enhancement was achieved by dynamic nuclear polarization (DNP) for (13) C signals at high magnetic field (3.4 T) and room temperature, thereby exceeding the predicted limitations of high-field liquid-state in situ DNP.
May 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544001/lipophilic-n-hydroxyphthalimide-catalysts-for-the-aerobic-oxidation-of-cumene-towards-solvent-free-conditions-and-back
#16
Manuel Petroselli, Lucio Melone, Massimo Cametti, Carlo Punta
A new class of lipophilic N-hydroxyphthalimides catalysts designed for the aerobic oxidation of cumene in solvent-free conditions were synthesized and tested. The specific strategy proposed for the introduction of lipophilic tails on the NHPI moiety leads to lipophilic catalysts which, while completely preserving the activity of the precursor, allow to conduct the catalytic oxidation in neat cumene for the very first time. The corresponding cumyl hydroperoxide is obtained in good yields (28-52%) and high selectivity (95-97%), under mild conditions...
May 24, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28543966/development-of-a-quantitative-assessment-method-of-pigmentary-skin-disease-using-ultraviolet-optical-imaging
#17
Onseok Lee, Sunup Park, Jaeyoung Kim, Chilhwan Oh
BACKGROUND/PURPOSE: The visual scoring method has been used as a subjective evaluation of pigmentary skin disorders. Severity of pigmentary skin disease, especially melasma, is evaluated using a visual scoring method, the MASI (melasma area severity index). This study differentiates between epidermal and dermal pigmented disease. The study was undertaken to determine methods to quantitatively measure the severity of pigmentary skin disorders under ultraviolet illumination. METHODS: The optical imaging system consists of illumination (white LED, UV-A lamp) and image acquisition (DSLR camera, air cooling CMOS CCD camera)...
May 21, 2017: Skin Research and Technology
https://www.readbyqxmd.com/read/28543804/au-i-%C3%A2-%C3%A2-%C3%A2-au-i-interaction-assisted-host-guest-interactions-and-stimuli-responsive-self-assembly-in-tetranuclear-alkynylgold-i-calix-4-arene-based-isocyanide-complexes
#18
Anlea Chu, Franky Ka-Wah Hau, Vivian W W Yam
Multi-stimuli-responsive tetranuclear gold(I) complexes have been prepared based on a tetra(alkynyl)calix[4]arene framework, with incorporation of a series of isocyanide ligands of tunable hydrophilicity. This class of complexes is found to exhibit high sensitivity towards group IIIA metal ions especially indium(III) ions. Drastic electronic absorption and emission changes have been observed, which could be attributed to the formation of Au(I)···Au(I) interactions during the binding event. Solvent-induced self-aggregation has also been observed upon changing the solvent environment to a more polar medium, with the formation of nanoaggregates and the turning on of the aurophilic interactions, leading to interesting luminescence and morphological changes...
May 21, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28543587/optical-mapping-of-nonmelanoma-skin-cancers-a-pilot-clinical-study
#19
Anna N Yaroslavsky, Xin Feng, Victor A Neel
BACKGROUND AND OBJECTIVE: Nonmelanoma skin cancer (NMSC) is the most common human cancer. Because these tumors often affect the face, there is a strong need for both accurate removal of these neoplasms to prevent recurrence and maximal tissue preservation to prevent cosmetic or functional deformity. Polarization-enhanced reflectance and fluorescence imaging (PERFI) is a new bedside method that uses fluorescent chromophores to image NMSC. While the feasibility of the technique has been successfully demonstrated in ex vivo studies, this is the first pilot study to extend the use of PERFI to in vivo intraoperative imaging of NMSC...
May 23, 2017: Lasers in Surgery and Medicine
https://www.readbyqxmd.com/read/28543308/exocytic-trafficking-pathways-in-plants-why-and-how-they-are-redirected
#20
REVIEW
Takehiko Kanazawa, Takashi Ueda
The membrane trafficking system is responsible for precise transportation and localization of proteins, lipids, and polysaccharides among single membrane-bound organelles, the plasma membrane, and the extracellular space. While the exocytic trafficking pathway is considered to be a default transport pathway in many organisms, including land plants, research has shown that evolutionary processes led to an increase in the number of machinery components involved in the plant exocytic pathway. This study provides an overview of the diversification of exocytic trafficking pathways in plants, which mediate the formation and maintenance of cell polarity, interaction with symbiotic and pathogenic microbes, and cytokinesis...
May 25, 2017: New Phytologist
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