The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Etta Kafer - One of the best experts on this subject based on the ideXlab platform.
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Phenotypic and epistatic grouping of hypo- and hyper-rec mus mutants in Aspergillus
Current Genetics, 1994Co-Authors: Etta Kafer, Shun-kee ChaeAbstract:The mutants musK to musS of Aspergillus nidulans are sensitive to methyl-methanesulfonate (MMS) and several of them are meiotic-defective and alter mitotic recombination frequencies. All were found to be cross-sensitive to 4-nitro-Quinoline- N -oxide (4-NQO) but unexpectedly none of them was hypersensitive to γ-rays and few to UV light. Double mus;uvs mutants were constructed to test for interactions with uvs mutations of the four epistatic groups of Aspergillus , “UvsF”, “UvsC”, “UvsI”, and “UvsB”. All meiotic-defective mus mutations caused some lethal interactions, usually with uvsF . None of them showed epistasis with UvsF or UvsB group mutants and one, musO , may represent a new group. Three mus mutations that affect recombination were assigned to the UvsC group, namely musN and K , and also musL which is recombination-defective and closely resembles uvsC . While uvsC mutants are mutators and lack UV-mutagenesis, most mus mutants had no effects on mutation. Only musR , which appeared epistatic with uvsI , showed reduced UV-reversion frequencies similar to uvsI . The recombination-proficient mus mutants appeared to be epistatic with more than one group, but in several cases sensitivities were slight and overlaps insufficient to obtain corroborating results with MMS and 4-NQO.
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uvsI mutants defective in UV mutagenesis define a fourth epistatic group of uvs genes in Aspergillus
Current Genetics, 1993Co-Authors: Suhn-kee Chae, Etta KaferAbstract:Three UV-sensitive mutations of A. nidulans, uvsI, uvsJ and uvsA , were tested for epistatic relationships with members of the previously established groups, here called the “UvsF”, “UvsC”, and “UvsB” groups. uvsI mutants are defective for spontaneous and induced reversion of certain point mutations and differ also for other properties from previously analyzed uvs types. They are very sensitive to the killing effects of UV-light and 4-NQO (4-nitro-Quinoline- N -oxide) but not to MMS (methylmethane sulfonate). When double-and singlemutant uvs strains were compared for sensitivity to these three agents, synergistic or additive effects were found for uvsI with all members of the three groups. The uvsI gene may therefore represent a fourth epistatic group, possibly involved in mutagenic repair. On the other hand, uvsJ was clearly epistatic with members of the UvsF group and fitted well into this group also by phenotype. The uvsA gene was tentatively assigned to the UvsC group. uvsA showed epistatic interactions with uvsC in all tests, and like UvsC-group mutants is UV-sensitive mainly in dividing cells. However, the uvsA mutation does not cause the defects in recombination and UV mutagenesis typical for this group.
V. P. Andreev - One of the best experts on this subject based on the ideXlab platform.
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Crystal structure of hydrobromides of pyridines and Quinolines N-Oxides
Russian Journal of General Chemistry, 2017Co-Authors: A. V. Ryzhakov, V. P. Andreev, P. S. Sobolev, V. A. TafeenkoAbstract:Structures of hydrobromides of Quinoline, 4-methylQuinoline, pyridine, and 4-methylpyridine N -oxides have been elucidated by means of X-ray diffraction analysis. In contrast to other salts, Quinoline N -oxide hydrobromide crystallizes in the form of dimer with two water molecules. The oxygen atom of the organic molecule is coordinated with water protons, and its state is close to sp ^2-hybridization. In the cases of other hydrobromides, the oxygen atom is strongly bound to the proton of НBr and exhibits sp ^3-hybridization.
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CRYSTAL STRUCTURES AND STABILITY OF HYDRATES AND DEUTERIOHYDRATES OF Quinoline N-OxideS
European Chemical Bulletin, 2014Co-Authors: V. P. Andreev, Dmitry O. Zaitsev, Yurii A. Velikodny, Vladimir V. ChernyshevAbstract:The protiated (H 2 O) and deuteriated (D 2 O) crystallohydrates of Quinoline, 2- methylQuinoline and 4-methylQuinoline N-Oxides demonstrate different behavior at ambient conditions, namely, the deuteriated dihydrates undergo solid state transformation into crystalline anhydrous or hemihydrate forms, while protiated dihydrates loss 3D periodicity. In attempts to explain this phenomenon, the crystal structures of the six compounds – namely, Quinoline N-Oxide and Quinoline N-Oxide dihydrate, 2-methylQuinoline N-Oxide hemideuteriohydrate and 4-methylQuinoline N-Oxide dihydrate, 4-methylQuinoline N-Oxide and 4-methylQuinoline N-Oxide dihydrate – were analyzed.
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Thermal behavior of Quinoline N-Oxide hydrates and deuterohydrate
Russian Journal of General Chemistry, 2009Co-Authors: Yu. A. Gubarev, N. Sh. Lebedeva, V. P. Andreev, G. V. GirichevAbstract:Spectral and thermochemical investigation of physicochemical properties of Quinoline N -oxide crystallohydrates with H_2O and D_2O is carried out. Quinoline N -oxide is established to form with H_2O a stable dihydrate where two water molecules are energetically not equal. Complete dehydration of Quinoline N -oxide occurs when temperature reaches 150°C. With accounting for the obtained thermochenical data, Quinoline N -oxide and its mono- and dihydrates are isolated in the individual state and their IR spectra are registered and considered. It is established that at boiling Quinoline N -oxide in D_2O proceeds chemical reaction affording isoindoline-1,3-dione (phthalimide). The product is identified by elemental analysis and ^1H NMR and IR spectroscopy. The band assignment in the IR spectra of Quinoline N -oxide, phthalimide and of the complex of the latter with D_2O is based on the quantum-chemical DFT calculations.
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Thermooxidative decomposition of heterocyclic N-Oxides
Russian Journal of General Chemistry, 2007Co-Authors: Yu. A. Gubarev, N. Sh. Lebedeva, V. P. Andreev, Ya. P. Nizhnik, A. I. V’yuginAbstract:Thermooxidative decomposition of pyridine N -oxide, 4-(4-dimethylaminostyryl)pyridine N -oxide, 4-(4-methoxystyryl)pyridine N -oxide, Quinoline N -oxide, 2-methylQuinoline N -oxide, 4-chloroQuinoline N -oxide, 2-styrylQuinoline N -oxide, and 2-(4-dimethylaminostyryl)Quinoline N -oxide was studied. The kinetic parameters of the thermooxidative processes were calculated according to three independent procedures. The relation between the nature of heterocyclic N -oxide and its stability to thermal oxidation was analyzed.
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Effect of pyridine and Quinoline N-Oxides on microsomal Na,K-ATPase activity
Pharmaceutical Chemistry Journal, 2006Co-Authors: V. P. Andreev, E. G. Korvacheva, Ya. P. NizhnikAbstract:Some heteroaromatic N-Oxides of pyridine and Quinoline derivatives at concentrations ranging from 10^−4 to 10^−10 mole/liter inhibit Na,K-ATPase activity in cattle brain microsomes stronger than does strophanthin K (a drug used for the treatment of cardiac insufficiency). A new Na,K-ATPase activator, 2-(2,4-dimethoxystyryl)Quinoline-N-Oxide), has been found, which is capable of acting at concentrations within 10^−6–10^−9 mole/liter. Since these compounds activate the enzyme in very low concentrations, they can probably be effective for the treatment of some disorders involving violation of the Na,K-ATPase function.
Shun-kee Chae - One of the best experts on this subject based on the ideXlab platform.
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Phenotypic and epistatic grouping of hypo- and hyper-rec mus mutants in Aspergillus
Current Genetics, 1994Co-Authors: Etta Kafer, Shun-kee ChaeAbstract:The mutants musK to musS of Aspergillus nidulans are sensitive to methyl-methanesulfonate (MMS) and several of them are meiotic-defective and alter mitotic recombination frequencies. All were found to be cross-sensitive to 4-nitro-Quinoline- N -oxide (4-NQO) but unexpectedly none of them was hypersensitive to γ-rays and few to UV light. Double mus;uvs mutants were constructed to test for interactions with uvs mutations of the four epistatic groups of Aspergillus , “UvsF”, “UvsC”, “UvsI”, and “UvsB”. All meiotic-defective mus mutations caused some lethal interactions, usually with uvsF . None of them showed epistasis with UvsF or UvsB group mutants and one, musO , may represent a new group. Three mus mutations that affect recombination were assigned to the UvsC group, namely musN and K , and also musL which is recombination-defective and closely resembles uvsC . While uvsC mutants are mutators and lack UV-mutagenesis, most mus mutants had no effects on mutation. Only musR , which appeared epistatic with uvsI , showed reduced UV-reversion frequencies similar to uvsI . The recombination-proficient mus mutants appeared to be epistatic with more than one group, but in several cases sensitivities were slight and overlaps insufficient to obtain corroborating results with MMS and 4-NQO.
Suhn-kee Chae - One of the best experts on this subject based on the ideXlab platform.
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uvsI mutants defective in UV mutagenesis define a fourth epistatic group of uvs genes in Aspergillus
Current Genetics, 1993Co-Authors: Suhn-kee Chae, Etta KaferAbstract:Three UV-sensitive mutations of A. nidulans, uvsI, uvsJ and uvsA , were tested for epistatic relationships with members of the previously established groups, here called the “UvsF”, “UvsC”, and “UvsB” groups. uvsI mutants are defective for spontaneous and induced reversion of certain point mutations and differ also for other properties from previously analyzed uvs types. They are very sensitive to the killing effects of UV-light and 4-NQO (4-nitro-Quinoline- N -oxide) but not to MMS (methylmethane sulfonate). When double-and singlemutant uvs strains were compared for sensitivity to these three agents, synergistic or additive effects were found for uvsI with all members of the three groups. The uvsI gene may therefore represent a fourth epistatic group, possibly involved in mutagenic repair. On the other hand, uvsJ was clearly epistatic with members of the UvsF group and fitted well into this group also by phenotype. The uvsA gene was tentatively assigned to the UvsC group. uvsA showed epistatic interactions with uvsC in all tests, and like UvsC-group mutants is UV-sensitive mainly in dividing cells. However, the uvsA mutation does not cause the defects in recombination and UV mutagenesis typical for this group.
D. V. Stass - One of the best experts on this subject based on the ideXlab platform.
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S _N ^H Reaction of lithiated nitronyl nitroxide with Quinoline N-Oxide
Russian Chemical Bulletin, 2009Co-Authors: V. I. Ovcharenko, O. N. Chupakhin, I. S. Kovalev, Eugene V. Tretyakov, Galina V. Romanenko, D. V. StassAbstract:The S _N ^H reaction of lithiated 4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazole-1-oxyl 3-oxide with Quinoline N -oxide affords 4,4,5,5-tetramethyl-2-(1-oxidoquinolin-2-yl)-4,5-dihydro-1 H -imidazole-1-oxyl 3-oxide.
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SNH Reaction of lithiated nitronyl nitroxide with Quinoline N-Oxide
Russian Chemical Bulletin, 2008Co-Authors: V. I. Ovcharenko, O. N. Chupakhin, I. S. Kovalev, Eugene V. Tretyakov, Galina V. Romanenko, D. V. StassAbstract:The SNH reaction of lithiated 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl 3-oxide with Quinoline N-Oxide affords 4,4,5,5-tetramethyl-2-(1-oxidoquinolin-2-yl)-4,5-dihydro-1H-imidazole-1-oxyl 3-oxide.
