scholarly journals The influence of chromatin compactness on the stoichiometry of the Feulgen-Schiff procedure studied in model films. II. Investigations on films containing condensed or swollen chicken erythrocyte nuclei.

1975 ◽  
Vol 23 (12) ◽  
pp. 891-900 ◽  
Author(s):  
W A Duijndam ◽  
P van Duijn
Keyword(s):  
Staining Intensity ◽  
Nuclear Material ◽  
Reaction Products ◽  
Chromatin Compactness ◽  
High Reduction ◽  
Protein Components ◽  
Schiff Reaction ◽  
Chicken Erythrocytes ◽  
Aldehyde Groups ◽  
Very High

As models for different states of chromatin compactness, nuclei from chicken erythrocytes were isolated and either osmotically swollen or kept as condensed as possible. Both types of nuclei were then fixed and incorporated into polyacrylamide films. Hydrolysis with 5 N HCl and staining with Schiff's reagent of these model films were studied using several parameters. The phosphate content of the films was analyzed as a parameter for the depolymerization losses and the staining with Schiff's reagent as a parameter for the apurinic acid (APA) content. The loss of ultraviolet absorbance from the films and the accumulation of ultraviolet absorbing substances in the hydrolyzing acid were monitored as parameters for the progress of hydrolysis. Conversion of the generated aldehyde groups to APA-Schiff chromophore is shown to take place with the same stoichiometry for both types of nuclei as well as for DNA in model films. It is further shown that the nuclei- and DNA-films are suitable models for investigating the influence of chromatin compactness on the course of the Feulgen-Schiff reaction. For the most compact form of chromatin studied, a very high reduction in staining intensity of up to 40% could be demonstrated after certain normally applied hydrolysis times. This is due primarily to a decrease with a factor of 2.3 of the depurination rate constants of these models (from 0.030/min to 0.013/min). Therefore prolonged hydrolysis periods are required to obtain the same APA concentrations, but then depolymerization processes cause losses of nuclear material. The differences in depurination rates could be explained by a decrease in [H3O]+ in the neighborhood of the purine-sugar linkages, caused by the presence of fixed positive charges form the protein components of the chromatin. These findings may explain the cytophotometrically determined differences in chromophore yield of 10-20% found in the nuclei of cells with different states of compactness of their chromatin. The descending part of the Feulgen hydrolysis curve represents the depolymerization of APA and loss by diffusion of the reaction products. In the Appendix, cytophotometric data of cells have been analyzed to show that this part of the hydrolysis curve may be used to estimate the acid stability of chromatin complexes. The depurination and depolymerization rates found closely correspond with the data obtained from the model films.

scholarly journals THE PERIODATE-SCHIFF REACTION: SPECIFICITY, KINETICS, AND REACTION PRODUCTS WITH PURE SUBSTRATES

1965 ◽  
Vol 13 (6) ◽  
pp. 423-430 ◽  
Author(s):  
ARNE DAHLQVIST ◽  
INGE OLSSON ◽  
ÅKE NORDÉN
Keyword(s):  
Nucleic Acids ◽  
Simple Relation ◽  
Test Tube ◽  
Reaction Products ◽  
Chromatographic Mobility ◽  
Reaction Specificity ◽  
Rate Of Reaction ◽  
Pure Substances ◽  
Schiff Reaction ◽  
Aldehyde Groups

A quantitative test-tube method has been used to study the periodate-Schiff reaction of a number of pure substances. The rate of reaction, the amount of color produced, and in some cases the amount of periodate consumed, have been measured. The dye produced by different carbohydrates has been analyzed by spectrophotometry and paper chromatography. Glycogen, starch and dextran reacted slowly and produced much less color than the corresponding amount of free monosaccharides. Oligosaccharides and heteropolysaccharides were either periodate-Schiff-negative or very weakly positive. Proteins and nucleic acids were negative. There was no simple relation between the intensity of the periodate-Schiff reaction and the amount of periodate consumed or the amount of aldehyde groups formed on the oxidation by periodate. The dyes formed with different carbohydrates had essentially the same absorption curve, but differed in their chromatographic mobility.

scholarly journals Unveiling Extreme Photoreduction Potentials of Donor-Acceptor Cyanoarenes to Access Aryl Radicals from Aryl Chlorides

2021 ◽  
Author(s):  
Jinhui Xu ◽  
Jilei Cao ◽  
Xiangyang Wu ◽  
Han Wang ◽  
Xiaona Yang ◽  
...  
Keyword(s):  
Limited Range ◽  
Redox Potentials ◽  
Aryl Chlorides ◽  
Aryl Radicals ◽  
Reduction Potentials ◽  
Anion Form ◽  
Donor Acceptor ◽  
High Reduction ◽  
Very High ◽  
Excited Radical

Since the seminal work of Zhang in 2016, donor-acceptor cyanoarene-based fluorophores, such as 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), have been widely applied in photoredox catalysis, and used as excellent metal-free alternatives to noble metal Ir- and Ru-based photocatalysts. However, all the reported photoredox reactions involving this chromophore family are based on harnessing the energy from a single visible light photon, with a limited range of redox potentials from -1.92 V to +1.79 V. Here, we document the unprecedented discovery that this family of fluorophores can undergo consecutive photoinduced electron transfer (ConPET) to achieve very high reduction potentials. One of the newly synthesized catalysts, 2,4,5-tri(9H-carbazol-9-yl)-6-(ethyl(phenyl)amino)isophthalonitrile (3CzEPAIPN), possesses a long-lived (12.95 ns) excited radical anion form, 3CzEPAIPN<sup>•</sup><sup>−</sup>*, which can be used to activate reductively recalcitrant aryl chlorides (E<sub>red </sub>≈ -1.9 to -2.9 V) under mild conditions. The resultant aryl radicals can be engaged in synthetically valuable aromatic C-B, C-P, and C-C bond formation to furnish arylboronates, arylphosphonium salts, arylphosphonates, and spirocyclic cyclohexadienes, respectively.

scholarly journals Characterization of a Tricationic Trigonal Bipyramidal Iron(IV) Cyanide Complex, with a Very High Reduction Potential, and Its Iron(II) and Iron(III) Congeners

2011 ◽  
Vol 50 (7) ◽  
pp. 2885-2896 ◽  
Author(s):  
Jason England ◽  
Erik R. Farquhar ◽  
Yisong Guo ◽  
Matthew A. Cranswick ◽  
Kallol Ray ◽  
...  
Keyword(s):  
Reduction Potential ◽  
Cyanide Complex ◽  
Trigonal Bipyramidal ◽  
High Reduction ◽  
Very High

Characterizing the Shear Deformation during Asymmetric Rolling

2008 ◽  
Vol 584-586 ◽  
pp. 327-332 ◽  
Author(s):  
Yun Long Chen ◽  
Ai Dang Shan ◽  
Jian Hua Jiang ◽  
Yi Ding
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Shear Deformation ◽  
Room Temperature ◽  
Pure Aluminum ◽  
Asymmetric Rolling ◽  
Metallic Material ◽  
Side Face ◽  
High Reduction ◽  
Very High

Asymmetric rolling has been considered as a possible way to obtain severe plastic deformation (SPD) since it will give an extra shear deformation to the processed materials during rolling. Previous researches have confirmed such a shear deformation. Very recently, the method of inserting-block is used to characterize the shear deformation through direct observation, but when the reduction is more than 70%, the lineation scratched on the side face of internal mark becomes vague and illegible. In order to directly observe the shear deformation of metallic material with large reduction, the internal mark method is employed in this research and asymmetric rolling was performed with pure aluminum and iron at room temperature. In severe plastic deformation, the shear deformation caused by asymmetric rolling was clearly observed and measured through employing internal mark method. Remarkable extra shear deformation during asymmetric rolling was confirmed. Very high equivalent strains were achieved when sheet samples were asymmetrically rolled to high reduction ratio. These strain values fall into the range of SPD.

scholarly journals Efficacy of spirotetramat in the control of the currant-sowthistle (Hyperomyzus lactucae l.) on blackcurrant plantations in Poland

2013 ◽  
Vol 21 (2) ◽  
pp. 73-78 ◽  
Author(s):  
Barbara H. Łabanowska ◽  
Mirosław Korzeniowski ◽  
Tomasz Gasparski
Keyword(s):  
Single Treatment ◽  
Dose Rates ◽  
High Reduction ◽  
Very High

ABSTRACT Spirotetramat applied as Movento 100 SC at dose rates: 0.7 and 1.0 L·ha-1 in a single treatment just after blossom resulted in a very high reduction of currant-sowthistle aphid - Hyperomyzus lactucae L. (Aphidoidea, Aphididae) on blackcurrants ‘Ojebyn’ and ‘Titania’. The results obtained with this pesticide applied at both tested dose rates: 0.7 and 1.0 L·ha-1 were comparable. The efficacy of spirotetramat at 7th day after treatment was similar or slightly poorer compared to standard insecticides, but at 21st day after treatment a higher reduction of aphids than with reference insecticides such as pirimicarb (Pirimor 500 WG at the rate 0.75 kg·ha-1), thiacloprid (Calypso 480 SC 0.15 L·ha-1) and thiamethoxam (Actara 25 WG at the rate 0.1 kg·ha-1) was recorded. With regard to environment safety and biodiversity it must be underlined that on plants treated with Movento 100 SC, high populations of Coccinellidae (both larvae and beetles), Syrphidae (larvae) and Phytoseiidae were noted.

scholarly journals SYNTHESIS AND RESEARCH OF NITROGEN-CONTAINING XANTHANE GUM DERIVATIVES

2020 ◽  
Vol 9 (5(74)) ◽  
pp. 57-62
Author(s):  
O.R. Ahmedov ◽  
N.Sh. Rahmatova ◽  
H.S. Talipova ◽  
Z.S. Alihonova ◽  
A.S. Turaev
Keyword(s):  
Xanthan Gum ◽  
Condensation Reaction ◽  
Oxidation States ◽  
Reaction Products ◽  
Scanning Calorimetry ◽  
Quantitative Content ◽  
Degree Of Oxidation ◽  
Physicochemical Methods ◽  
Aldehyde Groups ◽  
Derivatives Of

This study presents the results concerning the synthesis of nitrogen-containing derivatives of xanthan gum. The authors obtained xanthan gum derivatives with various oxidation states through the preliminary reaction of periodic oxidation of the polysaccharide. Through the physicochemical methods of analysis, the structure and established quantitative content of aldehyde groups in the macromolecular chain of the polysaccharide were proved. It was possible to carry out a condensation reaction with guanidine and to synthesize new macromolecular derivatives in the presence of reactive aldehyde groups in the structure of xanthan gum. The synthesized derivatives were further investigated through IR spectroscopy, thermogravimetry, differential scanning calorimetry, and elemental analysis for nitrogen content. Furthermore, it is found that the amount of guanidine and the degree of substitution in the synthesized compounds are 15.3-39.0% and 34-85 mol.%. Finally, when using modified xanthan gum with a different degree of oxidation it is possible to vary the quantitative content of guanidine and the degree ofsubstitution in the reaction products.

scholarly journals Unveiling Extreme Photoreduction Potentials of Donor-Acceptor Cyanoarenes to Access Aryl Radicals from Aryl Chlorides

2021 ◽  
Author(s):  
Jinhui Xu ◽  
Jilei Cao ◽  
Xiangyang Wu ◽  
Han Wang ◽  
Xiaona Yang ◽  
...  
Keyword(s):  
Limited Range ◽  
Redox Potentials ◽  
Aryl Chlorides ◽  
Aryl Radicals ◽  
Reduction Potentials ◽  
Anion Form ◽  
Donor Acceptor ◽  
High Reduction ◽  
Very High ◽  
Excited Radical

Since the seminal work of Zhang in 2016, donor-acceptor cyanoarene-based fluorophores, such as 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), have been widely applied in photoredox catalysis, and used as excellent metal-free alternatives to noble metal Ir- and Ru-based photocatalysts. However, all the reported photoredox reactions involving this chromophore family are based on harnessing the energy from a single visible light photon, with a limited range of redox potentials from -1.92 V to +1.79 V. Here, we document the unprecedented discovery that this family of fluorophores can undergo consecutive photoinduced electron transfer (ConPET) to achieve very high reduction potentials. One of the newly synthesized catalysts, 2,4,5-tri(9H-carbazol-9-yl)-6-(ethyl(phenyl)amino)isophthalonitrile (3CzEPAIPN), possesses a long-lived (12.95 ns) excited radical anion form, 3CzEPAIPN<sup>•</sup><sup>−</sup>*, which can be used to activate reductively recalcitrant aryl chlorides (E<sub>red </sub>≈ -1.9 to -2.9 V) under mild conditions. The resultant aryl radicals can be engaged in synthetically valuable aromatic C-B, C-P, and C-C bond formation to furnish arylboronates, arylphosphonium salts, arylphosphonates, and spirocyclic cyclohexadienes, respectively.

CYTOCHROME OXIDASE ACTIVITY OF CELL NUCLEI

1954 ◽  
Vol 32 (1) ◽  
pp. 548-552 ◽  
Author(s):  
David Rubinstein ◽  
Orville F. Denstedt
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Oxidase Activity ◽  
Nuclear Material ◽  
Liver Cells ◽  
Nuclear Fraction ◽  
Cell Nuclei ◽  
Nuclear Membranes ◽  
Rat Liver Cells ◽  
Chicken Erythrocytes

The presence of cytochrome oxidase in the nuclear material from chicken erythrocytes and rat-liver cells has been demonstrated with the aid of p-phenylenediamine as the agent for reducing cytochrome c. The three reagents p-phenylenediamine, ascorbate, and hydroquinone are effective in the estimation of cytochrome oxidase in mitochondrial preparations, but only the first mentioned agent can effect the reduction of endogenous cytochrome c. The addition of cytochrome c will increase the oxidase activity of the liver-cell mitochondria but not of the nuclear fraction from the erythrocytes or the liver cells, presumably because of the impermeability of the nuclear membranes to added cytochrome c.

The Histochemical Demonstration of Keratin by Methods involving Selective Oxidation

1951 ◽  
Vol s3-92 (20) ◽  
pp. 393-402
Author(s):  
A. G. EVERSON PEARSE
Keyword(s):  
Periodic Acid ◽  
Cobalt Nitrate ◽  
Histochemical Demonstration ◽  
Performic Acid ◽  
Cysteic Acid ◽  
Acid Oxidation ◽  
Reaction Products ◽  
Periodic Acid Schiff ◽  
Periodic Acid Oxidation ◽  
Schiff Reaction

1. Oxidation of tissues with performic acid gives rise to histochemically detectable reaction products particularly in two classes of material. These are keratin and lipoids of the phosphatide class. 2. Three methods have been evolved for visualizing the effect of performic acid on cystine-containing structures; two of these (performic acid/Schiff and perfoiTnic acid/cobalt nitrate) also record the effect on lipoids. 3. An attempt has been made to elucidate the chemistry of the reactions and it is suggested that oxidation of cystine in the tissues gives rise not only to cysteic acid (alanine-beta-sulphonic) but to another acid (alanine-beta-sulphinic). The latter is responsible for the positive reaction with Schiff's solution. 4. The Schiff reaction with performic acid oxidized lipoids is due to the formation of substances giving the reactions of aldehydes. It is possible that similar groups may be produced from lipoid molecules by periodic acid oxidation and that these and not polysaccharides (1.2 glycols) are responsible for the periodic acid-Schiff reaction in such cases.

scholarly journals Identification of Escherichia coli YgaF as an l-2-Hydroxyglutarate Oxidase

2008 ◽  
Vol 190 (11) ◽  
pp. 3793-3798 ◽  
Author(s):  
Efthalia Kalliri ◽  
Scott B. Mulrooney ◽  
Robert P. Hausinger
Keyword(s):  
Escherichia Coli ◽  
Unknown Function ◽  
Oxidase Activity ◽  
Flavin Adenine Dinucleotide ◽  
Reduction Potential ◽  
High Reduction ◽  
Very High

ABSTRACT YgaF, a protein of previously unknown function in Escherichia coli, was shown to possess noncovalently bound flavin adenine dinucleotide and to exhibit l-2-hydroxyglutarate oxidase activity. The inability of anaerobic, reduced enzyme to reverse the reaction by reducing the product α-ketoglutaric acid is explained by the very high reduction potential (+19 mV) of the bound cofactor. The likely role of this enzyme in the cell is to recover α-ketoglutarate mistakenly reduced by other enzymes or formed during growth on propionate. On the basis of the identified function, we propose that this gene be renamed lhgO.

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