Physicoсhemical Characteristics and Sorption Capacity of Biosynthetic Polymers Based on Ferulic Acid and Coniferyl Alcohol with Respect to the Zearalenone Mycotoxin

Russian Journal of Bioorganic Chemistry - The data on the chemical structure of the polymers, synthesized by the method of fermentative dehydropolymerization of ferulic acid, as well as coniferyl...     

Electron microscopic study of compactization of individual DNA molecules in films during the interaction with histone H1]

The protein-free method was applied for the investigation of histone H1 DNA complexes formation. The main advantage of this method is the possibility to get intramolecular compact structures at interaction of individual spread molecules of DNA with histone H1. It was shown that in the presence of 0.2-5 micrograms/ml of histone H1 in hypophase there are three types of structures on electronmicroscopic preparations: fibres of non-compacted DNA, compact fibres with twisted strands of duplex DNA and compacted rod-like and circular structures where separate fibres of duplex DNA could not be distinguished. The study of compact structures morphology allows to conclude that they are formed by side-by-side association of DNA fibres, as it takes place in the case of triple rings formation at the compactization of circular DNA due to trivaline binding. At increasing ionic strength there is a tendency for transition from second type structures to the third type structures. The latter can be explained by transition from non-cooperative to cooperative binding of histone H1 to DNA.     

Peroxidase and laccase as catalysts for removal of the phenylhydrazide protecting group under mild conditions

A new method is proposed for the removal of the phenylhydrazide protecting group by the action of peroxidase or laccase, the enzymes attributed to the class of oxidoreductases. The deblocking procedure is performed under mild oxidative conditions, i.e., aqueous solution and neutral or close to neutral pH. Such mild oxidizing agents as 1 mM H(2)O(2) and air oxygen are used for unmasking. The method is available for the deblocking of both alpha- and gamma-carboxyl groups. The enzyme-catalyzed removal of the phenylhydrazide protecting group causes no oxidative modification nor destruction of methionine or tryptophan side chains. (c) 1993 John Wiley & Sons, Inc.     

Hyphenated thermal field flow fractionation--capillary electrophoresis

The possibility was considered to use the transverse thermophoresis of analytes in the capillary for capillary electrophoresis (CE) to control the separation process, decrease the peak width due to thermal effects and provide new separation parameters in CE. As the examination has shown, in non-aqueous buffers the Joule heating in the capillary for CE can provide transverse temperature gradients comparable with the temperature gradients in conventional devices for thermal field flow Fractionation (ThFFF). It was proposed to use the non-uniform velocity profile of analytes caused by the transverse temperature gradient and the temperature dependence of the buffer viscosity for the FFF-like separation of analytes besides CE separation. The expressions for the peak parameters have been derived, where the non-uniform transverse analyte concentration distribution due to the thermophoresis is taken into account, and the possibilities based on FFF-CE principles are discussed. As possible objects of this hyphenated technique, macromolecules and particles are considered.     

The effect of cobalt on the dynamics of membrane-bound calcium in the cerebral cortex structures

Cobalt (Co2+) influence on calcium bound (Cab2+) dynamics detected by a fluorescent chlorotetracyclin probe (CTC), as well as bioelectric activity were studied in the feline vital brain cortex preparation with contact microscopy and microelectrode technique. It has been found that Co2+ applied on the preparation surface or injected ionophoretically into microzones under microscopy produced a distinct decrease of CTC-Cab2+ fluorescence intensity. This indicates a decrease of Cab2+ content in the hydrophobic membrane loci. The effect is reversible and depends on Co2+ concentration. Neuronal excitation appeared after the fluorescence decrease up to 5-12% to the start level. It has been concluded that Cab2+ content dynamics plays an important role in the Co2+ "seizure" discharges mechanisms in the cortex.     

Intramolecular compactization of circular DNA in interaction with dansyl hydrazide trivaline leading to a formation of a new type of structure--triple rings

Compactization of supercoiled circular plasmid pBR322 caused by interaction with synthetic oligopeptide dansyl hydrazide trivaline capable of beta-structure formation was studied by electron microscopy. The results show that at rising input peptide concentration circular DNA molecules undergo intramolecular structural transition with the formation of compact ring structures. The compact ring structures are formed by the fiber having the thickness of 60 A. The analysis of morphology of intermediate structures and the contour length measurements enable us to conclude that 60 A-fiber contains three lying side-by-side and interwound double-stranded DNA segments. Thus, the compact ring structures are addressed to as triple rings. The triple ring have one special point, where the triple region ends are locked by a duplex DNA segment. The mechanisms responsible for the triple ring formation may be of importance for DNA and chromatin compactization processes in vivo.     

Mutagenic effect of chemical compounds on laboratory mice]

Mutagenic effect of thioTEPA applied at a dose of 1.25 mg/kg was studied in late spermatids of C57BL/L male mice. The mutagen induced dominant lethal mutations in germ cells (39%) and symmetric translocations in 33.5% of F1 male offspring. The common frequency of sperms with chromosome mutations was 60%, that is ten times as much as the mutagenic effect in bone marrow cells. 39% of embryos at 3.5 days of development died or delayed their development at 2--22 blastomers stages. Structure chromosome aberrations were found in the cells of such embryos. The scheme of genetical screening of chemical compounds in laboratory mice, based on the data obtained early and in the present experiment, is proposed.     

Effect of ethylenediaminetetraacetic acid on the synapsis of polytene chromosome homologs and "supplementary nucleolus formation"]

On being added to the food of larvae of Drosophila melanogaster of various age, EDTA, within a broad scale of concentrations, does not change the frequency of asynapsis of polytene homologues. The "many nucleoli" phenomenon was observed both after EDTA treatment and without it. The frequency of this phenomenon is thought to depend on the conditions of slide preparation. Therefore many nucleoli may be probably fragments of general nucleoli.