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V I Vorob'ev

Publications and source records attributed to V I Vorob'ev.

At least 19 recordsLinked to original sources
PubMed1995

[Conformational features of linker proteins of supercompact chromatin from marine invertebrate sperm].

A comparison of conformational potencies of linker histones of the H1 family has been performed by the curcular dichroism (CD) method. The histones were isolated from sera urchin (Strongylocentrotus intermedius), starfish (Aphelasterias japonica) and mollusc (Chlamis islandicus) sperm and rat thymus. The presence of an additional alpha-helical segment in the C-terminal part of the H1 histone from sea urchin sperm has been found to be a characteristic peculiarity of echinoderm sperm linker histones H1. The conformational properties of the H1 from starfish and sea urchin sperm are similar. The terminal domain of the mollusc sperm H1 has a more stable conformation of the left-handed helix in comparison with histones H1 of a different origin. It has been shown that the terminal fragments of the tested histones play an essential role in thermal stabilization of the secondary and ternary structures of the globular domains in these histones. The results obtained point to the difference in the mechanisms of supercondensed organization of sperm chromatin. The role of H1 histones in this process is discussed.

Animals↗
PubMed1994

Disturbances of nuclear condensation in human spermatozoa: search for mutations in the genes for protamine 1, protamine 2 and transition protein 1.

During spermiogenesis, the successive replacement of the somatic histones by basic proteins, the transition proteins and protamines, allows normal sperm nuclear condensation. It was suggested that disturbances in nuclear condensation may result in male infertility. Here we report the first molecular analysis of the structure of three genes which code for germ cell-specific nuclear proteins, namely protamine 1 (PRM1), protamine 2 (PRM2) and transition protein 1 (TNP1) in infertile men with disturbed sperm chromatin condensation. In 36 infertile men whose spermatozoa showed a positive reaction with aniline blue, which is an indication for the presence of histones in the nuclei, the complete nucleotide sequences of the coding regions and 5' and 3' untranslated regions of the three genes were evaluated. In addition, 10 infertile patients with oligoasthenoteratozoospermia were studied in the same way, as well as nine infertile patients whose spermatozoa showed a reduction of the protamine 2 content. We did not detect any mutation in the three genes in any of the patients. We assume that the disturbances in the sperm chromatin condensation of our patients, and those described in the literature, are not primarily due to mutations in the genes for PRM1, PRM2 and TNP1.

Base Sequence↗
PubMed1993

Human male infertility may be due to a decrease of the protamine P2 content in sperm chromatin.

Basic chromosomal proteins were extracted from the sperm of fertile and infertile human males. The relative proportions of protamine 1, 2, and 3 were determined by scanning microdensitometry following electrophoresis of total protamine in polyacrylamide gels. The findings were as follows: (1) The proportion of protamine P(2 + 3) in sperm obtained from infertile males was lower than that in fertile males. (2) Protamine P(2 + 3) in infertile human males showed reduced affinity to DNA. The possibility that some cases of human male infertility may be due to mutation within the protamine P2 gene is discussed.

Chromatin↗
PubMed1993

[DNA-dependent RNA-polymerase II from human placental nuclei].

The procedure for isolation and purification of RNA polymerase II from human placenta nuclei is described. The sensitivity of the enzyme to alpha-amanitin, bivalent cations, ionic strength and glycerol concentration in vitro has been studied. Eleven subunits of the RNA polymerase II molecule have been identified by gel electrophoresis. An optimal RNA polymerase II assay mixture has been developed.

Cell Nucleus↗
PubMed1993

[Features of structural organization of chromatin from various sources].

The conformational peculiarities of DNA and histones of chromatins of different origin have been studied using circular dichroism (CD). The chromatins were isolated from pigeon brain, rat thymus and liver, ascitic hepatoma 22A, C3HA mouse liver, pigeon erythrocytes and sea urchin sperm. The functional peculiarities of the chromatins were found to correlate with their compactness and the nucleosomal DNA repeat length. Analysis of chromatin CD spectra made it possible to define the degree of DNA compactness in oligonucleosomes and the secondary structure of their linker histones of the H1 family. It was found that in low ionic strength solutions the structures of chromatosomes are formed in erythrocyte and thymus chromatins, but not in sea urchin sperm chromatin. The size of the compact part of the DNA in the nucleosomes of transcriptionally active chromatins of brain and ascitic hepatoma 22A are less than the length of the DNA of the core particles under identical conditions. The secondary structure of the H1 histone from sea urchin sperm chromatin, unlike other linker histones of the H1 family, contains an additional alpha-helical segment in the C-terminal part. Analysis of structural changes of the both chromatin components during condensation of their oligonucleosomal chains with an increase in the ionic strength has been carried out.

Animals↗
PubMed1993

[Human male sterility can be caused by mutations in the protamine P2 gene].

The sperm of fertile and infertile human males was treated with 0.25 n. HCl or 1% CTAB. Relative proportions of various protamine fractions in the obtained extracts were determined by scanning microdensitometry following electrophoresis of the total protamine in polyacrilamide gels. The findings were as follow. 1. The share of protamine P(2 + 3) in the sperm obtained from infertile males was lower than that of fertile males. 2. Protamine P2 in infertile males has a reduced affinity to DNA. It is suggested that in some cases the human male infertility may be due to some mutations within the P2 gene.

Cell Count↗
PubMed1990

Chromatin higher-order structure: two-start double superhelix formed by zig-zag shaped nucleosome chain with folded linker DNA.

Hydrodynamic properties of chromatins differing in linker DNA length and in transcriptional activity have been studied by the method of sedimentation velocity. Oligonucleosomes of different chain length were isolated from chromatins of pigeon brain cortical neurones, rat thymus and sea urchin sperm characterized by nucleosome DNA repeat length of 165, 198 and 248 base pairs respectively. The hydrodynamic behaviour of oligonucleosomes in the dependence on the number of nucleosomes in the chain and on the ionic strength has been analysed on the basis of cylinder model. The data obtained allows one to calculate the main structural parameters of the oligonucleosomal chain: its mass per unit length, the hydrodynamic diameter of the chain, the length of the chain per nucleosome and DNA packing ratio. It is shown that hydrodynamic behaviour of nucleosome oligomers from all types of chromatins investigated at low ionic strength can be well described by the model of three-dimensional zig-zag chain with similar diameter and length of the chain per nucleosome, DNA packing ratio growing with the increase of linker DNA length. It can be achieved by unfolding the short linker DNA in neurone chromatin and by coiling the long linker DNA of sea urchin sperm chromatin into a loop. With the increase of ionic strength zig-zag shaped nucleosomal chain is condensed into a two-start double superhelix with closely arranged nucleosomes and linker DNA loops packed inside the superhelix. The suggested model is in good agreement with available experimental data and overcomes a number of difficulties which arise for the solenoid model and other models of the 30-nm chromatin fibril.

Animals↗
PubMed1989

Structural differences between histone H1 molecules from sea urchin (Strongylocentrotus intermedius) sperm and calf thymus: hydrodynamic and c.d. studies.

Comparative sedimentation, diffusion and circular dichroism (c.d.) measurements have been performed on two histones H1 from sperm of the sea urchin Strongylocentrotus intermedius (H1S) and from calf thymus (H1T), at a high salt concentration of M NaCl. Both the Stokes radius and the frictional ratio derived from the hydrodynamic parameters were found to be somewhat smaller for H1S than the corresponding values for H1T. In view of the considerably higher molar mass of H1S compared with that of H1T, this result indicates that H+S in 2 M NaCl has a more compact conformation than H1T, probably due to a higher degree of secondary structure in the flanking domains of H1S. The c.d. measurements likewise show that H1S has a higher content of ordered structures than H1T. Model considerations indicate that the C-terminal tail of H1S is the main candidate for accommodation of these additional secondary structure regions.

Animals↗
PubMed1984

Cortisone-induced small RNP tightly bound to chromatin.

The small nuclear RNP (alpha-RNP) tightly bound to chromatin has been isolated. alpha-RNP can be removed from chromatin together with the acid-soluble proteins. The RNA from this RNP has been isolated; its electrophoretic mobility is equal to that of 4 S RNA. The study of the resistance of alpha-RNA to RNases (A, T1 and S1) in salt solutions of various ionic strengths allows us to conclude that the alpha-RNA has a well-developed secondary structure. The alpha-RNA is tightly associated with the protein moiety of alpha-RNP and has developed secondary structure. The alpha-RNA is tightly associated with the protein moiety of alpha-RNP and has a high metabolic activity.

Animals↗
PubMed1983

[Dysbacteriosis].

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Bacterial Infections↗
PubMed1982

The role of histone H2B from sea urchin sperm in the association of reconstituted minichromosomes.

A comparative study of the condensation of reconstituted complexes of circular SV40 DNA with core histones from calf thymus and sea urchin sperm was performed using sedimentation and electron microscopic techniques. It is shown that in low ionic strength solutions both types of complexes are similar to native 'minichromosomes'. In the region from 0.08 to 0.16 M NaCl the complexes of SV40 DNA with thymus histones form small compact particles. By contrast, the compaction of the SV40 DNA complexes with sperm histones results in the formation of giant intermolecular associates. The results obtained may mean that histone H2B of sea urchin sperm participates in the formation of a higher order structure in sperm chromatin.

Animals↗