Biomedical subjects

T I Tikhonenko

Publications and source records attributed to T I Tikhonenko.

At least 91 records · Page 5Linked to original sources

PubMedDate not supplied

[Liberation of DNA from particles of CD phage of DNA-protein complex: Properties of DNA in the complex and the effect of formaldehyde on the complex structure].

Properties of DNA in a complex with protein, which was liberated after destruction of CD phage by heat treatment in solutions with low ionic strength, were studied. DNA in the complex did not differ from free DNA under the same conditions as shown by spectra of circular dichroism and by the type of melting during the thermic denaturation. As demonstrated by viscosimetry and gradient centrifugation in cesium sulfate, 1.5% formaldehyde inhibited the dissociation of the complex studied in a medium containing 0.15 M NaCl. In the medium with 1.5% of HCHO T degrees ml of DNA in the complex was distinctly higher than T degrees ml of free DNA under the same conditions. Electron microscopy showed that the complex studied comprised DNA ;molecules, associated with protein membrane in one or several internal sites.

Bacteriophages↗

PubMedDate not supplied

[Inactivating effect of o-methylhydroxylamine on phage lambda and its mutants].

The kinetics of inactivation of lambda+, lambda C160, lambda Nsus7, lambda Gsus9, lambda Tsus6 phages under the effect of O-methylhydroxylamine was studied. Inactivation curves of all the phages under study were found to be of a complex character and early in the reaction (up to 4 hours) to deviate from exponential dependence of the inactivation rate upon the time of incubation with the mutagen. All the phages under study showed differences in the inactivation rates early in the reaction. Constants of the inactivation rate in the linear part of the curve vary from 30 hours-1 for lambda+ to 0.14 hours-1 for lambda C160. The possible causes of the complicated pattern of inactivation courves of lambda phage and its mutants are discussed.

Coliphages↗

PubMedDate not supplied

[Fungal origin of PBV-group viruses isolated from Penicillium brevi-compactum].

Treatment of extracts from the disintegrated mycelium of Penicillium brevi-compactum with antisera against viruses PBV-1 and PBV-3 grown on bacteria results in a considerable decrease in the infectiveness of micellar preparations toward E. coli C. This is a specific reaction since treatment with a heterologic antiserum against phage T2 has no effect on the infectiveness of the micellar extracts. The kinetics of reassociation of DNA from PBV-3 and DNA from Penicillium brevi-compactum has shown that the value of Cot at half-reassociation of these DNAs is 13.3 times higher than the value of Cot at half-reassociation of DNA from PBV-3 and heterologic DNA from chicken embryos. As was found by calculations, DNA isolated from the fungal mycelium contains virus sequences at an amount of 3.7 virus genomes per cell. These data confirm the micellar origin of the viruses PBV-1 and PBV-3. The virus PBV-3 is supposed to be present in the cells in the form of prophage.

Bacteriolysis↗

PubMedDate not supplied

[Release of DNA from Sd phage in a protein complex].

The properties of DNA released from Cd phage upon destruction of virions by heating in solutions of low strength were studied. The viscosity of DNA released from the phage after heating in 0.01 X SSC (SSC-0.15 M NaCl divided by 0.015 M sodium citrate, pH 7.0) was found to be no more than 40% of that of DNA released from the phage destroyed by heating in 1 X SSC. Addition of salts up to 1 X SSC to the phage destroyed by heatings in 0.01 X SSC resulted in a marked increase of the viscosity of the latter. According to the results of centrifugation in cesium sulphate and sucrose density gradients, upon phage destruction by heating in 0.01 X SSC DNA war released from virions in the form of a complex with protein. Addition of NaCl up to 1 X SSC to the phage preparations destroyed in the low ionic strength solution led to destruction of this complex. The complex under study was not formed in dialysis against 0.01 X SSC of phage preparations destroyed in 1 X SSC.

Centrifugation, Density Gradient↗

PubMedDate not supplied

[Analysis of the nucleotide sequence of a fragment (92-100%) of the CELO avian adenovirus genome].

The nucleotide sequence of 92-100% of the adenovirus CELO (FAV1), strain Phelps, genome has been determined. The computer analysis of the sequences revealed a ClaI site methylated by m*Ecodam. A recognition site for XbaI and two sites for PstI, not found in the corresponding genome of CELO, strain Ote, have been determined. Three extensive (more than 100 amino acid residues) open reading frames exist, coding for the polypeptides with molecular weights of 31.5, 19.3 and 14.5 kD (276, 178 and 128 amino acids, respectively). Some shorter open reading frames have been detected as well within the sequences studied.

Amino Acid Sequence↗

PubMedDate not supplied

[Structural and immunochemical analysis of the products of proteolysis of simian adenovirus hexons].

Hexon capsomers of simian adenovirus sim16 (SA7) and of human adenoviruses h5 (Ad5) and h6 (Ad6) were proteolytically digested and the resulting products studied by SDS-polyacrylamide gel electrophoresis and by radioimmunoprecipitation analysis. The trypsinolysis of native SA7 hexon leads to a stable molecular "core" containing 4-5 fragment species of 10 to 65 kDa and resembling the intact capsomer in quarternary structure (trimer). Similar cores but consisting of smaller fragments (less than 40 kDa) were obtained after chymotryptic digestion of native SA7, Ad5 and Ad6 hexons. The chymotryptic hexon fragments were also held together in pseudotrimeric structures. The similarity of proteolytic hexon fragment patterns between different primate adenoviral hexons suggested a homology to exist in localisation of the exposed tryptic and chymotryptic cleavage sites in their respective hexon polypeptide chains. Papain caused a complete hydrolysis of native SA7 hexon (trimer) yielding small peptides, but at first stage of digestion a stable papain hexon core containing small fragments (less than 10 kDa) was observed. The tryptic SA7 hexon cores in native state retained their antigenicity in reactions with homo- and heterologous antibodies, but after core denaturation the resulting fragments had no antigenic activity of native capsomer. In contrast to the data previously published, chymotryptic cores of SA7, Ad5 and Ad6 hexons not only reacted with respective homologous antibodies but also retained (at least in part) cross-reactive antigenic determinants. The questions of formation and stability of native adenoviral hexon conformation are discussed as well as the possible nature of hexon antigenic determinants.

Adenoviridae↗

PubMedDate not supplied

[Antisense polynucleotides and prospects for their use in fighting viruses].

Natural or synthetic anti-sense (as) polynucleotides complementary to distinct functional regions of mRNA (asRNA or asDNA) are able to inhibit the expression of any target gene. If certain viral mRNAs important for virus replication are targeted the inhibition of viral infection by asRNA or asDNA takes place. Inhibitory effects of complementary polynucleotides on gene activity in eukaryotic cells is due to the disturbance of translation of corresponding mRNAs as well as to the impairment of their splicing or transportation from the nuclei to cytoplasm. In prokaryotic cells, obviously, only the first factor is operating. The recombinant genes programming anti-viral asRNA can confer the resistance to the infection by other virus to the transformed cells. The resistance to viral infection observed in transgenic animals, expressing asRNA genes, may be considered as a new unnatural form of informational immunity.

Base Sequence↗

PubMedDate not supplied

[Biological effects accompanying the microinjection of adenovirions, adenoviral and plasmid DNA into mammalian cells].

Microinjection of either type 1 human adenovirus, type SA7 monkey adenovirus virions or circular adenovirus DNA, obtained by the treatment of DNA-terminal protein complexes with glutaraldehyde, into nuclei of permissive cells results in the complete cycle of virus reproduction. Microinjection of neither linear native, condensed adenovirus DNA nor the DNA-terminal protein complexes under the same conditions initiates the adenovirus reproduction thought the synthesis of early and some late viral antigens is observed in the injected cells. Integration of injected adenovirus DNA into the cellular DNA occurs as far as 30 min after injection. Microinjection of either adenovirus DNA or its oncogene containing fragments into nuclei of semipermissive cells induces the transformation of these cells. In this case the time of the first appearance of transformation foci is decreased.

Adenoviridae↗

PubMedDate not supplied

[Splitting and rejoining simian adenovirus type 7 DNA by using Eco RI restriction endonuclease and DNA-ligase].

Optimal conditions for ligation of simian adenovirus type 7 (SA-7) DNA fragments formed under the effect of treatment of the intact molecule with Eco RI endonuclease were established. It was shown that up to 30% of the original material may be ligated and transferred into a structure with molecular weight 23 X 10(6) daltons which corresponded to the molecular weight of the intact SA-7 DNA. The data of the existence of one recognition site for Eco RI in SA-7 DNA were confirmed. The biological activity of the ligated material was demonstrated on lambda-III phage DNA.

Adenoviridae↗

PubMedDate not supplied

[Possible mechanisms of the transforming and tumorigenic effects of DNA-containing animal viruses].

The literature devoted to oncogenic action of DNA-containing animal viruses and their role in the development of human neoplasias are reviewed. The regularities of persistence and expression of genetic material of DNA-containing viruses in transformed and tumor cells are comprehensively analyzed. The mechanisms of recombination of cellular and viral DNA during cell transformation as well as the specificity of integration of viral DNA into the host genome are considered. The functions and mechanisms of transforming and tumorigenic action of the products of oncogens of DNA-containing viruses of different groups are discussed. The data on the cell transformation by some DNA-containing viruses without oncogene expression are represented. The mechanism of cell transformation by DNA-containing viruses related to the activation of cellular oncogens is discussed.

Adenoviridae↗

PubMedDate not supplied