[Genetically programmed cell death (apoptosis)]. / Geneticheski programmirovannaia smert' kletok (apoptoz).

Extensively and successfully studied problems of programmed cell death are considered. Recent evidence on apoptosis genes is presented, including the bcl-2 family and other genes with similar functions. A scheme of pathways of the main apoptosis mechanism is constructed. Examples of associations of apoptosis and diseases are presented in a special section.

[Strategy of production and utilization of immortal cells]. / Strategiia polucheniia i ispol'zovaniia immortal'nykh kletok.

The current methods of production of conditionally immortal cells in vivo and in vitro have been considered, including the method based on transgenesis of animals. Examples are given for utilization of conditionally immortal cells obtained in vivo from tissues of transgenic mice and rats carrying the gene of mutant T-antigen tsA58 SV40. The recent studies were analyzed, which concern the investigation and utilization of embryonic and regional stem cells, as well as immortal cells obtained through transfection of the recombinant construct of telomerase gene into human cells. The main problems of cell biotechnology are discussed.

[Single-stranded DNA from viruses, prokaryotes and eukaryotes]. / Odnotsepochechnye DNK virusov, prokariot i éukariot.

The review presents the results of investigations of single-stranded DNAs of viruses, bacteria and cells of higher organisms. Methods of revealing, isolating and analysis of these DNAs are presented. A large variety of single-stranded DNA containing genomes of plant and animal viruses was revealed. Attention is drawn to the integration and replication of viral genomes. Results of SV40 integration during the first two days after infection of Chinese hamster cells are shown. Results of studying multi-copy single-stranded DNA in bacterial cells were analysed. In separate sections, the replication of plasmid single-stranded DNA was studied as well as the problem of plasmid stability in cells. Advances in bacteria transformation studies are stated. Data of single-stranded DNA investigation in cells of higher organisms are mainly presented on the example of early embryos. Data on the analysis of gene hypersensitivity to nuclease S1 are given. A table of proteins destabilizing and unweaving single-stranded DNA and a classification table of proteins bound with single-stranded DNA according to their functional significance are presented. It is stated that the problem of single-stranded DNA significance in cells remains open, although some results have been achieved.

[Molecular mechanisms of regulating mammalian sex and problems of fractionating spermatozoa]. / Molekuliarnye mekhanizmy reguliatsii pola u mlekopitaiushchikh i problema fraktsionirovaniia spermatoidov.

We present results of a study devoted to genetic determination and to the mechanism of primary sex differentiation in mammals. Progress is achieved in the mapping of a Y chromosome region necessary and sufficient for testis determination in man (TDF) and mouse (Tdy). We discuss a possible role in sex regulation of a recently described highly conservative locus from this region, ZFY (and similar loci within other chromosomes probably coding for Zn-binding proteins, transcription regulators) and H-Y antigen as well. We note that neither locus ZFY nor H-Y can play the role of TDF (Tdy) and that studies in this direction should be carried out. Numerous works on fractioning according to sex of spermatozoa of mammals including man are critically reviewed. Contradictory data exist in literature concerning the applicability of different approaches for this purpose: from fractioning based on different inherent mobility of different sex cells or gel-filtration, to the sorting in a flow cytometer equipped with a laser light source and a computer. However, in many cases the principle underlying this or that method of fractionation and determining the positive results, i.e. the statistically important shift of the sex ratio as compared with the initial sperm, remains unclear. It is stated that on the immunological and electrophoretic approaches might appear most promising for practical application, and in cattle-breeding as well. Modern procedures for sex testing and the fertility control of spermatozoa are also examined.

[The role of single-stranded DNA in the integration of SV40 genome into cellular DNA]. / Issledovanie uchastiia odnonitevoi DNK v integratsii genoma SV40 c DNK kletok.

The integration of temperature-sensitive SV40 mutant DNA (tsA239) into the Chinese hamster cellular genome at an early stage of infection was studied. The content of single-stranded DNA structures in the infected and control cells at a non-permissive temperature (40 degrees C) differed drastically from that in control cells at permissive temperatures (33 degrees C, 37 degrees C). The role of single-stranded structures in the integration of the SV40 genome into cellular DNA was shown by blot hybridization. The integration mechanism is discussed.

[Integration of SV40 DNA into the cell genome and viral mutagenesis]. / Integratsiia DNK SV40 v genom kletok i virusnyi mutagenez.

Integration of DNA of a temperature-sensitive SV40 mutant (tsA239) into the cell genome was studied. The viral A gene (the oncogene) encodes the tumour T antigen which is ts in the mutant and is devoid of mutagenic and transforming activity under non-permissive conditions (40 degrees C). Clones of Chinese hamster cells infected by tsA239 mutant were analysed. Those infected by wild-type SV40 served as controls. As shown by dot-hybridization, SV40 DNA was detected in cells of 14 out of 18 clones infected by tsA mutant and incubated at 40.5 degrees C, and in all 20 clones infected by tsA mutant and incubated under permissive conditions (33 degrees C), the difference between the two groups being insignificant (p greater than 0.05). By means of blot-hybridization it was established that viral DNA was integrated into the cell genome of all 12 clones analysed, belonging to the three experimental series: infection by tsA mutant, incubation at 40.5 and 33 degrees C, infection by wt SV40, incubation at 40.5 degrees C. The number of integration sites ranged from one to four in different clones. Integration of SV40 DNA in tandems was observed. The data presented allow to conclude that integration per se does not play a crucial role in determining the mutagenic and transforming effect of the virus. Obviously, what matters is the activity of viral oncogene product - the T antigen.

Microinjection of simian adenovirus SA7 (C-8) DNA into the mouse zygotes: differential distribution of viral DNA in organs.

A simian adenovirus SA7 (C-8) DNA was microinjected into fertilized mouse eggs. Thirty-five mice derived from eggs injected with SA7 DNA were screened for the presence of the adenovirus genome in their liver DNA. Eighteen of these mice contained the virus-specific sequences. SA7 DNA was detected in some tissues, but in all cases, viral sequences were absent from muscle and heart DNA. Viral DNA was inherited by 50-70% of the next generation. One mouse that contained about 1 copy of SA7 DNA per haploid genome has been shown to pass it on to five generations, although the integrated viral DNA sustained a considerable structural change between F1 and F3. RNA analysis in various organs of 12 mice has shown the transcription of SA7 DNA to be very infrequent: only in the kidney of one mouse and in the spleen of another did RNA contain SA7-specific sequences.

[Nucleotide sequence organization of nuclear DNA of wheat embryos]. / Organizatsiia nukleotidnykh posledovatel'nostei iadernoi DNK zarodyshei pshenitsy.

The kinetic component composition of wheat embryo nuclear DNA was studied. It was shown that 32% of the genome consist of highly repetitive sequences. Intermediate repetitive sequences with repetitive frequency 1300 per genome constitute the bulk (52%) of the wheat embryo nuclear genome. The unique sequences constitute 12% of wheat embryo DNA. The individual families of intermediate repetitive and unique sequences were isolated; their reassociation kinetics were investigated and their kinetic complexity and repetition frequency were evaluated. Intermediate repetitive sequences 600-800 nucleotides in length were interspersed with unique sequences 800-1000 nucleotides long in the nuclear genome of wheat embryos. The linear relationship between the fragment length and the increasing amount of the zero-time binding DNA implies that 4% of the wheat embryos genome consists of palindromic sequences, which are clustered into groups.

[Size and organization of repetitive sequences in pigeon genome]. / Razmer i organizatsiia povtoriaiushchikhsia posledovatel'nostei v genome golubia.

Organization of sequences in pigeon genome and the spectrum of their repetition frequencies were studied by means of DNA/DNA reassociation. Reassociation of 125I-labelled DNA fractions isolated from pigeon total DNA attested the presence of rare repetitions with an average of 50 copies within a gaploid genome. The disposition of repetitive and unique sequences was studied by reassociation of the labelled fragments of different length with an essential excess of short fragments of an unlabelled DNA. Additional evidence was provided by estimation of hyperchromicity and resistance to nuclease S1 of long DNA fragments, reassociated to the given C0t values. It was demonstrated that approximately one fourth of the pigeon genome consists of intermittent repetitive and unique sequences with individual elements of average length of 2 and 37 kb, respectively (1 kb = = 1000 nucleotide base pairs). A hypothetical organization of palindromic sequences in pigeon genome is discussed in terms of the dependence of the value of zero binding to hydroxyapatite on the fragment length.

[Fractionation of DNA containing single-stranded regions on a column with benzoylated DEAE-cellulose]. / Fraktsionirovanie DNK, soderzhashchikh odnonitevye uchastki, na kolonke s benzoilirovannoi DEAE-tselliulozoi.

A possible use of a previously described method of fractionation of highly polymeric DNAs on a column with benzoylated DEAE-cellulose is discussed. The method can be used for separation of renaturated and hybrid DNA molecules as well as for detection of single-stranded structures within the DNA. Using the method in question it was shown that the DNA of hepatoma 27 contains about 6% of single-stranded DNA structures.

[Use of benzoylated DEAE-cellulose for the fractionation of high polymeric DNAs]. / Ispol'zovanie benzoilirovannoi DEAE-tselliulozy dlia fraktsionirovaniia vysokopolimernykh DNK.

A method of fractionation of high polymeric DNAs on a column with benzoylated DEAE-cellulose has been developed. For chromatography it has been used a linear gradient of NaCl in a borate buffer, pH 7.0, concurrent with a gradient in ethanol from 0 to 48% (v/v). It has been shown that DNAs from various sources are eluted by two fractions. For complete elution of the second fraction it has been used supplementary solution of 1 M NaCl in a borate buffer, containing 30% dioxane (v/v). DNAs of every fraction distinguish oneself by base composition. The second fraction, containing DNA more high quantity of GC-pair nucleotides. Some advantages of fractionation on benzoylated DEAE-cellulose are discussed.

[A comparative characteristic of DNA pyrimidine sequences of shark, protopterus and perch]. / Sravnitel'naia kharakteristika pirimidinovykh posledovatel'nostei DNK akuly, protopterusa i okunia.

Pyrimidine sequences of DNA from three fishes: shark, protopterus and perch have been studied. These data together with the evidence from the literature were used to support earlier conclusions that dipnoi and cartilagenous fishes should be distinguished as independent classes. The clustering index, beta, and the total molar percentage of long pyrimidine oligonucleotides (Z) containing greater than or equal to 8 nucleotides--a new parameter offered by us--have been used in comparative investigation of DNAs. The new parameter has permitted to obtain a higher resolution in the analysis of our own and literature data on DNA pyrimidine clusters in fishes. Investigation of pyrimidine clusters and of the base composition of individual isoplits of these clusters using statistical analysis showed that DNA from shark, protopterus, sturgeon and perch significantly differ by many features. Significant differences between these DNAs were found also in the base composition. Thus, new evidence for distinguishing cartilagenous fishes and dipnoi as independent classes have been received.

[More precise identification of the systematic position of marine bacteria by the method of DNA-DNA hybridization]. / Ob utochenii sistematicheskogo polozheniia nekotorykh morskikh bakterii metodom gibridizatsii DNK-DNK

In the present work by the method of molecular DNA hybridization there was shown a low degree of affinity of the standard museum strains of cholera vibrios to the respresentatives of the sea species V. parahaemolyticus and V. alginolyticus, and also halophilic vibrios identified earlier on the basis of phenotypical characteristics of the nucleotide DNA composition as Marinovibrio. The presence of only 20--30% of homology in the DNA successiveness in cholera vibrios and the mentioned sea bacteria pointed to the necessity of exclusion of the latter from the Vibrio genus.