[Transmission and exchange of genetic information during bacterial conjugation in ground-based simulations of the factors of orbital flight]. / Peredacha i obmen geneticheskogo materiala pri bakterial'noi kon"iugatsii v nazemnykh éksperimentakh, imitiruiushikh usloviia orbital'nogo poleta.

Control laboratory experiments on bacterial conjugation under simulated spaceflight conditions were performed with the use of new equipment (bioreactor RECOMB-2 and container BIOMAGNISTAT) within the RSA-NASA science program. External parameters were selected and the plan of simulation of a space experiment was verified to ensure high efficiency of the conjugative transfer of chromosomal and plasmid DNA and storage of hybrids on the ground. Genetic analysis of conjugative hybrids E. coli supported the hypothesized possibility of transfer of a whole bacterial chromosome during conjugation that will lead to relative stabilization of the diploid state. Earlier this hypothesis was used to interpret results of experiments performed on MIR in 1992-1993. Hence, the ground laboratory investigations proved the conclusion about high probability of transfer of large fragments or even a whole chromosome during space flight. Screening of the geomagnetic field by BIOMAGNISTAT increases the probability of conjugative contacts between cells and is likely to slightly inhibit the processes of recombination.

[Preparation and regeneration of protoplasts from Bacillus megaterium cells dried by sublimation]. / Poluchenie i regeneratsiia protoplastov iz sublimatsionno vysushennykh kletok Bacillus megaterium.

Bacterial protoplasts are widely used in genetical research, for instance, in protoplasts fusion experiments and the transfer of heterologous DNA into bacterial cells. The usage of a new fresh grown culture of bacteria in every experiment restricts the reproducibility of the results preventing the technique becoming widespread. The use of antioxidants as components of stabilizing medium for sublimation drying of Bacillus megaterium cells supported cellular viability in bacterial culture. It also made possible preservation of such cellular fundamental properties as the ability to form protoplasts and regenerate the cell wall. Efficiencies of protoplasts formation and generation are similar for lyophilized and fresh grown cells. Cellular properties are conserved for 6 months of storage at least. Experiments with a lot of lyophilized biomass samples are highly reproducible. The potential of the technique was demonstrated in obtaining the hybrid Bacillus megaterium colonies by fusion of protoplasts derived from lyophilized genetically marked strains stored for up to 6 months.

[Liposomes as a carrier of genetic information]. / Liposomy kak perenoschik geneticheskoi informatsii.

Incorporation of genetic material into the bilayer lipid vesicles (liposomes) and the subsequent transfer of liposomal content into cells or protoplasts appear to be a promising technique for transfer of genetic information. The following three methods are most frequently used to incorporate DNA into liposomes lipid microinjection into aqueous phase, multistep treatment of the lipid suspension by ultrasonication, Ca2+ ions and EDTA, reverse phase evaporation. Viral particles, chromosomes, nuclei, viral nucleic acids, plasmids and chromosomal DNA can be successfully transferred into animal and plant protoplasts by the described technique. Successful transformation of a number of microorganisms (Neurospora, E. coli, B. subtilis, Streptomyces, Mycoplasma) with the liposome incorporated DNA has also been reported. Transformation frequency can be considerably increased by optimizing the conditions of liposome formation or of liposome-protoplasts interaction.

[Incorporation of plasmid DNA into liposomes from the total lipid of E. coli and determination of their stability]. / Vnedrenie plazmidnoi DNK v liposomy iz total'nogo lipida E. coli i opredelenie ikh stabil'nosti.

Large monolamellar liposomes were constructed from the total E. coli lipid by ultrasonication and consecutive treatment with Ca2+ and EDTA. Serum albumin and plasmid DNA were incorporated into the liposomes with the efficiency of 6.3 and 4.7%, respectively. The plasmid DNA remained intact after incorporation, as was demonstrated by gel electrophoresis and transformation of E. coli with the DNA extracted from the liposomes, About one half of DNA-containing liposomes remained undamaged after 10 hr incubation at 4 degrees C. Possible implications of E. coli lipid liposomes in genetic transformation are discussed.

[Changes in RNA biosynthesis in the liver of chicks with coccidiosis]. / Izmeneniia biosinteza RNK v pecheni tsypliat pri koktsidioze.

The RNA fraction and the intensity of their turnover in chick liver during experimental coccidiosis was studied. A marked (about 60%) increase of intensity of mRNA turnover with no changes in its amount was found. It was shown that pre-rRNA biosynthesis was significantly enhanced and, due to it, the amount of both pre-rRNA and mature 18S rRNA was increased while the level of 28S rRNA was unchanged. The relations between the observed changes of RNA biosynthesis and protein biosynthesis in liver in coccidiosis as well as the role of these changes in pathological process studied are discussed.

[RNA biosynthesis and regulation of protein biosynthesis in the liver of chicks with experimental coccidiosis]. / Biosintez RNK i reguliatsiia biosinteza belkov v pecheni tsypliat pri éksperimental'nom koktsidioze.

The aim of this work was to investigate the interrelationship between RNA biosynthesis and that of protein in chick liver during experimental coccidiosis induced by E. tenella. The peculiarity of this model is that in the course of this disease protein synthesis is significantly intensified inspite of the fact that the rate of the biosynthesis is rather high under normal conditions. It has been shown that 4 to 6 days after infection incorporation of labeled amino acids into proteins from chick liver subcellular fractions is greatly increased. The most pronounced changes are in ribosomal and mitochondrial fractions as well as in the postribosomal supernatant. At the same time the specific radioactivity of serum albumin excreted by liver was increased by factor 3. These changes in protein biosynthesis are associated with a significant increase of both the content and intensity of biosynthesis of high molecular weight precursors of rRNA as well as with those of mature 18S rRNA. The amount of 28S rRNA and mRNA per cell is practically without any changes whereas the mRNA turnover is somewhat more extensive. The selective accumulation of 18S rRNA is suggested to be responsible for the intensification of protein biosynthesis.

[Isolation of RNA containing a polyadenylic acid sequence by chromatography on unmodified cellulose]. / Vydelenie RNK, soderzhashchikh posledovatel'nosti poliadenilovoi kisloty, khromatografiei na nemodifitsirovannoi tselliuloze

A new modification of the procedure of the isolation of polyA-containing RNAs is worked out, which makes possible to isolate this RNA fraction free of considerable contamination with rRNA. The administration of 0.0001 M EDTA-Na2 provides the absence of RNA aggregation and prevents non-specific RNA binding on cellulose columns, which takes place when more high EDTA-Na2 concentrations in elution solutions are applied. Under these conditions synthetic polyA in model experiments practically completely binds with cellulose in a broad range of concentrations. It permits to use the procedure described for the preparative isolation of RNA fractions, containing polyA sequences.

[Influence of fast electrons on the nucleic acid level and the biosynthsis of RNA in cells of the ascites tumor NK/Ly and the spleen of tumor-bearing mice]. / Vliianie bystrykh élektronov na soderzhanie nukleinovykh kislot i biosintez RNK v kletkakh astsitnoi opukholi NK/Ly i selezenke myshei-opukholemositelei

The results of investigations on total nucleic acids content and RNA turnover in the cells of tumor NK/Ly and of the spleen in tumor-bearing mice after single exposure to fast electrons are described. In every case the irradiation results in reliable changes of parameters under study. The pattern of changes in nucleic acids content and turnover in the spleen after the exposure to fast electrons is in a good agreement with the available data concerning the influence of x- and y-radiation. The irradiation action on nucleic acids content and turnover in ascites tumor NK/Ly cells is qualitatively and quantitatively similar to that in splenic cells.