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The impact of glycine, added to the cultivation medium, on resistance of Staphylococcus aureus strains to actinomycin D and gramicidin S was studied. The antibiotic resistant strains were isolated after cultivation of the susceptible S. aureus strain 209P on media with increasing concentrations of actinomycin or gramicidin. When the strains were grown on the glycine-containing medium. i. e. under the conditions providing replacement of D-alanine by glycine in the C-end dipeptides of peptidoglycanes, the resistance of the staphylococci to actinomycin markedly decreased. However, in the resistant cells, characterized by significant thickening of the cell walls, the peptidoglycane quantity per a biomass unit did not lower, that was evident of preservation of the wall thickness. At the same time, with addition of glycine to the medium there was observed increased ability of the cells to bind actinomycin. When the gramicidin-adapted strains were grown on the glycine-containing medium, their resistance to the antibiotic did not change. The modification of the peptidoglycane C-end dipeptides probably lowered the protective role of the thicker walls of the cells on their contact with actinomycin but not gramicidin.

Chromosome banding patterns of Allium cepa L. were obtained by using fluorochrome combinations chromomycin A3 (CMA) + 4',6-diamidino-2-phenylindole (DAPI), DAPI + actinomycin D (AMD) and propidium iodide (PI) + DAPI. In A. cepa, telomeric heterochromatin displayed dull fluorescence after staining with DAPI and DAPI/AMD. After staining with the GC-specific CMA and AT-specific DAPI, the CMA-positive fluorescence of the NOR region and the telomeric bands of C-heterochromatin was observed. In combination with DAPI, PI, a dye with low AT/GC specificity, produced almost uniform fluorescence of chromosomal arms and heterochromatin, whereas the NOR-adjoining regions displayed bright fluorescence. Denaturation of chromosomal DNA (95 degrees C for 1-3 min) followed by renaturation in the 2 x SSC buffer (37 degrees C, 12 h) altered the chromosome fluorescence patterns: specific PI-positive bands appeared and the contrast of CMA-banding increased. Bright fluorescence of the NOR and adjoining regions was also observed in the case. Three-minute denaturation led also to a bright PI-positive fluorescence of telomeric heterochromatin. The denaturation of chromosomal DNA before staining results in changes of the DAPI fluorescence pattern and in the appearance of DAPI fluorescence in GR-rich NOP regions. The mechanisms underlying the effects of denaturation/renaturation procedures on chromosome banding patterns obtained with different fluorochromes are discussed.

The effects on cloned DNA fragment carrying an actinomycin resistance determinant on physiological processes in streptomyces strains with various potencies in producing this antibiotic, their inactive mutants, and model strain of Streptomyces lividans 66 were studied. This fragment was shown to modulate bacterial resistance to actinomycin and biosynthesis of antibiotics.

The effect of sodium selenite, vitamin E, retabolil and their combinations on the content of ATP, creatine phosphate (CP) and inorganic phosphorus in the liver and skeletal muscle was studied in 3 groups of white rats (one- and two-month old and adults). Sodium selenite (30 micrograms/kg), vitamin E (50 mg/kg), retabolil (4 mg/kg) and their combination administered in a single subcutaneous dose for 14 days increased the content of ATP, CP and inorganic phosphorus in the liver and skeletal muscle after these parameters had decreased because of aurantine administration (50 micrograms/kg). Combined use of sodium selenite, vitamin E and retabolil appeared to be most efficacious.

Mycoplasma arthritidis was shown earlier to induce erythropoietin-independent erythropoiesis in infected mice. This study demonstrated the increased 59Fe incorporation in the mouse spleen as early as day 4 after infection with M. arthritidis. It is known that inoculation of mice with low doses of actinomycin D (Act D) results in a specific suppression of erythropoiesis without impairing the endogenous erythropoietin production. In this study the mice were injected with Act D (80 microgram/kg body weight) daily for 5 days. One hour after the last injection the mice were sublethally irradiated and then infected with either M. arthritidis or A. laidlawii. The effect of Act D was completely reversed by both mycoplasmas which was shown by means of endogenous colony formation (there was almost no endogenous colony formation in the spleen of non-infected mice that were given Act D). The data indicate that the target cells for the mycoplasmas probably reside within the population of primitive erythropoietin-independent precursors.

The binding of the antibiotic dyes to chromatin fragmented by various ways and to preparations of "complete" (MH3, 206 DNA base pairs) and "minor" MH1, 155 DNA base pairs) nucleosomes was studied. The latter were obtained from the total hydrolysate of nuclear chromatin hydrolysis by Ca-Mg-dependent endonuclease, using preparative electrophoresis in polyacrylamide gel. In liver chromatin of different vertebrate species the actinomycin D binding is decreased by 70% as compared to DNA binding, while that of ethidium bromide is reduced only by 40%. The splitting of part of internucleosomal DNA by Ca-Mg-dependent endonuclease further decreases the number of binding sites for ethidium bromide, but not for actinomycin D. MH3 bid 24 molecules of actinomycin D per 10(3) of nucleotides; their DNA contain 43.4% of GC-pairs. The GC content in MH1 is 47.7%; they bind 28 dye molecules per 10(3) of nucleotides. The data obtained are discussed in terms of possible predominant localization of nucleosomal cores in GC-pair-rich DNA sites.

Mesenteric, bifurcational, axillary and popliteal lymph nodes have been studied in 22 healthy mature male dogs. Amount of blast cells, small lymphocytes, plasma cells and macrophages has been taken into account in the paracortical zone, in the germinative centers and in the medullary cords. For two weeks to one group of the animals every day imuran in turn with aurantin (10 mg/kg and 25 mg/kg) are injected, or antilymphocytic serum (ALS) intraperitoneally every other day (0.1 ml/kg). The combined injection of imuran and aurantin produces a more pronounced toxic effect to the hemopoietic organs than ALS. ALS is more specific for T-dependent zones of the lymph nodes. In the dose and interval mentioned ALS is an immunostimulating preparation for the immunocompetent cells of the germinative centers of the lymph nodes. The reaction of the lymph nodes depends on their regional belonging.

The levels of total DNA, RNA and protein synthesis were examined in control and in vivo irradiated thymocytes after their preincubation with exogenous DNA of different polymerization degree. The studies were made using the uridine-14C and lysine-14C. The influence of preliminary treatment of exogenous DNA or cells with actinomycin D (AMD) was studied as applied to the levels of their own and "induced" synthesis in the cells. It is shown that native exogenous DNA induced the increase in the synthesis of all three components only in the irradiated cells. The pretreatment of the irradiated cells or exogenous DNA with AMD completely inhibits the "induced" synthesis of RNA and protein while their own synthesis in suppressed only by 20%. Possible transcription and translation of highly polymerized exogenous DNA in the irradiated cells without its integration into the genome of the "host" is discussed.

It is shown that distamycin A and actinomycin D protect the recognition sites of certain restriction endonucleases from the attack by these nucleases due to specific interaction of these antibiotics with double-stranded DNA. Distamycin A protects A-T containing sites and actinomycin G-C rich sites. Among Hind II recognition sites which have alternative structure (GTPyPuAC) distamycin A protects only Hpa I similar sites (GTTAAC). It is shown with several restriction endonucleases that antibiotic action depends on the nucleotide sequences in the recognition sites and in their closest environment. Proper concentrations of antibiotic give rise to larger fragments. Use of both distamycin A and actinomycin D allows to obtain a set of overlapping fragments. The data obtained with various DNAs and restriction endonucleases allow to conclude that these antibiotics may be useful for DNA mapping and for preparation of large functional fragments of DNA.

It is shown that antibiotics actinomycin D (AM), netropsin (Nt), distamycin A (DM) and the propyl analogue of distamycin A (pDM) being complexed with DNA are located within the narrow groove of DNA. A comparative investigation of the 3H-dimethyl sulphate methylation extent of free calf thymus DNA and its complexes with AM, Nt, DM and pDM reveals that upon DNA saturation these antibiotics decrease the methylation level of the narrow groove (AM by 30%, pDM by 50%, DM by 65% and Nt by 70%). In the triple complex of DNA+AM+DM the methylation level of the narrow groove drops by 80%. The large groove is not shielded by these antibiotics at all. However, the methylation level of the large groove decreases by 50% for T6 phage DNA due to the presence of glucosyl residues linked to 5-hydroxymethylcytosine within the large groove. The binding of AM to DNA saturated with Nt or with the analogue of distamycin A (DM2) containing the 2 N-methylpyrrole residues has been investigated by spectrophotometry. The apparent number of binding sites for AM in these 2 complexes is about half as much as observed for free DNA while the saturation level of the binding decreased only by about 20%. This proves simultaneous presence of AM and Nt (DM2) within the narrow groove of DNA.

The DNA components of B. nigra were preparatively separated by equilibrium ultracentrifugation in a CsCl density gradient, the buoyant density of the main component being 1,696 g . cm-3, that of the satellite component--1,704 g . cm-3. The properties of individual DNA fractions were investigated. Four major components could be observed on the differential melting curve of satellite DNA. Using the reassociation kinetics method it was shown that 30% of satellite DNA are presented as a fast reassociating component with a length of a repeated unit of approximately 2,5 . 10(3) nucleotide pairs. The calculated values of Tm and buoyant density suggest that the m5C content in satellite DNA is lower than that in the main component. During equilibrium ultracentrifugation in the density gradients of actinomycin D--CsCl and Hg2+--Cs2SO4 the satellite DNA is split into 4 major components.

Experimental studies are reported on the binding of actinomycin D to various synthetic and naturally occurring DNAs. The experimental data obtained agree with a model in which the antibiotic molecule carries only one GC-specific reaction center and covers 5 base pairs upon binding to DNA. Positive cooperative effects are observed for the binding of actinomycin to poly(dG-dC)-poly (dG-dC) duplex.

The activity and properties of RNA-dependent RNA-polymerase in cells infected with Venezuelan equine encephalomyelitis virus were studied. The maximum activity of the enzyme was found 4-5 hours after infection. The effect of two synthetic drugs (rimantadine and diacetylaminocyclohexenon) with antiviral activity against some viruses on RNA-polymerase was studied. Rimantadine was shown to have no effect on the synthesis and activity of the enzyme. Diacetylaminocyclohexenon added into the growth medium was found to inhibit production of RNA-polymerase by 35-40% without reducing the activity of the enzyme in vitro.