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Biomedical subjects

T I Orlova

Publications and source records attributed to T I Orlova.

At least 19 recordsLinked to original sources
PubMed1991

[Fusion of protoplasts of inactive variants of 2 producers of actinomycin C and the biosynthesis of an antibiotic of non- actinomycin nature].

Fusion of protoplasts of double auxotrophic mutants of spontaneous inactive variants of two cultures producing actinomycin C, i.e. Streptomyces chrysomalus 305 and Streptomyces sp. 26-115 induced by PEG-600 yielded a number of stable recombinants. One of the recombinants requiring proline for its growth was designated as recPro. Unlike its parent strains, it synthesized an antibiotic substance active against gram-positive bacteria and Saccharomyces cerevisiae. The nature of the substance is under investigation.

Anti-Bacterial Agents↗
PubMed1990

[The clinico-epidemiological characteristics of the course of a mixed epidemic of influenza and respiratory syncytial infection in Novoshakhtinsk in the summer of 1986].

In the summer of 1986 the epidemic, whose etiological agents were influenza viruses A (H1N1) and respiratory syncytial virus, was registered among the population of Novoshakhtinsk. In a number of mines 15.3-16.7% of the employees were affected. Influenza viruses A (H1N1) proved to be closely related in their antigenic and biological properties to viruses isolated in the USSR in March-June 1986, as well as to viruses A (H1N1), the etiological agents of the epidemic which developed in the USSR in October-December 1986.

Acute Disease↗
PubMed1989

[Use of Streptomyces sp. 26-115 protoplasts inactivated by heating in fusion experiments].

When heated at 55 degrees C for 30 or 60 minutes protoplasts of auxotrophic mutants of Streptomyces sp. 26-115 producer of actinomycin C (active and inactive variants) lost their capacity for regeneration. The protoplasts heated at at 55 degrees C for 30 minutes and not for 60 minutes maintained some ability to yield recombinants on fusion under the effect of PEG 6000. Unlike the parent active strain, the colonies formed by the spores of the prototrophs yielding on fusion of the intact protoplasts showed wide ranges of antibiotic activity against M. flavus while a significant part of the colonies was inactive. The use of the inactive variant protoplasts heated at 55 degrees C for 30 minutes in the fusion procedure increased the proportion of the inactive variants.

Hot Temperature↗
PubMed1988

[Reduction of actinomycin biosynthesis during protoplast regeneration in an inactive variant producer].

During regeneration of protoplasts in the inactive variant H-2 of the actinomycin-producing organism Streptomyces sp. 26-115 there were detected 1-4 per cent of the colonies synthesizing the antibiotic. The frequency of such colonies (H-2R) did not increase after exposure of the H-2 protoplasts to the fusing agent PEG-1000. The population grown from one colony after three passages on pea agar was sufficiently homogeneous by the antibiotic production property. Variant H-2R was more stable to the effect of streptomycin than the initial variant H-2.

Bacteriological Techniques↗
PubMed1986

[Changes in the permeability of streptomycete cytoplasmic membranes due to gramicidin S and its derivatives].

Exposure of intact mycelium and protoplasts of Streptomyces sp. 26-115 to gramicidin S resulted in impairment of permeability of the cytoplasmic membranes thus inducing a loss of low molecular compounds by the cells and protoplasts. Aminoacyl and guanyl derivatives of gramicidin S with respect to the delta-amine group of ornithine were somewhat less effective with respect to the streptomycete membranes. The same as the initial antibiotic, these derivatives had positively charged groups. The changes in the membranes of the streptomycete protoplasts induced by gramicidin S and its derivatives did not result in the protoplast lysis accompanied by decreasing of the suspension optical density. The neutral derivative having no positive charge and not capable of complexing with the membrane phospholipids and the carboxyl-containing derivative with a negative charge showed a low membrane activity when applied to the protoplasts and induced no impairment of permeability of the intact mycelium membranes. The use of phosphates as factors increasing the membrane activity of the gramicidin derivatives having no positive charge is not possible since in the presence of phosphates streptomycete protoplasts are readily destroyed.

Cell Membrane Permeability↗
PubMed1986

[Isolation and regeneration of the protoplasts of the streptomycete producers of actinomycins C and X].

Protoplasts of S. michiganensis, S. chrysomallus and Streptomyces sp. 26-115, organisms producing actinomycins C and X form in hypertonic salt solution under the action of 3-4,5 mg/ml of lysozyme on the mycelium suspension. For protoplasting, the streptomycetes were grown on the soybean medium in the presence of 0.2-0.8 per cent of glycine. The mycelium of the streptomycete exponential growth phase was more favourable for protoplast formation. Protoplast regeneration was studied on the medium described by Okanishi et al. The quantitative composition of this medium was not optimal for regeneration of protoplasts of the above streptomycetes. The level of their regeneration depended to various extents on concentration of phosphate, magnesium and calcium ions and sucrose in the regeneration medium.

Culture Media↗
PubMed1982

[Comparative biochemical study of 2 natural inactive variants of the actinomycin C producer Actinomyces sp. 26-115 with varying sensitivity to actinomycin].

Two natural variants of the actinomycin C-producing organism Actinomyces sp-26-115, i.e. H1 and H2 differ in their sensitivity to exogenic actinomycin, colony morphology, growth dynamics on the synthetic medium and stability to ultrasound and lysozyme. Both variants synthesize no actinomycin. Variant H1 is sensitive to exogenic actinomycin, while variant H2 is resistant to it. Variants H1 and H2 have some similarity in the composition of membrane proteins. Still, they differ in the protein molecular masses, which are equal to 600000--500000, 220000, 130000. The active variant A and nonactive variant H2 have the most similar compositions of membrane proteins. These variants are also close in their growth dynamics, colony morphology, sensitivity to ultrasound and lysozyme. The membranes of all the variants studied contain phosphatidyl ethanol amide as the main phospholipid component. Insignificant differences are observed only with respect to the minor components. The content of teichoic acids in the cell walls of variant H2 is very high, slightly changes during the developmental stage and insignificantly increases on addition of actinomycin to the medium. The cell wall of variant H1 contains less amounts of teichoic acids. During the developmental stage they are liberated from the wall at a higher rate than peptidoglycan. The sensitivity to actinomycin does not increase with an increase in the culture age. It is probable that teichoic acid of the cell wall is one of the factors providing resistance to actinomycin in variant H2. It may be considered as a barrier preventing transport of exogenic actinomycin into the cell.

Actinomyces↗
PubMed1981

[New actinomycin from Actinomyces sp. No. 2].

A new actinomycin was isolated from a mixture of actinomycins formed by Actinomyces sp. No. 2, an organism producing auranthin, an actinomycetous antibiotic. The peptide chains of the new actinomycin contain such amino acids as threonine, valine, proline and sarcosine in a ratio of 2 : 4 : 2 : 2. N-Methyl-valine characteristic of all actinomycins is replaced in position 5 of both pentapeptide chains of the new actinomycin by valine. The new actinomycin is actinomycin D undermethylated in position 5 by valine. When the growing culture of Actinomyces olivobrunneus producing actinomycin D was exposed to sulfadimesine, an inhibitor of biological methylation, production of actinomycin D0 (sarcosine replaced by glycine in one of the pentapeptide chains) markedly increased, which indicated impairment of the glycine residue methylation. Still, no impairment of the valine residue methylation in position 5 of the pentapeptide chains was observed an no actinomycin with N-methyl-valine replaced by valine was formed.

Actinomyces↗
PubMed1981

[Characteristics of the active and inactive variants of Actinomyces sp. 26-115, a producer of actinomycin C].

Two natural variants, i.e. No. 1 and No. 2, not producing actinomycin were isolated from cultures of the actinomycin C-producing organism Actinomyces sp. 26-115. Variant No. 1 differed from the active variant by the growth dynamics and colony morphology. Variant No. 2 was close to the active variant by the growth dynamics. It was shown with electron microscopy that the cells of variant No. 1 differed from those of the active variant in the number and form of the mycelial septa, more even and compact structure of the cell walls and higher sensitivity to actinomycin. Still, they were more stable to the effect of lysozyme and ultrasound. The cell walls of the inactive variant No. 1 gradually lost teichoic acid during development, while the loss of peptidoglycan was observed only on transfer to the stationary phase. The cell walls of the active variant lost teichoic acid and peptidoglycan at the same time on transfer to the stationary phase. Peptidoglycans of both variants contained diaminopimelic acid (the configuration of which was not determined) and glycine (1:1) as differentiating amino acids. The two adjacent tetrapeptides were joined with one glycine radical. The peptidoglycan peptide chains of both variants contained muramic, glutamic and diaminopimelic acids and alanine (1:1:1:2). The peptidoglycans of the inactive variant No. 1 contained in addition valine and isoleucine. However, it is hardly probable that they are contained by the peptidoglycan peptide chains.

Actinomyces↗
PubMed1981

[Membrane proteins of active and inactive variants of Actinomyces sp. 26-115, a producer of actinomycin C].

Some properties of the membrane proteins of Actinomyces sp. 26-115, i. e. its active variant and a variant not producing actinomycin C were studied comparatively. The membrane proteins of both variants of all ages tested represented a heterogenous fraction including about 30 protein components with a molecular mass of 17000 to 500000. There were differences in the protein component composition of the active and inactive variants. The membrane proteins of the active variant contained much more disulfide bonds than those of the inactive variant. It was shown in the model experiments on the protein binding of the phospholipid-lecithin membranes that the membrane proteins of the active variant bound higher amounts of lecithin during the whole developmental cycle than those of the inactive variant. It is suggested that the membrane proteins of the active variant had conformation differences as compared to those of the inactive variant.

Actinomyces↗
PubMed1979

[Aspects of the biosynthesis of actinomycin C].

The protoplasts of Actinomyces sp. 26--115 producing actinomycin C were obtained by the action of lysozyme on the mycelial paste of a 48-hour microbial culture. The protoplast capacity for synthesizing actinomycin was decreased as compared to that of the intact mycelium. The transport of L-isoleucine, a precursor of actinomycin C biosynthesis in the protoplasts also decreased but this could not be the only cause of the decrease in the actinomycin biosynthesis capacity. The biosynthesis of actinomycin C by the protoplasts of Actinomycin sp. 26--115 did not require galactose and was not inhibited by glucose and exogenic actinomycin.

Actinomyces↗
PubMed1979

[Isolation of the membranes of Actinomyces sp. 26-115, a producer of actinomycin C].

A summation fraction of the membranes of Actinomyces sp. 26-115 was obtained as a result of lysis of its protoplasts in a hypotonic medium. The qualitative content of protein, lipids, phospholipids, nucleic acids, glucosamine and muramic acid was determined in the membranes at various stages of the organism development. Phosphatidylcholine is the main component of phospholipids in this organism. Intracellular actinomycin was found inside the protoplasts. Electrophoregrams of the microprotoplasts and membranes are presented. Actinomycin was also detected in the membranes. Still, it is not clear whether it is a component of the membrane or it is adsorbed on the membrane during the process of its isolation. The final conclusion on the relationship between the membrane and localization of actinomycin in the cell requires further investigation.

Actinomyces↗
PubMed1977

[Source of valine for protein V biosynthesis in a producer of actinomycin C].

The specific activity of 14C-valine in valyl-tRNA formed during incubation of the actinomycin C-producing organism with 14C-valine was constant and lower than that of the whole cell pool. The constancy of the valyl-tRNA was indicative of the presence of a separate compartment for the valine pool used for protein biosynthesis. A lower specific activity of valine in valyl-tRNA as compared to that of the whole cell pool may be indicative of a low rate of valine metabolism in such separate compartment with exogenic 14-valine or a higher concentration of free valine in it as compared to the specific activity of this amino acid at average per cell.

Actinomyces↗
PubMed1976

[L-valine transport by the actinomycete Actinomyces species 26-115, the producer of actinomycin C].

Transport of L-valine by Actinomyces species 26-115, an organism producing actinomycin C depended on L-valine concentration in the medium and temperature and required a source of intrinsic energy. Km for L-valine transport was 3.5.10(-6)--6.0.10(-6) M. It somewhat differed from experiment to experiment. The above system transported also other neutral amino acids. L-isoleucine was a competing inhibitor of L-valine transport. The transport of L-valine was stereospecific. The activity of the transport system was regulated by the intracellular content of L-valine. Probably because of this the amino acid transport depended on the culture age, so far as the level of free valine in the mycelium at various stages of development was different.

Actinomyces↗
PubMed1976

[Heterogeneity of L-valine pool in Actinomyces sp. 26-115 producing actinomycin C].

Free intracellular valine in Actinomyces sp. 26-115 producing actinomycin C its functionally heterogenous. There are at least 2 pools of free valine. One of them supplies valine for protein biosynthesis and the second for the antibiotic biosynthesis. The volume of the pools is estimated. Inadequate reaction of the pools to similar effects is indicative of differences in their properties. The pool participating in protein biosynthesis strives for preservation of its volume. The pool participating in the antibiotic biosynthesis is capable of enlarging its volume to various levels depending on the change in the volume of the common intracellular pool.

Actinomyces↗