[Yeast resistance to polyene antibiotics. IV. A study of the inheritance of changes in the sterol composition of Saccharomyces cerevisiae yeasts caused by mutations of nystatin resistance]. / Rezistentnost' drozhzhei k polienovym antibiotikam. Soobshchenie IV. Izuchenie nasledovaniia izmenenii v sostave sterinov, obuslovlennykh mutatsii ustoichivosti k nistatinu u drozhzhei Saccharomyces cerevisiae.

Sterol content in haploid and diploid strains of yeast having mutations of resistance to nystatin were studied by UV spectrometry method. Heterozygous diploids carrying one or two nystatin resistance mutations have, as a rule, the sterol content of the wild type strains. Segregants of the same genotype demonstrate differences in sterol content. Double mutants nys1 nys2 and nys1 nys3 have UV spectra typical for single nys2 and nys3 mutants, respectively. Double mutants nys1 nysX are characterized by a "mixed" UV spectra of sterols.

[Yeast resistance to polyene antibiotics. II. An analysis of the sterol composition of Saccharomyces cerevisiae yeasts resistant to nystatin]. / Rezistentnost' drozhzhei k polienovym antibiotikam. Soobshchenie II. Analiz sostava sterinov u drozhzhei Saccharomyces cerevisiae, ustoichivykh k nistatinu.

The recessive yeast mutations nys providing resistance to polyene antibiotics in Saccharomyces cerevisiae are described. The analysis of UV-absorbtion spectra of sterols from cells of different mutants allows to assume that NYS genes control synthesis of ergosterol. The lack of alterations in the sterol composition of the same strains carrying dominant nystatin resistance mutations points to the existence of another mechanisms of resistance to polyene antibiotics, in addition to the sterol mechanism.

[Yeast resistance to polyene antibiotics. III. Phenotypic analysis of polyene-resistant sterol mutants of Saccharomyces cerevisiae yeasts]. / Rezistentnost' drozhzhei k polienovym antibiotikam. Soobshchenie III. Femotipicheskii analiz polienrezistentnykh sterinovykh mutantov drozhzhei Saccharomyces cerevisiae.

The pleiotropic effects of nystatin resistant mutations have been studied. It has been shown that resistance to nystatin is often accompanied by temperature-sensitivity and, in some cases, by osmotic remedial sensitivity. The dependence of the expression of the mutations on temperature is demonstrated. A new type of conditional nystatin-dependent mutants is found. All nys2 mutants have a defected membrane and are stained on a methylene blue containing media. At the same time, the mutations under investigation do not affect the respiratory competence and the exoenzyme activity of acid phosphatases.

[Yeast resistance to polyene antibiotics. I. Production of Saccharomyces cerevisiae mutants resistant to nystatin and their genetic analysis]. / Rezistentnost' drozhzhei k polienovym antibiotikam. Soobshchenie I. Poluchenie mutantov Saccharomyces cerevisiae, rezistentnykh k nistatinu, i ikh geneticheskii analiz.

239 nistatin-resistant mutants were selected after UV-irradiation of yeasts. Phenotypical analysis has revealed two main groups of the mutants: 1) resistant to nistatin and resistant or sensitive (in different combinations) to haptaens; 2) resistant to nistatin and having an increased resistance to haptens. It is found that the sensitivity dominates over the resistance and hyper-resistance. Genetic analysis of the mutant collection has shown that the resistance to nistatin is determined by 5 nuclear genes (hysr). Hyper-resistance is controlled by mutations in other genes, which are not connected with stable phenotype. Genes of hyper-resistance can be considered as minus-modificators of pleiothrophic cross-resistance, characteristic of hysr genes. Plus-modificator genes of polyenic resistance are described. The gene hysr1 is linked with its chromosome.

[Supersensitivity to levorin and amphotericin B in several Saccharomyces cerevisiae mutants resistant to nystatin]. / Superchuvstvitel'nost' k levorinu i amfoteritsinu v nekotorykh mutantov Saccharomyces cerevisiae, rezistentnykh k nistatinu.

104 mutants resistant to nystatin were isolated after UV-treatment of two haploid marked strains of Saccharomyces cerevisiae. The analysis of resistance to three polyene antibiotics allowed to determine 8 phenotype classes of mutants including those resistant to nystatin but in various combinations showing hypersensitivity to levorin and (or) amphotericin B. The analysis of UV absorption spectra of sterolic extracts prepared from cells of different mutants showed that similar quality changes in sterol composition could be associated both with polyresistant an supersensitive phenotype. New type of mutants resistant to nystatin and supersensitive to levorin and (or) amphotericin B seems to be promising for studies on the mechanisms of action of polyene antibiotics, the bases of resistance to them and also in consideration of the possibility to increase the efficiency of antimycotic antibiotic therapy.

[Effect of biologically active compounds on the resistance of bacteria to antibiotics]. / Vliianie biologicheski aktivnykh soedinenii na ustoichivost' bakterii k antibiotikam

A number of biologically active substances, i. e. main protamine proteins and histones, EDTA, lysozyme, methacyl and pentoxyl was studied with respect to their effect on the levels of the minimum inhibitory concentrations of antibiotics against E. coli and Staph. aureus and transfer of resistence to chloramphenicol in E. coli on conjugation. It was shown that the above substances lowered the minimum inhibitory concentrations of the antibiotics 2--10 times when added to the culture simultaneously with the latter. The results varied depending on the strain and the resistance nature. Marked inhibition of transfer of resistance to chloramphenicol in the presence of the main proteins and EDTA was found.