Acid excreting mutants of yeast Saccharomyces cerevisiae.

Saccharomyces cerevisiae mutants acidifying glucose medium containing bromocresol purple were shown to excrete protons when placed in unbuffered water in the absence of any external carbon source. The mutants belong to 16 different complementation groups. Most of them do not grow on glycerol and the excreted protons are associated to particular sets of organic anions such as citrate, aconitate, succinate, fumarate or malate. These novel types of respiratory mutations seem to be located in genes operating in the Krebs or glyoxylate cycle.

Comparative studies of the biological activities of lysosomotropic aminoesters and quaternary ammonium salts on the yeast Saccharomyces cerevisiae.

The biological activity of lysosomotropic n-alkyl N,N-dimethylglycinates (DMG-n) was compared with that of a quaternary ammonium salt IM (methochloride of DMG-12). The activity of the glycinates appeared to be carbon chain length dependent and was similar at pH 6 and pH 8. Nutritional auxotrophy and respiratory deficiencies have no influence on DMG-n sensitivity. Both IM and DMG-n inhibit plasma membrane H+-ATPase activity while mitochondrial ATPase is relatively non-sensitive to glycinates. No cross-resistance to IM and DMG-n was observed.

Studies of antibacterial activity of binuclear rhodium (II) complexes with heterocyclic nitrogen ligands.

Binuclear rhodium (II) complexes, [Rh2(OOCPh)2(phen)2(H2O)2] (OOCPh)2 (1), [Rh2(OOCPh)2(bpy)2(H2O)2] (OOCPh)2 (2), [Rh2(OOCBu(n))2 (bpy)2(H2O)2] (OOCBu(n)2 (3), and [Rh2(OOCPr(n)2 (phen)2(H2O)2] (OOCPr(n)2 (4) (Phen = 1,10-phenanthroline and bpy = 2,2'-bipyridine), have been synthesized and characterized using NMR, IR and electronic spectra. Activity of these compounds against Gram-positive bacteria decreases in the order: 1?2?3 > 4. Complex 1 is active against many Staphylococcus strains resistant to commonly used antibiotics. The complexes 1-4 are much less active agents against Gram-negative bacteria.

Genetical and biochemical characterization of cycle Krebs mutant in yeast.

We present the results of genetical and biochemical investigations of yeast mutants which presumably are deficient in different steps of the Krebs cycle. The investigation of the activities of the Krebs cycle enzymes suggests that we have isolated two types of mutants: structural and regulatory.

Binuclear Rhodium(II) Complexes With Selective Antibacterial Activity.

Binuclear rhodium(II) complexes [Rh(2)Cl(2)(mu-OOCR)(2)(N-N)(2)] {R = H, Me; N-N = 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen)} and [Rh(2)(mu-OOCR)(2)(N-N)(2)(H(2)O)(2)](RCOO)(2) (R = Me, Et;) have been synthesized and their structure and properties have been studied by electronic, IR and (1)H NMR spectroscopy. Antibacterial activity of these complexes against Escherichia coli and Staphylococcus aureus has been investigated. The most active antibacterial agents against E. coli were [Rh(2)Cl(2)(mu-OOCR)(2)(N-N)(2)] and [Rh(2)(mu-OOCR)(2)(N-N)(2)(H(2)O)(2)](RCOO)(2) {R = H and Me} which were considerably more active than the appropriate nitrogen ligands. The complexes show low activity against S. aureus. The activity of the complexes [Rh(2)(OOCR)(2)(N-N)(2)(H(2)O)(2)](OOCR)(2) against E. coli decreases in the series: R=H congruent withCH(3)>C(2)H(5)>C(3)H(7) congruent withC(4)H(9). The reverse order was found in the case of S. aureus.

[Bacterial antigenic structure of Shigella flexneri serotype 1B and its 3B serotype mutant and susceptibility to bacterial action of complement in normal bovine serum]. / Budowa antygenowa bakterii Shigella flexneri serotypu 1B i mutanta serotypu 3B a wrazliwosc na bakteriobójcze dzialanie dopelniacza normalnej surowicy bydlecej.

The susceptibility of S. flexneri 1b and 3b strains to killing action of serum was investigated. Differences in sensitivity to bactericidal action of complement appeared to result from different structure of their LPS-es. The protective effect of LPS-es depends both on their origin and concentration.

Population dynamics in the co-culture of Shigella flexneri 1b original strain and its antigenic 3b mutant carrying a prophage.

The antigenic mutant Shigella flexneri 3b showed selective prevalence when subcultured with the original strain 1b. Mathematical analysis of such co-cultures showed that the dynamics of bacterial growth may be described by equations of the Lotka-Volterra type. The analysis of serial cultivations suggests that parameters of the equations may be realizations of random variables characterizing strains and media. The mutant carries a prophage lethal for the original strain. Distinctive features of the growth of these strains alone and in co-culture may be successfully explained by the differences in growth parameters, without phage inference. The concurrence model connected only with the existence of the phage is not sufficient. A complete description of the dynamics of the co-culture is obtained by the connection of the assumptions of two models: strains in competition and growth of strains with phage, given the random character of the parameters.

Mechanism of antigenic variation in Shigella flexneri bacilli. III. Complement sensitivity of S. flexneri 1b strains and their 3b variants selected either as Lac+ recombinants or phage F2 resistant mutants.

Several S. flexneri 1b serotype strains of clinical isolation were compared with their 3b serotype variants isolated either as Lac+ recombinants from crosses of S. flexneri x E. coli Hfr C, or F2-resistant mutants. The studied variants 3b were deprived of type I antigen but acquired type III antigen. They appeared to be less sensitive to killing action of complement present in normal bovine serum although kinetics of killing and its effectiveness differed between the strains.

A probabilistic approach to the analysis of the frequency of diploid formation in yeast (Saccharomyces cerevisiae) mating.

Conditions of optimizing mating efficiency in the yeast. Saccharomyces cerevisiae were tested and measured as a number of prototrophic diploids. It was found that the process of diploid formation could be controlled by suitably adjusting cell densities in liquid mating medium and alpha: a mating type cell ratio. When the first was about 5 x 10(8) per ml and the second 1:10, respectively, every alpha cell was able to find a partner of opposite mating type. Some mathematical models of the "courtship" in yeast were advanced and the conclusions are discussed in the light of recent data on mating pathway in S. cerevisiae.

Mechanism of antigenic variation in Shigella flexneri. II. Sensitivity to complement as a selection factor for antigenic mutant 3b in 1b serotype.

In the first report we stated that the antigenic mutant of Shigella flexneri 6713 3b serovar with antigenic formula III: 3, 4, 6 was less sensitive to bactericidal action of normal calf serum in comparison to its parent strain S. flexneri 6713 1b with antigenic formula III: 3, 4, 6. In this paper we show that the phenomenon is rather a general one; the difference in sensitivity was observed in three other strains S. flexneri 1b of independent clinical origin and its antigenic mutants 3b respectively. As the result of serial treatment of these strain with the serum among the survivors the antigenic mutants have been found. In the artificial mixtures of the mutants and isogenic original strains treated with the serum the later show clear cut higher survival.

[Susceptibility of Proteus, Morganella and Providencia strains isolated from patients with urinary tract infections on bactericidal activity of normal human serum]. / Podatnosc szczepów Proteus, Morganella i Providencia izolowanych od chorych z zakazeniami ukladu moczowego na bakteriobójcze dzialanie normalnej surowicy ludzkiej.

Usefulness of the test determining bactericidal activity of normal human serum was investigated with 50 strains of Proteus, Morganella and Providencia isolated from patients with urinary tract infections (UTI) and with 50 strains isolated from feces. It was found that strains from UTI were more frequently resistant to the action of normal human serum (50% resistant) in comparison with strains isolated from feces (30% resistant). Strains of Proteus belonging to four species were differing greatly in their susceptibility to normal human serum. They can be ranked as followings: P. mirabilis (49% of resistant strains), P. vulgaris (62%), P. morganii (72%) and P. rettgeri (100%). In studies on interaction subinhibitory concentrations of cefotaxime and normal human serum in bactericidal reaction, a synergism was found only with some strains.