Motor and Cognitive Functions in Aging C57BL/6 Mice: Association with Activity of the Monoaminergic Systems in the Cerebellum and Frontal Cortex.

The activity in the open field, short- and long-term memory in the novel object recognition test, and gait features were evaluated in 6- and 12-month-old male C57BL/6 mice. The levels of norepinephrine, dopamine, serotonin, and their metabolites were determined in the cerebellum and frontal cortex. In the observed age range, a decrease in locomotion speed, impairment of gait initiation and stability, and long-term memory deficit were revealed. In the cerebral cortex, reduced levels of dopamine and its metabolites and accelerated metabolism of all neurotransmitters under study were found. In the cerebellum, the content of all studied monoamines was elevated, while dopamine metabolism was decelerated. Analysis of correlations between the neurochemical and behavioral parameters showed that the mechanisms of compensation of brain functions during the early aging may be associated with an increase in activity of the monoaminergic systems in the cerebellum.

[Hybrid formation and copulation activity in the yeast Pachysolen tannophilus].

The copulation activity and hybrid formation efficiency have been studied in the xylose-assimilating yeast Pachysolen tannophilus. It was shown that the presence of 2% D-glucose, 0.5% yeast extract, and 2% agarose in the growth medium provided for the highest frequencies of hybrid formation. Atypical hybrid cultures similar in morphophysiological characteristics to native haploid strains of P. tannophilus were revealed in the course of hybridization. The genesis mechanism of such cultures and the reasons for the restricted applicability of hybridological analysis to genetic studies of P. tannophilus are discussed.

[Conditions favoring differentiation and stabilization of the life cycle of the yeast Pachysolen tannophilus].

Conditions favoring differentiation and stabilization of the life cycle of the yeast Pachysolen tannophilus have been studied. When concentrations of the carbon source in the medium were lower than 100 g/l, it was found to be favorable to the mating of vegetative cells, both haploid and diploid. The addition of nitrogen and sulfur sources to the medium influenced the life phases of haploid cells and partially stabilized the vegetative growth of diploid cells. Enrichment of the nutrient medium with potassium, vitamins, and microelements was shown to be necessary for the formation and maturation of conjugated ascospores. Microelements, vitamins, and phosphorus in excessive amounts activated conjugation but did not provide for the distinct phases of formation of unconjugated asci and spores in the diploid cells. Possible reasons for the unstable diplophase in the yeast P. tannophilus are discussed.

[Activity of the key enzymes in xylose-assimilating yeasts at different rates of oxygen transfer to the fermentation medium]. / Aktivnost' kliuchevykh fermentov ksilozoassimiliruiushchikh drozhzhei pri razlichnoi skorosti postupleniia kisloroda v fermentatsionnuiu sredu.

The activities of xylitol dehydrogenase and xylose reductase in the yeasts Candida shehatae, C. didensiae, C. intermediae, C. tropicalis, Kluyveromyces marxianus, Pichia stipitis, P. guillermondii, Pachysolen tannophilus, and Torulopsis molishiama were studied at different oxygen transfer rates (OTRs) to the fermentation medium (0, 5, and 140 mmol O2/(1 h)). The activities of these enzymes were maximum in the yeasts P. stipitis and C. shehatae. The xylitol dehydrogenase of all the yeasts was NAD-dependent, irrespective of the intensity of aeration. The xylose reductase of the yeasts C. didensiae, C. intermediae, C. tropicalis, Kl. marxianus, P. guillermondii, and T. molishiama was NADPH-dependent, whereas the xylose reductase of P. stipitis, C. shehatae, and Pa. tannophilus was specific for both NADPH and NADH. The effect of OTR on the activities of the different forms of xylitol dehydrogenase and xylose reductase in the xylose-assimilating yeasts is discussed.

[The activity of xylose reductase and xylitol dehydrogenase in yeasts]. / Issledovanie aktivnosti ksilozoreduktazy i ksilitdegidrogenazy u drozhzhei.

The activity and the cofactor specificity of xylose reductase and xylitol dehydrogenase were studied in extracts of yeasts from the genera Candida, Kluyveromyces, Pachysolen, Pichia, and Torulopsis grown under microaerobic conditions. It was found that xylitol dehydrogenase in all of the yeast species studied is specific for NAD+; xylose reductase in the xylitol-producing species C. didensiae, C. intermediae, C. parapsilosis, C. silvanorum, C. tropicalis, Kl. fragilis, Kl. marxianus, P. guillermondii, and T. molishiama is specific for NADPH; and xylose reductase in the ethanol-producing species P. stipitis, C. shehatae, and Pa. tannophilus is specific for both NADPH and NADH.

[Specific features of fermentation of D-xylose and D-glucose by xylose-assimilating yeasts]. / Osobennosti fermentatsii D-ksilozy i D-glukozy ksilozoassimiliruiushchimi drozhzhami.

The ability to assimilate D-glucose and D-xylose was studied in 21 yeast species of the following genera: Candida, Kluyveromyces, Pachysolen, Pichia, and Torulopsis. All the cultures fermented D-glucose with the formation of ethanol. During the assimilation of D-xylose, ethanol was produced by P. stipitis and C. shehatae, whereas xylitol was produced by C. didensiae, C. intermediae, C. parapsilosis, C. silvanorum, C. tropicalis, K. fragilis, K. marxianus, P. guillermondii, and T. molishiama. The yeast P. tannophilus produced comparable amounts of both alcohols. The possible use of xylose-assimilating yeasts for the production of xylitol and ethanol is discussed.

[Microbiological synthesis of sterols]. / Mikrobiologicheskii sintez sterinov.

The data on preparation and application of microbial sterols are reviewed. The ways of optimization of ergosterol production are discussed. The microbiological techniques for obtaining other sterols are proposed based on using specific inhibitors and mutants. The data concerning chemical and biological transformation of yeast sterols to androstane hormones and D vitamins are presented.

[Biochemical basis of varying nystatin resistance of Saccharomyces cerevisiae and Candida maltosa mutants]. / Biokhimicheskie osnovy razlichnoi ustoichivosti k nistatinu u mutantov drozhzhei Saccharomyces cerevisiae i Candida maltosa.

Six groups of nystatin resistant mutants of C. maltosa and of haploid and diploid Saccharomyces cerevisiae strains were obtained with the help of genetic and biochemical analysis. It has been shown that every group of the mutants was characterized by a specific level of resistance to nystatin. The dependence of the resistance level upon sterol content has been established. It has been shown that the more the structure of the sterol present differed from ergosterol the higher was the resistance level. The results obtained in vivo permit to make conclusions about the role of different functional groups of sterol molecule in the interaction with nystatin.

Sterol composition of nystatin-resistant Candida maltosa mutants.

Composition of sterol fractions of nystatin-resistant Candida maltosa strains was determined. Using UV-spectrometry, TLC and GLC-MS it was demonstrated that resistance to nystatin is connected with the composition alterations of yeast cell sterols. Block of different stages of ergosterol biosynthesis was revealed in some mutants, viz. C-24-transmethylation, delta 8----delta 7-isomerization, 14 alpha-demethylation, C-5(6)-dehydrogenation, reduction of C-14(15) and C-24(28) double bonds.

[Sterol level in Saccharomyces cerevisiae mutants with altered ergosterol biosynthesis]. / Soderzhanie sterinov v mutantakh drozhzhei Saccharomyces cerevisiae s izmenennym biosintezom érgosterina.

The sterol content in Saccharomyces cerevisiae mutants defective in the synthesis of cyclic ergosterol precursors has been studied. It was found that strains with mutational blocks involving the stages of zymosterol side chain methylation at C24 and delta 8----delta 7 isomerization accumulated twice more sterols as compared to parent strains. Regulation of the ergosterol biosynthesis is discussed.

[The use of various mutagens for induction of nystatin-resistant mutants in Candida maltosa]. / Primenenie razlichnykh mutagenov dlia induktsii nistatinoustoichivykh mutantov u Candida maltosa.

The mutagenic activity of nitrous acid, 6-N-hydroxylaminopurine, N-methyl-N'-nitro-N-nitrosoguanidine and 4-N-nitroquinoline oxide was studied for Candida maltosa. The efficacy of their action on C. maltosa cells was determinded in order to obtain nystatin-resistant strains.

[The level of cytochrome P-450 in Saccharomyces cerevisiae with disruptions of various stages of sterol synthesis]. / Soderzhanie tsitokhroma P-450 v drozhzhakh Saccharomyces cerevisiae s narusheniiami razlichnykh stadii sterinovogo sinteza.

A spectral analysis of cytochromes P-450 in Saccharomyces cerevisiae cells and in mutant strains accumulating the ergosterol biosynthesis intermediates was carried out. Glucose repression and semianaerobiosis were found to induce cytochrome P-450 synthesis. No differences in the cytochrome P-450 content in mutant nys 3, nys 4 and parent strains were observed. Mutants nys 5 accumulated large amounts of cytochrome P-450. Cytochrome P-420 was detected in wild type strains and in mutants nys 3 and nys 4. The cultivation time and aeration conditions were shown to be unimportant for the generation of cytochrome P-420.

[Substrate specificity of the biotransformation enzymes in a Nocardia erythropolis culture]. / Izuchenie substratnoi spetsifichnosti fermentov biotransformatsii kul'tury Nocardia erthropolis.

Substrate specificity of biotransformation enzymes of culture Nocardia erythropolis was studied. Products of transformation of cholesterol and three sterols of microbial origin: ergosterol, ergosta-5,7-dien-3 beta-ol and ergosta-7,22-dien-3 beta-ol was identified with a help of thin-layer chromatography, UV spectrophotometry and mass-spectrometry. It was established, that delta 22-bond in the side chains of sterols and delta 7-bond slows and delta 5-bond makes impossible cleavage of side chains of sterols.

[The effect of oxygen deficiency on the stability of the yeast Saccharomyces cerevisiae to the polyenic antibiotic nystatin]. / Vliianie defitsita kisloroda na ustoichivost' drozhzhei Saccharomyces cerevisiae k polienovomu antibiotiku nistatinu.

Oxygen deficiency was shown to affect the resistance of different Saccharomyces cerevisiae strains to nystatin, a polyenic antibiotic. This resistance decreased upon oxygen deficiency in the wild-type strains alpha'1 and 7A-P192 as well as in the mutant strains NYS 2, NYS 3 and NYS 4, but remained unchanged in the mutants NYS-1 and NYS 5. The qualitative composition of sterols was studied in the strains with a modified ergosterol synthesis, which were grown under the conditions of oxygen deficiency. Such conditions exerted a considerable effect on the accumulation of intermediate products in ergosterol biosynthesis.

[Characteristics of the final stages of ergosterol biosynthesis in Saccharomyces cerevisiae yeasts]. / Nekotorye osobennosti konechnykh stadii biosinteza érgosterina u drozhzhei Saccharomyces cerevisiae.

A scheme of ergosterol cyclic intermediate transformations in S. cerevisiae has been proposed. It is based on the analysis of sterol composition in strains with mutant blocks of one or two reactions of enzymatic synthesis. Biochemical reactions of modification of cyclic part and side branch of sterol molecule are supposed to be carried out independently.

[Analysis of the products of ergosta-7,22-dien-3-beta-ol biotransformation by a Nocardia erythropolis culture]. / Analiz produktov biotransformatsii érgosta-7,22-dien-3-beta-ola kul'turoi Nocardia erythropolis.

The products of biotransformation by Nocardia erythropolis-402 of the microbial sterol ergosta-7,22-dien-3 beta-ol isolated from a Saccharomyces cerevisiae mutant were studied. The products were identified as ergosta-7,22-dien-3-one and ergosta-7,22-dien-17 alpha-ol-3-one by thin-layer chromatography, UV-spectrophotometry and mass-spectroscopy. It was found that the existence of 7-8 double bond slowed down the cleavage of the sterol side chain. The absence of 5-6 double bond prevents the formation of delta 4-3-ketosystem of coupled bonds.

[Yeast resistance to polyene antibiotics. VII. The interaction of the mutant alleles of the nystatin resistance genes in Saccharomyces cerevisiae]. / Rezistentnost' drozhzhei k polienovym antibiotikam. Soobshchenie VII. Vzaimodeistvie mutantnykh allelei genov nistatinustoichivosti u Saccharomyces cerevisiae.

The data on allele interactions of nystatin resistance genes are presented. It has been shown that the mutant phenotype of heteroallelic hybrids NYS1, NYS4 and, probably, NYS3 is strengthened. The intragenic complementation has been found in NYS2 gene, allowing to imply the multimeric structure of delta 8----delta 7 isomerase which is controlled by this gene.

[Genetico-ecological aspects of the use of nystatin-resistant yeast mutants in the yeast-Drosophila system]. / Genetiko-ékologicheskie aspekty ispol'zovaniia nistatinustoichivykh mutantov drozhzhei v sisteme drozhzhi-drozofila.

Nystatin-resistant strains of Saccharomyces cerevisiae with mutations in final steps of ergosterol biosynthesis have been studied in the ecologo-genetic yeast--drosophila system. It has been shown that yeast strains which belong to the Petersghoff genetic yeast stock collection, with mutations in NYSX, NYS2 and NYS3 genes, provide the development of Drosophila melanogaster. In the process of nutrition with yeasts having mutations in the NYS2 gene, the development of drosophila larvae takes place, due to ergosterol accumulated in the yeast cells. Drosophila melanogaster was shown to be unable to utilize the sterols with 8(9) and 24(25) double bonds.

[Yeast resistance to polyene antibiotics. VI. Isolation and biochemical analysis of strains of Saccharomyces cerevisiae yeasts with mutations in the 2 nystatin-resistance genes]. / Rezistentnost' drozhzhei k polienovym antibiotikam. Soobshchenie VI. Poluchenie i biokhimicheskii analiz shtammov drozhzhei Saccharomyces cerevisiae s mutatsiiami v dvukh genakh nistatinustoichivosti.

The comparative analysis of sterol content in the yeast Saccharomyces cerevisiae strains singly or doubly defective in nystatin resistance genes was carried out. The strains with two mutations in NYS genes were shown to accumulate the sterol mixture, similar to that of the parental singly defective mutant. This type of gene interaction allows to define the main biochemical order of reaction in ergosterol synthesis: methylation in C24 (NYS1), delta 8----delta 7 isomerization (NYS2), C5 (6) and C22 (23) desaturation (NYS3 and NYSX).

[Evaluation of the vitamin D activity of yeasts with altered sterol metabolism]. / Otsenka D-vitaminnoi aktivnosti shtammov drozhzhei s izmenennym metabolizmom sterinov.

The sterol content of Saccharomyces strains with altered ergosterol metabolism was studied by UV-spectrophotometry, thin-layer chromatography and chromatographic mass-spectroscopy. A technique for estimation of D-vitamin activity of the yeast strains is proposed. The irradiated biomass of the strains accumulated ergosta-5,7-dien-3 beta-ol and also cholesta-5,7,24-trien-3 beta-ol and cholesta-5,7,22,24-tetraen-3 beta-ol is characterized by high antirachitic activity.