[Isolation of yeast nuclei and characteristics of their lipid composition]. / Vydelinie i kharakteristika lipidnogo sostava iader iz drozhzhei.

Intact nuclei of a high purity degree were isolated from Candida utilis protoplasts, and their lipid content and composition were determined.

[Metabolic transformation of labelled exogenous fatty acids by fungal cultures of the family Entomophthoraceae]. / Metabolicheskie prevrashcheniia ékzogennykh mechenykh zhirnykh kislot kul'turami gribov semeistva Entomophthoraceae.

Entomophthora coronata 1932 and E. conica 1716 are quite different in their fatty acid composition and the unsaturation degree of synthesized lipids. The cultures were used as models to study metabolic transformations of exogenous 14C-labeled acetic, palmitic, stearic and oleic acids as well as to compare the activities of the synthetase and desaturase enzyme complexes. The cultures were capable of transforming exogenous acetic and fatty acids into polyunsaturated arachidonic acid. E. coronata 1932 whose lipids mainly contain fatty acids with a short chain could metabolize unsaturated oleic acid to yield polyene fatty acids. However, this culture metabolized exogenous acids at a far lower rate as compared with E. conica 1716. The high content of saturated fatty acids with a short chain in the lipids might be due to the specific action of the synthetase complex and to the low activity of the desaturation enzymes. It has been demonstrated for the first time that exogenous oleic acid is converted at a high rate by the cells into arachidonic acid, a precursor of prostaglandin compounds.

[Compartmentalization of metabolism of spatially-delimiting amino acid pools of yeast cells]. / Kompartmentalizatsiia obmena prostranstvenno-razgranichennykh fondov aminokislot drozhzhevoi kletki.

The spatially different amino acid pools (i.e. cytoplasmic, vacuolar and mitochondrial) of yeast cells are metabolically compartmentalized. The accumulation of amino acids in these pools occurs at different rates; the highest rates are observed for glutamate and alanine. The former is predominantly accumulated in the cytoplasm, the latter--in the vacuoles. The renewal rates of the amino acid pools are also different. Each of them contains at least two subpools, readily convertible and relatively stable ones. The readily convertible subpools of the cytoplasmic and mitochondrial pools predominantly contain glutamate, aspartate, valine and alanine; that of the vacuolar pool--alanine. The bulk of the readily convertible alanine subpool (67%) is localized in the vacuoles, that of glutamate and aspartate (85 and 68%, respectively)--in the cytoplasm.

[Dynamics of metabolism of different compartments of amino acid pools in yeast cells]. / Issledovanie dinamiki obmena prostranstvenno-razgranichennykh aminokislotnykh fondov drozhzhevoi kletki.

The incorporation of [14C] into the amino acid pools located in different cell compartments of the yeast Candida tropicalis was studied. The rate of [14C]-labelled amino acids incorporation into the cytoplasm is 2 times higher than that in the vacuoles and 10 times higher than that in mitochondria. The amino acid pools under study are heterogenous in terms of generation rate: each of them contain at least two minor carbon pools, i.e. rapidly regenerating and relatively stable ones, whose ration is different. While the rapidly regenerating part of the amino acid pools of the protoplasts makes up to about 8.8% of total carbon pool, that of the mitochondrial pool makes up to 17% and the vacuolar one is only 2% of total carbon of the amino acid pools in these organelles.

[Heterogeneity of the amino acid pool of the yeast cell with respect to the rate of carbon reduction]. / Geterogennost' aminokislotnogo gonda drozhzhevoi kletki v otnoshenii skorosti obnovleniia ugleroda.

A new procedure for estimating the correlation between the metabolic and relatively stable carbon depots in the amino acid pool of the yeast cell is proposed. It has been shown that the metabolic carbon depot of the amino acid pool of the yeast cell utilizing glucose as the only carbon source makes up to 9.3% of the total carbon of this pool or 0.92% of total carbon of the cell.

[Electrophoretic characteristics of the protein of yeast lipid granules]. / Elektroforeticheskaia kharakteristika belka lipidnykh granul drozhzhei.

The proteins from the membranes of lipid granules, the plasmalemma and the membranes of the endoplasmic reticulum isolated from Candida tropicalis cells were analyzed using electrophoresis in polyacrylamide gel. The electrophoretic spectra of the proteins from these membranes were quite different. It has been proved experimentally that lipid granules from yeast cells growing on n-alkanes and containing large amounts of n-alkanes are not derivatives of the pinocytozing plasmalemma. The membranes of lipid granules are presumed to be formed in the cell de novo upon accumulation of substances of the lipid nature.

Investigation of the turnover of the carbon of organic fractions of yeasts in the logarithmic phase of growth.

An investigation of the isotopic exchange (turnover) of carbon among the basic groups of organic substances of yeast biomass (proteins, polysaccharides, lipids, free amino acids, carbohydrates, and organic aicds) showed that in the presence of a carbon source and all the necessary nutrient elements in the logarithmic phase of growth of the culture, the bulk of the organic substances of the cell are extremely stable. Under these conditions, no appreciable utilization of the carbon of low-molecular-weight pools, nor any significant degradation of high-molecular-weight substances can be detected. Nor was there any redistribution of carbon-14 among individual components of the fraction of free amino acids and lipids. It was shown that the fraction of exchangeable carbon of the biopolymers of mature cells, like the fraction of the exchnage pool of low-molecular-weight substances, does not exceed 10% of the total carb-n of these substances. It is suggested that there is no mixing of the old and newly synthesized low-molecular-weight carbon pools in the parent cell, and all the components of the biomass of the daughter cells are synthesized chiefly from the carbon of the substrate.

[Comparative study of the dynamics of carbohydrate metabolism in the growth of Candida tropicalis yeasts on n-octadecane and glucose]. / Sravnitel'noe issledovanie dinamiki uglerodnogo obmena pri roste drozhzhei Candida tropicalis na n-oktadekane i gliukoze.

The dynamics of carbon metabolism was studied in Candida tropicalis growing on 14C-labeled n-octadecane and glucose by means of the technique of radioactive indicators. The kinetics of incorporation of 14C into the main groups of organic substances in the cell (proteins, nucleic acids+polysaccharides, lipids, free amino acids, organic acids, free carbohydrates+nucleotides) revealed differences in the rate of their synthesis and accumulation. The general features and the major differences in the pathways of carbon metabolism depended on the nature of a carbon substrate. If the yeast used n-octadecane as a source of carbon, the rate of synthesis of the lipid fraction was higher, and the ratio between its components changed as well as the rates of their synthesis.

[Metabolic products of hydrocarbon-oxidizing strains of Mycococcus lactis and Pseudomonas fluorescens and their influence on culture growth]. / Produkty metabolizma uglevodorodokisliaiushchikh shtammov Mycococcus lactis i Pseudomonas fluorescens i ikh vliianie na razvitie kul'tur.

The effect of concentrations of organic acids in the cultural broth on growth was studied with the strains of Mycococcus lactis and Pseudomonas fluorescens oxidizing hydrocarbons. The ratio between the acid and neutral fractions in the cultural broth of Mycococcus lactis was also investigated as well as their action on the bacterial growth. Mycococcus lactis growing on paraffin was found to produce acid and neutral products at a ratio of 1:2. The acid and neutral products of metabolism produced different action on the growth of the carbohydrate oxidizing bacteria. The acid products inhibited the growth at a concentration of organic acids in the medium above 500 mg/litre. The neutral products were partily assimilated by Mycococcus lactis.

[Isolation and characteristics of the lipid granules of Candida tropicalis yeasts]. / Vydelenie i kharakteristika lipidnykh granul drozhzhei Candida tropicalis.

Preparative isolation of lipid granules from the protoplasts of Candida tropicalis was conducted by a technique of flotation in a stepwise density gradient. Parameters were selected for decomposing the protoplasts under hypotonic and isotonic conditions which made it possible to preserve the lipid granules being isolated intact, as well as parameters of a density gradient and centrifugation. The specific content of lipids, proteins and low molecular weight compounds was assayed using labeled compounds in the lipid granules which were isolated from yeast cells cultivated on various carbon substrates (1-6(-14C)-glucose and 1(-14C-octadecane). The lipid composition of the spherosomes was determined. If the yeast was grown on glucose, lipids localized in the lipid granules were represented mainly by triglycerides whose carbon constituted 69 per cent of the total lipid carbon. If it was cultivated on n-octadecane, these lipids were represented by hydrocarbons (51 per cent) and triglycerides (22 per cent). The structures isolated possessed a small lipase activity. The specific lipase activity of the lipid granules was lower by 16 per cent than that of the cell protoplast.

[Studies of the primary distribution kinetics of n-alkane oxidation products according to morphological components of the yeast cell]. / Issledovanie kinetiki pervichnogo raspredeleniia produktov okisleniia n-alkana po morfologicheskim komponentam drozhzhevoi kletki

Incorporation of 14C into various classes of lipids localized in the cell walls, large membranes, mitochondria and microsomes of yeast cells was studied during their incubation with 1-14C-octadecane. Cell structures were found to differ considerably by the kinetics and level of accumulation of 14C-components of the lipid fraction. Waxes and triglycerides prevail during primary accumulation of 14C-lipids in the large membranes and cell walls. Synthesis of these compounds is presumed to play an important role in the course of primary transformation of n-octadecane.

[Isolation of vacuoles from Candida tropicalis]. / Vydelenie vakuolei iz drozhzhei Candida tropicalis

Intact vacuoles were isolated from the homogenate of the Candida tropicalis protoplasts by flotation in a stepwise gradient of phycoll density. New parameters of protoplast decomposition in hypotonic and isotonic conditions yielding intact vacuoles have been found, as well parameters of density gradient and conditions of centrifugation which differ essentially from parameters used by other authors for isolating the vacuoles from the Saccharomyces cells. The purity of the vacuole preparations was confirmed by using enzymes, light and electron microscopy. The specific content of the carbon of protein, lipids, and free amino acids in the vacuoles and protoplasts of the yeast cells cultivated on 14C-labelled glucose was determined by the radioindicator technique.

[Primary distribution of n-alkane through the structures of yeast cells]. / Pervichnoe raspredelenie n-alkana po strukturam drozhzhevykh kletok

When n-alkane enters the cells as a result of molecular sorption and diffusion, it is distributed within all membrane structures of the cell (microsomes, mitochondria, membranes, vacuoles, cytoplasmic membranes, and cell walls). Sorption of n-alkane by all these structures in vivo comes at equilibrium after incubation of the cells with n-alkane during 3-4 min. Accumulation of the hydrocarbon in the morphological fractions of the cell depends on its concentration in the incubation medium. Isotherms of the sorption are convex curves. Sorption power, maximum sorption capacity, affinity and strength of the bonds with the hydrocarbon differ among the membrane structures of the cell. The maximum capacity of sorption of n-alkane by the structures does not correlate with the content of lipids and phospholipids in the structures. Sorption of n-alkanes is presumed to depend on the structural organization of lipids in the morphological fractions.

[Isolation and characteristics of the cellular structures of Candida tropicalis]. / Vydelenie i kharakteristika kletochnykh struktur Candida tropicalis

Using the method of radioactive indicators, the specific content of proteins, lipids, total phosphorus, and lipid phosphorus was estimated in the morphological cell fractions of Candida tropicalis after growth in a liquid mineral medium containing n-octadecane as a source of carbon. The morphological cell fractions were produced by means of differential centrifuging. The following comparatively pure fractions were obtained simultaneously: soluble fraction, microsomes, mitochondria, large membranes, and cell walls.

[Assimilation of 1-14-C-octadecane by the (-)4 strain of Blakeslea trispora]. / Issledovanie assimiliatsii 1-14-C-oktadekana (-)4 shtammom Blakeslea trispora

The assimilation of 1-14C-octadecane by the (-) 4 strain of Blakeslea trispora was studied, i.e. the kinetics of 14CO2 evolution and the distribution of the label in the biomass, proteins, lipids, and water-soluble products of the fungus. B1. trispora oxidized octadecane even in the presence of glucose in the medium. The distribution of the label between the protein and lipid fractions was different when the fungus was grown on octadecane or on a mixture of octadecane with glucose. After 6 hours of the incubation the content of the label in proteins (the experiment with 1-14C-octadecane as a carbon source) was 33 percent, and 60 percent in lipids. In the experiment with a mixture of glucose and hydrocarbon, the content of the label was 8 percent in proteins and 95 percent in lipids. These results show the participation of n-alkane and the products of its oxidation in the metabolism of Blakeslea trispora.