Screening of thermotolerant yeasts as producers of superoxide dismutase.

A screening procedure for highly thermostable yeast superoxide dismutase was developed. Growth yields at various temperatures were estimated for ten mesophilic and thermotolerant strains, belonging to the genera Saccharomyces, Kluyveromyces and Pichia. Higher yields at 45 degrees C were obtained for K. lactis 90-3 and 90-4. A correlation between the ability to grow at higher temperature and the thermostability of the superoxide dismutase enzyme synthesized was observed. A comparison of the operational stability of the superoxide dismutase of all tested strains suggests that the enzyme of K. lactis strains was more thermostable than that of the other tested microorganisms.

[Assimilation of n-alkanes with a varying length of the carbon chain by the yeast Candida guilliermondii]. / Assimiliatsiia n-alkanov razlichnoi dliny uglerodnoi tsepi drozhzhhami Candida guilliermondii.

Using radioactive tracers, the effect of n-alkanes with a varying length--C16-C25--of the carbon chain on the rate of yeast growth and the ratio of major chemicals in their biomass was studied. The change in the level of n-alkanes accumulated by the yeast during carbon starvation was determined. No differences in the rate of metabolization of 1-14C-octadecane, 1,2-3H-hexadecane, and 13-14C-pentacosane were found. During 3 hour incubation the cell losses of C25, C18 and C16 amounted to 35.0, 33.0 and 38.1 microgram alkane/mg yeast, respectively. The intensity of yeast growth in the accumulative culture on dispersed n-alkanes with different molecular weights was similar. The specific formation of CO2 during the lag-phase by the yeast cultivated C18 was larger than on C23 or C25. The lipid content in the yeast grown on C18 was 3 times greater than in those grown on C22. The difference was made by an increased content of triglycerides and waxes.

[The cardioprotective action of preparations of biotechnological cytochrome c in acute myocardial ischemia]. / Kardioprotektornoe deistvie preparatov biotekhnologicheskogo tsitokhroma c pri ostroi ishemii miokarda.

The cardioprotective effect of cytochrome c preparations was evaluated according to the test for restriction of the size of the myocardial infarct and the effect on the course of acute myocardial ischemia in acute experiments on dogs. Cytochrome c of biotechnological and animal origin and hemtetradecapeptide caused a marked decrease in the size of the myocardial necrosis in experiments on rats: from 68 +/- 4.3% in the control to 32 +/- 3.4, 46 +/- 8.3 and 44 +/- 4.7%, respectively. In dog experiments the cytochrome c agents reduced the intensity of dp/dt decline and decreased the collateral coronary blood flow in acute myocardial ischemic. They produced a beneficial effect on heart bioenergetics, namely, reduced the lactate level in blood flowing from the zone of the ischemia and glucose consumption by the ischemic myocardium. The cardioprotective effect of biotechnological cytochrome c hemtetradecapeptide was practically identical to the effect of the enzyme of animal origin.

[The effect of cytochrome c preparations on the autoregulation of the cerebral blood flow in ischemia]. / Vliianie preparatov tsitokhroma c na autoreguliatsiiu mozgovogo krovotoka v usloviiakh ishemii.

The effect of animal cytochrome C (Ca), biotechnological cytochrome (Cb) and its hemtetradecapeptide (HTDP) on cerebral blood flow autoregulation during rapid decrease of systemic arterial pressure (SAP) was studied in acute experiments on rats. Cytochrome C preparations caused no effect on the autoregulatory responses of the cerebral vessels in animals with normal cerebral circulation. Injection of 5 mg/kg Ca and Cb and 0.8 mg/kg HTDP promoted restoration of the phenomenon of cerebral blood flow autoregulation in ischemic brain damage in change of SAP from 120 to 60 mm Hg. Prophylactic injection of 20 mg/kg Ca and Cb and 3.3 mg/kg HTDP prevented cerebral blood flow autoregulation disturbance caused by transitory brain ischemia.

[The effect of cytochrome c preparations on the cerebral circulation in cerebral ischemia]. / Vliianie preparatov tsitokhroma c na mozgovoe krovoobrashchenie pri ishemii mozga.

Biotechnological cytochrome c, heme-tetradecapeptide (HTDP) and animal cytochrome c were studied for their effects on intact and brain ischemic rats. In the latter case, the compounds were administered before ischemia induction and 15 min after artery ligation. It was found that the cytochrome c preparations did not virtually affect the cerebral circulation in intact rats. In cerebral ischemia, the cytochrome C preparations increased circulation, showing their more profound effects in case of preadministration of the drugs. The dose-independent effects of HTDP may be associated with the higher transmembranous permeability and the saturation phenomenon of this compound.

[14C incorporation into lipid fractions of yeast Candida quilliermondii during growth in the presence of different carbon sources]. / Vkliuchenie C14 v lipidnye fraktsii drozhzhei Candida guilliermondii pri vyrashchivanii kletok v prisutstvii razlichnykh istochnikov ugleroda.

Kinetics of 14C incorporation into lipid fractions of yeast C. quilliermondii from 1-14C-octadecane and 1,2-14C-acetic acid is studied. Considerable differences, revealed in kinetics and the rate of 14C incorporation into lipid fractions depending on the lipid precursors, draw to the conclusion that the lipid synthesis from octadecane and acetic acid can occur through different pathways. The absence of the competition under the carbon influx into lipid fraction also suggests, that the lipid synthesis from ocetate and carbohydrate takes place simultaneously through two different pathways, which are spatially uncoupled in cell. A presence in yeast cells of two glyoxylate shunts is proposed, which are spatially uncoupled and specific to acetyl residues of different origins.

[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.

[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.