Influence of Natural Polyphenols on Isolated Yeast Dipodascus magnusii Mitochondria.

The effect of stilbene polyphenols (resveratrol and pinosilvin) and flavonoids (dihydromyricetin, epigallocatechin, and dihydroquercetin) on producing the reactive oxygen species (ROS) due to cell respiration using the isolated mitochondria of the fungus Dipodascus (Endomyces) magnusii was studied. It was shown that the inhibition of the ROS generation with stilbenes is related to both the oxygen consumption inhibition and their antioxidant properties. The degree of manifestation of polyphenol antioxidant properties depended on the number of hydroxyl groups in a polyphenol molecule. Of the flavonoids tested, dihydromyricetin was most active in reducing the ROS generation, but its inhibitory effect on oxygen consumption by mitochondria was significantly lower as compared to that of the stilbenes. The data obtained show that the mechanism of reducing the ROS generation with polyphenols is associated with both the respiratory inhibition and their antioxidant properties.

A New Recombinant Strain of Yarrowia lipolytica Producing Encapsulated Phytase from Obesumbacterium proteus.

A new recombinant strain of Yarrowia lipolytica synthesizing encapsulated highly thermostable phytase of Obesumbacterium proteus, which is recommended for use as a premix component of feed compositions in animal husbandry, was obtained.

[Stress Resistance Mechanisms in the Indicator Fungi from Highly Radioactive Chernobyl Zone Sites].

Comparison of the levels of the protein carboxylic groups in response to peroxide stress revealed enhanced stress resistance in Purpureocillium lilacinum strains isolated from soils with high content of copper or radionuclides compared to the strains isolated from uncontaminated soils. While in background strains resistance to peroxide stress increased with glucose content in the medium increasing from 0.002 to 2%, the strains from radionuclides- or copper-contaminated soils did not exhibit this pattern. Respiratory activity and polyphosphate content were compared for radiation-resistant strain 1941 and strain SM from the area with zero radioactivity. For the protoplasts of strain 1941 isolated from the Chernobyl zone, elevated respiratory activity was revealed on the media with low glucose content. Under the control conditions, the content of inorganic polyphosphates (polyP) in strains 1941 and SM was the same. Under conditions of peroxide stress, only the background strain SM grown on the medium with low glucose concentration exhibited decreased levels of inorganic polyphosphates. Independent on glucose concentration in the medium, in both P. lilacinum strains, polyP content increased in the course of regeneration after peroxide stress.

[Redox Status of Extremophilic Yeast Yarrowia Lipolytica During Adaptation to pH-Stress].

In this study we investigated the activities of antioxidant enzymes (superoxide dismutases (SODs) and catalases (CATs)) and the ROS level in cells of Yarrowia lipolytica yeasts grown in a medium with different pH values (4.5, 5.5 and 9.0). It was shown that an increase in the cellular ROS level took place under both acid and alkaline conditions. The growth under extreme conditions was accompanied by a significant increase of SOD activity (by 2.5 times in the acid medium and by 4 times in the alkaline medium), but catalase activity did not change. A study of the electrophoretic profile of catalases showed the presence of three isoforms differing in inhibitor resistance. The electrophoretic profiles of SODs and their inhibitory analysis revealed there are two other isoforms, probably of mitochondrial origin, in addition to Cu and Zn SOD. The role of SOD in pH-adaptation of extremophilic Y. lipolytica yeasts is discussed.

[Influence of Oxygenated Derivatives of Linoleic and Linolenic Acids on the Formation of Conidia and Protoperithecia in Wild-Type and Photoreceptor Complex Mutants of Neurospora crassa].

The regulatory effect of two oxyderivatives of unsaturated fatty acids (oxylipins), 18-hydroxy-(9Z,12Z)-octadecadienoic acid (18-HODE) and 18-(9Z,12Z,15Z)-octadecatrienoic acid (18-HOTrE), on the sexual and asexual sporulation of wild-type Neurospora crassa strains and wc-1 and wc-1 mutants was studied. In the wild-type strain, 18-HODE, unlike 18-HOTrE, stimulated protoperithecia formation in the dark and in the light. In the same strain, the studied oxylipins influenced conidiagenesis only under illumination. 18-HODE stimulated and 18-HOTrE inhibited the conidia formation. Oxylipins had no effect on protoperithecia formation in photoreceptor complex mutants, which apparently indicated its involvement in signal transmission in N. crassa. The stimulating action of the studied oxylipins on conidiagenesis in wc-1 and the lack of action in wc-2 may indicate alternative signaling pathways of oxylipins in this process.

[Melanin pigments of fungi under extreme environmental conditions (review)].

This review is dedicated to the research on the functions of melanin pigments in fungi. The participation of melanin pigments in protection from environmental factors is considered. Data on the biosynthetic pathways and types of melanin pigments in fungi are presented.

[Fungal anthraquinones (review)].

The review is devoted to the characteristics of anthraquinones--a group of pigments of quinoid nature often found in fungi. The distribution of anthraquinones in fungi, the routes of their biosynthesis, and their biological activity are considered.

[Comparative analysis of respiratory activity in the wild type strain of Neurospora crassa and its photoreceptor complex mutants].

Cell respiratory activity of protoplasts obtained from the wild type of Neurospora crassa and photoreceptor complex WCC--white collar 1 (wc-1) and white collar 2 (wc-2)--mutants of Neurospora crassa strains was investigated. Respiration inhibition by KCN in the presence of 25 mM succinate was similar in all strains and did not exceed 83-85% against control. The significant induction of KCN-resistant respiratory pathway occurred under 1% glucose oxidation in wc-1 and wc-2 mutants if compared with the wild type strains. The inhibitors of the main (cytochrome) pathway of electron transfer in mitochondria-1 mM KCN and antimycin A (4 microg/ml)--blocked the respiration rate of the protoplasts from N. crassa wild type by 75%, while the cell respiration of wc-1 and wc-2 strains was suppressed by approximately 50%. The specific inhibitor of alternative oxidase--10 mM salicylhydroxamic acid (SHAM)-in combination with the blockers of mitochondrial electron transfer chain caused the total suppression of respiratory activity of protoplasts in all studied strains. It is supposed that an increase of KCN-resistance in WCC mutants under glucose oxidation is connected with alternative oxidase activation as the result of failure in reception and signal transduction of active oxygen species.

[A comparative investigation of adaptation to oxidative stress factors a strain of mycelial fungus Paecilomyces lilacinus from Chernobyl Atomic Energy Station and strains of the same species from territories with basic level of radioactive pollution].

An oxidative stress resistance in Paecilomyces lilacinus strain from Chernobyl Atomic Energy Station (ChAES) as well as in P. lilacinus strains from zones with control level of radioactive pollution has been studied. It was shown that radial growth rate of the colony of the ChAES strain in a range of glucose concentrations 0.002%; 0.2%; 0.5%; 1.0% showed maximum on the medium with 0.2% glucose. It was 1.5 times higher than growth rate of the control strains. Adaptation slowdown reaction has been found as a result of the first 10-30 min H2O2 treatment most profound in the ChAES (No 1941) strain. Under 10(-3) mol/l H2O2 growth of No 1941 resumed with 20% loss in growth rate. Cessation of growth of the control strain (No 10) was observed under these conditions. It has been shown that in the strain from ChAES zone adaptation to low glucose content in the medium (0.2%) was coupled with an increased resistance to oxidative stress.

[Stress factor-induced changes in the activity of antioxidant protective mechanisms in the wild type strain of Neurospora crassa and in its photoreceptor complex mutants].

The effect of stress factors (changes in oxygen content, temperature, and illumination) on superoxide dismutase (SOD) and catalase activity, as well as on the content of thiol and disulfide groups in low-molecular-weight compounds and proteins of Neurospora crassa mycelium was studied in the wild type strain and white collar-1 (wc-1) and white collar-2 (wc-2) mutants. Environmental stress factors induced the activation of both SOD and catalase, as well as an increase in the thiol level in the wild type strain of Neurospora crassa. In the wc-1 and wc-2 mutants, an increase in catalase activity and in the total thiol level was revealed; however, activation of superoxide dismutase was not observed. A decrease in the formation of disulfide bonds in the proteins of wc-1 and wc-2 mutants (as compared with the wild type strain) was recorded. These results indicate disrupted transduction in the WCC mutants of stress factor signals that promote ROS (reactive oxygen species) formation.

Reactive oxygen species in regulation of fungal development.

Reactive oxygen species (ROS) are formed by fungi in the course of metabolic activity. ROS production increases in fungi due to various stress agents such as starvation, light, mechanical damage, and interactions with some other living organisms. Regulation of ROS level appears to be very important during development of the fungal organism. ROS sources in fungal cells, their sensors, and ROS signal transduction pathways are discussed in this review. Antioxidant defense systems in different classes of fungi are characterized in detail. Particular emphasis is placed on ROS functions in interactions of phytopathogenic fungi with plant cells.

[Reactive oxygen species and the strategy of the antioxidant defense in fungi: a review].

The level of reactive oxygen species (ROS) in the cell regulates the growth and differentiation of the fungal organism. This review considers the pathways of generation of the primary ROS and the defense methods used by fungi and yeasts against them as well as the involvement of thiol compounds in the antioxidant defense of the fungal cell. It is demonstrated that the adaptation of fungi to oxidative stress is tightly connected with the redox-dependent changes in the activities of antioxidant defense components.

[Oxidative stress and cell differentiation in Neurospora crassa].

Environmental stress factors induce oxidative stress in fungi by increasing the intracellular concentrations of reactive oxygen species (ROS). In the mycelium, ROS act as signal molecules needed for cytodifferentiation at certain stages of the development of fungi. Generation of ROS in cells induces the activation of antioxidant protective mechanisms. The purpose of this communication is to analyze the role of ROS in light signal transduction, mediated in Neurospora crassa cells by the White Collar Complex.

[A comparative study of the components of the antioxidant defense system during growth of the mycelium of a wild-type Neurospora crassa strain and mutants, white collar-1 and white collar-2].

A comparative study of the changes in the components of the antioxidant defense system (ADS), the activity of superoxide dismutase (SOD) and catalase and the level of extractable SH-groups, during the growth of wild-type and mutant (white collar-1 and white colar-2) Neurospora crassa strains was performed. Oxidative stress developing during spore germination and upon the transition to a stationary growth phase was accompanied in all strains by an increase in the level of extractable SH-groups and SOD activity, whereas the total catalase activity decreased during growth. However, in contrast to the wild-type strain, the activity of the catalase in the mutant strains wc-1 and wc-2 slightly increased upon the transition to the stationary phase. In the wc-2 mutant, SOD activity and the level of extractable SH-groups in the exponential growth phase were always lower than in the wild-type and wc-2 strains. The role of wc-1 and wc-2 genes in the level regulation of reactive oxygen species is discussed.

[Participation of beta-carotene in antioxidant defense of bacterial cells]. / Uchastie beta-karotina v antioksidantnoi zashchite bakteral'noi kletki.

The effect of recombinant beta-carotene on the resistance of E. coli culture to menadione and paraquat was studied. The presence of beta-carotene in the E. coli cell significantly prevented an increase in the activity of superoxide dismutase induced by redox mediators but had no effect on the culture growth. The findings suggested the involvement of beta-carotene in the cell defense against oxidative stress.

[Initial stages of trisporic acid synthesis in Blakeslea trispora]. / Nachal'nye étapy sinteza trisporovykh kislot u Blakeslea trispora.

Biotransformation of beta-carotene with enzyme preparations isolated from the mycelium of Blakeslea trispora resulted in the formation of its hydroxylated metabolite and apocarotenals, products of oxidative degradation of this compound. By spectral, chromatographic, and chemical properties, the beta-carotene derivative was identified as 4-hydroxy-beta-carotene (isocryptoxanthine). One of the products of oxidative degradation of beta-carotene, beta-apo-13-carotenone, underwent modification in the presence of enzyme preparations from Blakeslea trispora with the formation of trisporic acid precursors. It should be emphasized that beta-apo-13-carotenone transformation proceeded more rapidly than beta-carotene oxidation by carbon in the 4-position. Our findings suggest that under conditions of oxidative stress, oxidative degradation of beta-carotene into beta-apo-13-carotenone leads to the formation of considerable amounts of trisporic acids.

[Superoxide dismutase and catalase activities in carotenoid-synthesizing fungi Blakeslea trispora and Neurospora crassa under the oxidative stress]. / Aktivnost' superoksiddismutazy i katalazy u karotinoidsinteziruiushchikh gribov Blakeslea trispora i Neurospora crassa v usloviiakh okislitel'nogo stressa.

The addition of menadione into the medium during cultivation of Neurospora crassa in the dark activated its constitutive superoxide dismutase. Exposure to light not only activated superoxide dismutase and catalase, but also increased the content of neurosporaxanthin. Superoxide dismutase activity in the mixed (+/-) mycelium of Blakeslea trispora synthesizing beta-carotene in the dark was much lower than that in Neurospora crassa. The superoxide dismutase activity further decreased in oxidative stress. The catalase activity decreased with an increase in the content of beta-carotene. Our results indicate that neurosporaxanthin possesses photoprotective properties in Neurospora crassa. In Blakeslea trispora (+/-) fungi, this compound acts as a major antioxidant during inactivation of enzymes that detoxify reactive oxygen species.