Melanin complex of the fungus Inonotus obliquus

The fungus Inonotus obliquus (Pers.) Pil. synthesised high-molecular-weight phenolic pigments that were assigned to melanins according to their physicochemical properties. It was showed that copper ions (0.008%), pyrocatechol (1.0 mM), and tyrosine (20.0 mM) stimulated the melanogenesis. The production of melanin correlated with the synthesis of o- and p-diphenoloxidases. The fungal melanin had strong antioxidant and genoprotective effects.     

Melanin pigments of the fungi Paecilomyces variotii and Aspergillus carbonarius

Pigments synthesized by micromycetes Paecilomyces variotii and Aspergillus carbonarius are true melanins. Copper ions and bicyclic phenolic compounds stimulated melaninogenesis, whereas benzotriazole inhibited this process. Precursors of melanin pigments were obtained and identified. p-Hydroxybenzoic acid was shown to be the main product of melanin degradation. Melanins of these fungi are concluded to belong to the dihydronaphthalene group.     

The Carbohydrates of Submerged Mycelium of Xylotrophic Basidiomycetes

It was demonstrated that the total carbohydrate content in the submerged mycelium of xylotrophic basidiomycetes falls into the range of 34.66–57.57%. Free carbohydrates of the cell cytosol amounted to 14.52–28.64%; structural carbohydrates, to 20.14–32.70%. Qualitative composition of carbohydrates was studied, which allowed for attribution of structural polysaccharides to hetero- and homoglycans with - and -glycoside bonds.     

The carbohydrates of submerged mycelium of xylotrophic basidiomycetes

It was demonstrated that the total content of carbohydrates in the submerged mycelium of xylotrophic basidiomycetes falls into the range of 34.66-57.57%. Free carbohydrates of the cell cytosol amounted to 14.52-28.64%; structural carbohydrates, to 20.14-32.70%. Qualitative composition of carbohydrates was studied, which allowed for attributing structural polysaccharides to hetero- and homoglycans with beta- and alpha-glycoside bonds.     

The nature of melanin pigments from some micro- and macromycetes

New inhibitors of melanin formation by micromycetes Aspergillus carbonarius, Alternaria alternata, and Paecilomyces variotii and basidiomycetes Inonotus obliquus and Phellinus robustus were found. Precursors of melanin pigments were isolated and identified. p-Hydroxybenzoic acid was identified among the products of alkaline degradation of melanin formed by micromycetes, whereas in the case of macromycetes this was protocatechuic acid. Therefore, melanins of the former were found to belong to the dihydronaphthalene group, whereas those of the latter belong to catechols.     

Melanin pigments from the fungiPaecilomyces variotii andAspergillus carbonarius

Pigments synthesized by the micromycetesPaecilomyces variotii andAspergillus carbonarius are true melanins. Copper ions and bicyclic phenolic compounds stimulated melaninogenesis, whereas benzotriazole inhibited this process. Precursors of melanin pigments were obtained and identified.p-Hydroxybenzoic acid was shown to be the main product of melanin degradation. Melanins of these fungi are concluded to belong to the dihydronaphthalene group.     

Antioxidant properties of fungal melanin pigments

Fungal melanin pigments were shown to display a high antioxidant activity. An increase in the number of methyl substituents in benzidine molecules of melanins obtained from micromycetes and macromycetes was accompanied by a decrease in the efficiency of inhibition of peroxidase-mediated oxidation. Melanins were found to have considerable gene-protecting properties. Pigments isolated from macromycetes and applied at a much lower concentration than those obtained from micromycetes prevented damage to bacteriophage-λ DNA induced by products of peroxidase-mediated degradation of aminobiphenyls.     

Alu-DNA repeat-binding protein p68 is a part of Alu-RNA containing alpha-RNP.

An Alu-DNA repeat-binding protein with a molecular mass of 68 kDa (p68) is identified in the somatic human cell nucleoplasm. Gel mobility shift assay (GMSA), South-western blotting and affinity purification on DNA attached to the carrier were used in the identification. GMSA revealed multiple complexes with the exponential dependence of their relative mobility. A narrow binding site of the p68 was revealed using synthetic oligonucleotides. It is located between the A-box and B-box of the RNA polymerase III promoter and is identical to that reported for the Alu-binding protein from human spermatozoids. The same narrow binding site, the similarity of the isolation procedure from germ and somatic cells, and similar binding properties and molecular masses suggest homology of the two proteins. Antibodies raised against Alu-protein complexes led to hypershift of the complexes in GMSA and stained p68 in active fractions in human spermatozoids and in Alu-RNA-containing alpha-RNP particles. Immunofluorescence of a HeLa cell monolayer revealed an intranuclear dot pattern with the dots corresponding to euchromatin areas and some dots located at the cell periphery in the cytoplasm. alpha-RNP particles bound Alu-DNA in vitro and contained p68 as shown using the immunogold procedure. Alu-DNA binding activity was revealed in cytoplasm as well as in nucleoplasm. The possible nature of the main Alu-DNA binding protein and its involvement in the particle structure are discussed.     

Polysaccharides of <Emphasis Type="Italic">Ganoderma lucidum</Emphasis>: Factors affecting their production

The conditions of polysaccharide production by the fungus Ganoderma lucidum were optimized. The maximal yield of endopolysaccharides and exopolysaccharides was observed at 25–30°C, initial pH of culture medium 4.0–6.0, and at a C:N ratio of 18:1 and 25:1, respectively. The greatest yield of mycelium was reached at a more intensive aeration, and the maximal yield of polysaccharides was observed at a less intensive aeration. The optimal ratio between fungus growth and polysaccharide production was observed at 100 rpm and an aeration of 1.0– 1.5 1/1 medium·min.Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 2, 2005, pp. 194–199.Original Russian Text Copyright © 2005 by Babitskaya, Shcherba, Puchkova, Smirnov.     

Antioxidant activity in fungi degrading lignocellulose substrates

Considerable differences in lignin degradation by fungi of two ecological groups have been revealed. Xylotrophs cause a twofold decrease in the molecular weight of lignin. The degrading activity of saprotrophs is insignificant. Xylotrophs demethoxylate and oxidize lignin more rapidly than saprotrophs, showing a higher level of antioxidant activity. As follows from the comparison of the degrading and antioxidative effects, measurement of the antioxidant activity can be used in screening of fungi for the ability to degrade lignocellulose substrates.