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In 1992 a 120 km long section of the Danube river, part of the border line between Hungary and Slovakia, was diverted into a new riverbed to put into operation the Gabčikovo (Bős-Nagymaros) Hydropower Plant. To follow up the environmental changes a monitoring system in the Szigetköz region, seriously affected by the diversion of the river, was established by the Hungarian Academy of Sciences. Results of the bryological monitoring work, conducted in the river branches are presented in this article. Today, the species composition of the aquatic-riparian bryophyte vegetation living in the various sections of the Szigetköz branch-system is different from that of 1991–1992. The abundance-frequency values of aquatic species have decreased, while the proportions of mesophilous long-lived species and short-lived bryophytes have increased. The changes of water requirement spectra of bryophyte vegetation and the growing importance of certain species groups indicate that the ecological conditions became drier. Apparently, the water supply system operated from 1995 provides insufficient amount of water and is inadequate to stop (and even less so to reverse) the environmental changes that took place in the branch-systems.

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The mortality rates of fungal infections that affect the central nervous system are high in consequence of the absence of effective antifungal drugs with good penetration across the blood-brain barrier and the blood-cerebrospinal fluid barrier. In the present work in vitro antifungal activities of three good penetrating non-antifungal drugs (amantadine hydrochloride, R-(-)-deprenyl hydrochloride, valproic acid sodium salt) and their combinations with three antifungal agents (amphotericin B, itraconazole, terbinafine) were tested with broth microdilution method against eight fungal isolates belonging to Zygomycetes (Lichtheimia corymbifera, Rhizomucor miehei, Rhizopus microsporus var. rhizopodiformis, Saksenaea vasiformis) and Aspergillus genus (A. flavus, A. fumigatus, A. nidulans, A. terreus). These are known to be possible agents of central nervous fungal infections (CNFI). When used alone, the investigated nonantifungal drugs exerted slight antifungal effects. In their combinations with antifungal agents they acted antagonistically, additively and synergistically against zygomyceteous isolates. Primarily antagonistic interactions were revealed between the investigated drugs in case of Aspergilli, but additive and synergistic interactions were also observed. The additive and synergistic combinations allowed the usage of reduced concentrations of antifungal agents to inhibit the fungal growth in our study. These combinations would be a basis of an effective, less toxic therapy for treatment of CNFI.

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Intensification of land use in the last few decades resulted in an increased rate of fragmentation of natural forest habitats. With decreased patch size but increased total borderline length the influence of the surroundings also increased. The extent of influence is especially crucial where the forest stands are adjacent to agricultural lands. We studied the vegetation (cover) and seed bank (soil samples, seedling emergence) along adjacent stands of an abandoned vineyard and edge and interior of an oak forest community (Quercetum petraeae-cerris) widespread in Central-Europe, using five transects (16 m2 plots along each transect). We asked the following questions: (i) How do vegetation and seed bank composition differ between the vineyard and forest interior and (ii) which weeds are able to penetrate into the forest herbaceous understorey vegetation and seed banks from the vineyard? In total, 15 phanaerophytes and 147 herbs were detected. Negatively associated with canopy shading, herb cover proved the lowest in the forest inferior. Few weeds and other ruderals recorded in vineyard penetrated into the forest interior. Mean seed density decreased one order of magnitude from the vineyard to the forest interior (from 20,831 to 2,159 seed/m2). The seed banks of the abandoned vineyard and edge and forest interior were dominated by ruderals, but decreasing proportion of weeds was detected from the vineyard to the forest interior. Characteristic forest herbs possessed at most sparse seed banks. Our results suggest that high canopy cover mitigates the negative impact of surrounding weedy vegetation on the forest herb layer. Therefore, the effect of surroundings is detectable mostly in the seed banks. We can assume that the formation of an increased ruderal herb cover can be foreseen if canopy opens, because the local propagule sources of forest species are missing from vegetation and soil seed banks.

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A total of 126 bryophyte taxa (12 liverworts and 114 mosses) were collected in the Ibar gorge and its surroundings. The climate of the gorge receives Mediterranean influence, hence almost one fourth part of the species found are Mediterranean, sub-Mediterranean, or sub-Atlantic elements. Several rare species in Serbia and in the Balkans can be found in the territory (e.g. Bryum gemmiferum, Dialytrichia mucronata, Didymodon nicholsonii, Grimmia lisae, Gymnostomum viridulum, Hygroamblystegium humile, Orthotrichum obtusifolium, Syntrichia latifolia). One species (Buxbaumia viridis) is included in the Bern Convention and the European Union Habitats and Species Directives. The Ibar gorge maintains a unique bryophyte assemblage due to the serpentine bedrock and continental, Mediterranean climatic influence, which are the main characteristics of the region.

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Acta Biologica Hungarica
Authors: E. Horváth, G. Papp, Z. Gazdag, J. Belágyi, Á. Blaskó, J. Deli, Cs. Vágvölgyi, and M. Pesti

A carotenoid-less Phaffia rhodozyma mutant (MCP 325) exhibited significantly higher resistance to oxidative stressors such as menadione, H2O2 and K2Cr2O7 than its astaxanthin-producing parental strain (MCP 324). The absence of carotenoids in the mutant did not explain this phenomenon. The cause of the decreased superoxide, hydroxyl radical and glutathione contents, the increased peroxide concentration and the elevated specific activity of catalase under uninduced conditions may be a second mutation. Peroxide treatment induced specific catalase activity in the mutant but not in the parental strain. Regulation of these processes led to the result that, in spite of the mutations, the two strains exhibited the same multiplication rate and generation time.

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Extracellular β-glucosidase activity of 94 strains, representing 24 species of the genera Gilbertella, Mucor, Rhizomucor , and Rhizopus was evaluated in submerged culture and under solid state fermentation on wheat bran. Gilbertella persicaria G1 isolate showed the highest activity (70.9 U ml −1 ) followed by other Gilbertella (58.6–59.0 U ml −1 ) and Rhizomucor miehei isolates (29.2–42.0 U ml −1 ). Optimum temperature for enzyme production was 25 °C for Gilbertella and Mucor , and 30 °C for Rhizomucor and Rhizopus strains. Enzymes of R. miehei strains proved to be thermotolerant preserving up to 92.8% residual activity after heating to 75 °C in the presence of cellobiose substrate. Enzymes of Mucor racemosus f. chibinensis, R. miehei and Rhizopus microsporus var. oligosporus strains were activated at acidic condition (pH 4). Glucose was a strong inhibitor for each fungal β-glucosidase tested but some of them showed ethanol tolerance up to 20% (v/v). Ethanol also activated the enzyme in these strains suggesting glycosyl transferase activity.

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Acta Biologica Hungarica
Authors: Eszter Virág, Á. Juhász, R. Kardos, Z. Gazdag, G. Papp, Ágota Pénzes, M. Nyitrai, Cs. Vágvölgyi, and M. Pesti

Interaction of primycin antibiotic with plasma membrane, and its indirect biological effects were investigated in this study. The antifungal activity of primycin against 13 human pathogenic Candida ATCC and CBS reference species and 74 other Candida albicans clinical isolates was investigated with a microdilution technique. No primycin-resistant strain was detected. Direct interaction of primycin with the plasma membrane was demonstrated for the first time by using an ergosterol-producing strain 33erg + and its ergosterol-less mutant erg-2. In growth inhibition tests, the 33erg + strain proved to be more sensitive to primycin than its erg-2 mutant, indicating the importance of the plasma membrane composition in primycin-induced processes. The 64 μg ml−1 (56.8 nM) primycin treatment induced an enhanced membrane fluidity and altered plasma membrane dynamics, as measured by steady-state fluorescence anisotropy applying a trimethylammonium-diphenylhexatriene (TMA-DPH) fluorescence polarization probe. The following consequences were detected. The plasma membrane of the cells lost its barrier function, and the efflux of 260-nm-absorbing materials from treated cells of both strains was 1.5–1.8 times more than that for the control. Depending on the primycin concentration, the cells exhibited unipolar budding, pseudohyphae formation, and a rough cell surface visualized by scanning electron microscopy.

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This work focuses on the comparative analysis of the effects of two cyanobacterial toxins of different chemical structure cylindrospermopsin (CYN) and microcystin-LR (MC-LR) on the white mustard (Sinapis alba L.) seedlings. Both cyanotoxins reduced significantly the fresh mass and the length of cotyledons, hypocotyls and main roots of seedlings in a concentration dependent manner. For various mustard organs the 50% inhibitory concentration values (IC50) of growth were between 3–5 μg ml−1 for MC-LR and between 5–10 μg ml−1 for CYN, respectively. Cyanotoxins altered the development of cotyledons, the accumulation of photosynthetically active pigments and anthocyanins. Low MC-LR concentrations (0.01 and 0.1 μg ml−1) stimulated anthocyanin formation in the cotyledons but higher than 1 μg ml-1 MC-LR concentrations strongly inhibited it. The CYN treated chlorotic cotyledons were violet coloured in consequence of high level of anthocyanins, while MC-LR induced chlorosis was accompanied by the appearance of necrotic patches. Necrosis and increases of peroxidase enzyme activity (POD) are general stress responses but these alterations were characteristic only for MC-LR treated mustard plants. These findings provide experimental evidences of developmental alterations induced by protein synthesis and protein phosphatase inhibitory cyanotoxins (CYN and MC-LR) in a model dicotyledonous plant.

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Cereal Research Communications
Authors: Z. Áy, Z. Kerényi, A. Takács, M. Papp, I. Petróczi, R. Gáborjányi, D. Silhavy, J. Pauk, and Z. Kertész

The reliable monitoring of field virus infections of crop species is important for both farmers and plant breeders. The aim of this study was to detect virus infections of winter wheat in the 2006/2007 season. Twelve well-known winter wheat varieties were sown on two different dates (11 th of October and 3 rd of November 2006). Leaves of two individuals from each genotype were collected on 23rd of April 2007 to detect the virus infections ( Barley stripe mosaic virus — BSMV, Barley yellow dwarf virus — BYDV-PAV, Wheat dwarf virus — WDV and Wheat streak mosaic virus — WSMV) after an extra mild autumn- and wintertime. Virus infections were detected by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). The aphid-transmitted BYDV-PAV was found frequently whereas other viruses were presented very rarely or were not detected. Forty-six per cent of the tested wheat plants proved to be infected by BYDV-PAV in ELISA, while using PCR, the virus infections with BYDV-PAV was found in 58% of the samples. Further, these results suggest that the optimal sowing time is critical in the control of cereal virus diseases, and additionally, that wheat varieties respond to the virus infections differently.

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