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Effects of some dietary o -dihydroxyphenols on biochemical markers of oxidative stress within tissues of Sitobion avenae (Fabricius), (Homoptera, Aphididae) and Rhopalosiphum padi (Linnaeus), (Homoptera, Aphididae) has been studied. Among the studied aphid morphs the highest concentration of total thiols, hydrogen peroxide and lipid peroxidation products (TBARS) was noted for winged adults (alatae). Higher content of H 2 O 2 was observed within tissues of the oligophagous species R. padi while the monophagous species S. avenae had higher TBARS and total thiols concentration. Aphids exposed the dietary pro-oxidative o -dihydroxyphenols (quercetin, caffeic acid, chlorogenic acid) demonstrated significantly lower concentration of total sulfhydryls and higher level of TBARS and H 2 O 2 than the control ones. Among the studied compounds, chlorogenic acid showed the strongest effect on the level of thiols and TBARS while caffeic acid caused the highest accumulation of the hydrogen peroxide within the aphid tissues.

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Acta Biologica Hungarica
Authors: Márta Kotormán, Zita Kelemen, Phanindra Babu Kasi, and János Nemcsók

We tested the amyloid fibril formation inhibitory effect of seven teas diluted in 55% ethanol at pH 7.0 at a protein concentration of 0.15 mg/ml α-chymotrypsin. In the experiments we investigated the formation and inhibition of amyloid fibrils by turbidity measurements, aggregation kinetics experiments and Congo red binding assay. The results suggest that the different teas effectively inhibit the formation of amyloidlike fibrils. The two most potent inhibitors were peppermint and melilot, extracts which almost completely inhibited the formation of aggregates in 5-fold dilution. The inhibitory effect on the aggregation formation of melilot and peppermint extracts was concentration dependant. The extent of inhibition was found to be proportional with the total concentration of phenolic compounds.

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The effect of benomyl as a fungicide on growth rate and ultrastructure of two isolates (P623 and P1319) of Phytophthora infestants is compared. Using different concentrations (50, 100, 200 and 500 ppm) of benomyl caused an inhibition of the mycelial growth of both isolates depending on the degree of concentration. The isolate P1319 was found to be more sensitive to benomyl than the isolate P623. Ultrastructural studies confirmedthese observations. The hyphae of isolate P1319 subjected to 100 and 500 ppm benomyl showed severe changes in the cítoplasm more than isolate P623. The increase of lipid bodies and vacuoles in hyphal cytoplasm of both isolates was the characteristic phenomenon after treatment of benomylparticulary at the concentration of 500 ppm.

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The objective of the present study was to evaluate possible genetic changes in cultured human lymphocytes treated with estradiol, using the cytokinesis block micronucleus assay. Eight experimental concentrations of estradiol were used (range from 7×10-10 M to 0.7×10-4 M). The obtained results indicate that estradiol exhibits aneugenic and/or clastogenic effects, expressed as increased frequency of micronucleated lymphocytes at two highest experimental concentrations used in this investigation. In addition to genotoxic effects, these concentrations decreased the cytokinesis block proliferation index (CBPI) and percentage of binucleated cells, indicating the cell cycle delay and possible cytotoxic effects. In conclusion, estradiol treatment might represent a human health risk, especially if overdosed or used for a prolonged period of time.

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The effects of aluminium on seed germination, shoot, root and dry weight of two wheat cultivars were studied. The seed germination of Triticum aestivum cv. 'Faisalabad 85' and Triticum aestivum cv. 'Blue Silver' was significantly (p < 0.05) affected by different concentration of aluminium as compared to the control. The increase in concentration of aluminium at 10 ppm suppressed the root and shoot length in T. aestivum cv. 'Faisalabad 85', whereas the reduction in shoot length was observed for T. aestivum cv. 'Blue Silver' at 15 ppm. A significant (p < 0.05) reduction in dry weight of 'Blue Silver' was observed at 25 ppm aluminium.

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The possibility of plant regeneration via direct somatic embryogenesis from leaf tissue of Drosera spathulata Labill. has been studied, using MS medium supplemented with various concentration of NAA and BAP. Scanning electron microscopy investigations in combination with histological analysis verified direct somatic embryogenesis by formation of globular, torpedo-shaped, heart-shaped and cotyledonary embryo like structures. Optimal somatic embryo formation occurred when leaves were pre-treated with low concentration (0.005 mg l-1) of 2,4-D within 6 h. Prolonged influence of 2,4-D to 24-48 h led to the expression of morphological and developmental abnormalities.

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Plants have evolved complex mechanisms to perceive environmental cues and develop appropriate and coordinated responses to abiotic and biotic stresses. Considerable progress has been made towards a better understanding of the molecular mechanisms of plant response to a single stress. However, the existence of cross-tolerance to different stressors has proved to have great relevance in the control and regulation of organismal adaptation. In this study, we showed that cold pre-treatment (at 15, 10, 5 and 0 °C) enhanced chilling stress in two cultivars of tomato plants (Lycopersicon esculentum cv. ‘Tres Cantos’ and ‘Roma’), as indicated by de novo synthesis of stress proteins in the cold-treated plants than the control ones. The cold-treated ‘Roma’ seedlings were more resistant to chilling stress than ‘Cantos’. Active synthesis of 43 kDa heat shock proteins and some low molecular weight proteins took place after chilling stress in both cultivars. Seeds pre-treatment with systemin at three concentrations (10−6, 10−2 and 100 μM) or spraying the seedlings of two plants with the same concentrations leads to stressful polypeptides were detected as 16 kDa which is one from low molecular weight proteins were referred as vegetative storage proteins (VSPs). In ‘Tres Cantos’, the spraying of plants was more effective than the pre-soaking, while in ‘Roma’, the pre-soaking with systemin is more effective at low and moderate concentrations (10−6 and 10−2 μM), meanwhile, the spraying with systemin is more effective at high concentration (100 μM).

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A simple to calculate and statistically testable method is proposed for assessing species abundance unevenness or dominance concentration within plant communities. Dominance rather than evenness is considered the preferred measure, because perfect evenness can be defined and used as a benchmark for comparing communities regardless of floristic richness. Four dominance (Simpson, Berger-Parker, McIntosh, and a proposed [DW]) and four evenness (Carmargo, Gini, Shannon, and Williams) indices are comparatively analyzed. The Simpson, McIntosh, Gini, and Williams indices were correlated with species richness, the Berger-Parker index was correlated with total species cover, the Shannon index over-estimated evenness, the Simpson index under-estimated dominance concentration, and a nonlinear relationship occurred between the Simpson and all of the evenness indices. Only DW and the Carmargo indices fulfilled the technical requirements established for evenness with appropriate reversals of criteria for assessing a dominance concentration index. Determination of DW was based on the maximum difference between cumulative proportion (also referred to as Lorenz curve or partial order) and perfect evenness values. The conventional assumption that dominance (D) is the complete opposite of evenness (E), as assessed by indices, was found in practice to be lacking, without the inclusion of an error term (i.e., 1 = E + D + error). Therefore, both dominance concentration and evenness should be reported when characterizing plant communities.

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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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Acta Biologica Hungarica
Authors: Ozlem Temiz-Arpaci, Fatma Doğanc, Duygu Sac, Elmas Sari, Fatma Kaynak-Onurdag, and Suzan Okten

A series of 2-(p-substituted phenyl)-5-[(4-substituted phenyl) sulfonylamido]-benzoxazoles were synthesized and tested for their antimicrobial activities. The structures of the new derivatives were elucidated by spectral techniques. The minimum inhibitory concentrations (MIC) of the new benzoxazoles were determined against standard bacterial and fungal strains and drug-resistant isolates and compared to those of several reference drugs.

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