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Food Chem ; 337: 127761, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32777565


Amino and thiolated aptamers are the main aptamers used to construct label-free electrochemical impedimetric aptasensors. In this study, the modification performance and electrochemical properties of amino aptamers and thiolated aptamers were studied in the construction of label-free impedimetric sensors. The results showed that the initial modification density of amino aptamers was higher than that of thiol aptamers. Aptamers can recognize and bind OTA to generate electrical signals. The higher the density of aptamer modification was, the better the electric signals were. If only considering the initial modification density, amino aptamers were more suitable for the preparation of aptasensors than thiolated aptamers. However, the modification density of the amino aptamer decreased with the prolonged immersion time in 1 mM HCl solution, which suggests that the stability of this sensor was poor. However, the thiolated aptamer maintained relatively constant density and could be reused. Thus, the thiolated aptasensor had a wide range and good reproducibility and stability for the determination of ochratoxin A (OTA). In addition, this study proved that gold nanoparticles play an important role in signal amplification by increasing the effective gold surface to fix more aptamers in the process of sensor preparation.

Can J Microbiol ; 62(2): 161-72, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26751338


Trichothecium roseum is one of the most important postharvest pathogens in arid and semiarid regions. Sodium silicate (NaSi) and environmental pH have significant inhibitory effects on fungal growth. However, no study has addressed the relationship of NaSi and pH in combination and the effects on T. roseum. In this work, we showed that spore germination, germ tube elongation, and mycelial growth of T. roseum were significantly inhibited by various NaSi concentrations, which had corresponding increasing pHs. Furthermore, these NaSi solutions showed a much greater impact than did pH treatments alone. The pathogenicity of NaSi-treated conidia on a model assay (conidia-inoculated apple fruit) was dramatically reduced, whereas no changes of pathogenicity were evident for the corresponding pH (various sodium hydroxide (NaOH) solutions) treatments. Fluorescent microscopy, using propidium iodide staining, showed damage of the plasma membranes of T. roseum conidia treated with both NaSi and NaOH, although the damage was more severe with NaSi. Leakage of proteins and sugars was significantly higher in NaSi-treated and NaOH-treated conidia than in untreated controls. In addition, serious damage was observed in the conidia exposed to NaSi for longer periods of time. Ultrastructural observations showed that treatment with either NaSi or NaOH caused a plasmolysis state and disorganized organelles. Taken together the results show that NaSi has inhibitory effects on T. roseum and that the inherent higher pH of NaSi solutions of higher concentrations simply acts as an enhancer of the inhibitory effects of NaSi.

Fungos Mitospóricos/efeitos dos fármacos , Silicatos/farmacologia , Frutas/microbiologia , Proteínas Fúngicas/análise , Concentração de Íons de Hidrogênio , Malus/microbiologia , Fungos Mitospóricos/crescimento & desenvolvimento , Hidróxido de Sódio/farmacologia , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/ultraestrutura
Food Chem ; 151: 236-42, 2014 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-24423527


Four trichothecenes (Fus-X, 3ADON, DAS and T-2) were detected in potato tubers inoculated with Fusarium spp. by UPLC-MS/MS. The influence of cultivars, Fusarium strains and storage temperature on trichothecenes production was evaluated. The concentration of trichothecenecs was much higher in susceptible cultivar (Longshu No. 3) than in resistant one (Longshu No. 6). The susceptible cultivar infected with Fusarium sulphureum had the maximum concentration of Fus-X, 3ADON and DAS. Among the three Fusarium strains, Fusarium solani had the strongest ability to produce T-2 in both susceptible and resistant cultivars. Room temperature storage was more likely to accumulate trichothecenes than low temperature storage. Meanwhile, the trichothecenes were found not only in the lesion but also in the adjacent asymptomatic tissue. Trichothecenes concentration showed a strong trend of decline with increase in distance from the infection point.

Fusarium/química , Solanum tuberosum/química , Espectrometria de Massas em Tandem/métodos , Tricotecenos/análise , Micotoxinas , Tubérculos/química , Temperatura