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Zhang J.,Hubei University of Education | Li R.,Wuhan University | Li R.,China Tobacco Hubei Industrial LLC | Jiang F.-L.,Wuhan University | And 11 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2014

In this work, we proposed an immobilization scheme targeting Escherichia coli bacterial cells onto gold surface utilizing polypeptide RGD's binding specificity to gold particles. Adsorption kinetics of extracellular Herring Sperm DNA on E. coli was then studied using electrochemical methods along with surface plasmon resonance spectroscopy through this immobilization scheme. The adsorption equilibrium constants of DNA adsorbing to E. coli from electrochemical method and surface plasmon resonance spectroscopy, were (5.596±0.462)×105Lmol-1 and (1.24±0.361)×105Lmol-1, accordingly. Importantly, this is the first study that used an electrochemical method to express the adsorptive action of DNA by E. coli. © 2014 Elsevier B.V.

Xu Z.,Henan Agricultural University | Shao H.,Henan Agricultural University | Sun S.,China Tobacco Hubei Industrial Corporation | Zheng C.,Henan Agricultural University | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Selenium is an essential trace element for humans. It plays important roles in eliminating peroxide, thereby protecting cells from damage and delaying aging. Se also has significant effects on crop growth and quality; appropriate amounts of Se can enhance resistance, increase crop yields, and improve many quality attributes of crops. When supplied at the right concentrations, Se not only increases the growth and quality of flue-cured tobacco (Nicotiana tobacum), but also decreases the amount and toxicity of harmful substances in tobacco smoke, especially tar. Therefore, Se-rich tobacco may alleviate the harmful effects of smoking on the body by suppressing tumors. The aim of these experiments was to produce Se rich tobacco leaves, which have the potential to improve the safety of tobacco raw materials. We tested the effects of Se on flue-cured tobacco (variety K326) grown in pots. Se was added to soil at seven different concentrations; 0, 2, 5, 8, 12, 16, and 24 mg Se/kg soil. We evaluated the physiological properties, Se content, and Se accumulation rate of tobacco during the growing stage. The results showed that increasing concentrations of Se in the soil were associated with greater growth inhibition or even death of tobacco plants. At concentrations of Se less than 8 mg/kg soil, the survival rates of tobacco were 100%. In contrast, at Se concentrations of 12, 16, and 24 mg/kg soil, the survival rate of tobacco plants was 81.25, 75, and 56. 25%, respectively. At low concentrations (< 12 mg Se/kg soil), Se promoted tobacco growth and resulted in greater accumulation of above and below-ground dry matter, compared with those of the control (P<0. 05). At higher concentrations (>16 mg Se/kg soil), Se resulted in decreased dry matter compared with the control (P < 0. 05). These results demonstrated that Se satisfies the Bertrand biological dose law, in that low concentrations promoted plant growth while high concentrations had an inhibitory effect. Low concentrations of Se (≤8 mg Se/kg soil) were associated with increased concentrations of chlorophyll a, chlorophyll b, chlorophyll a + b, and carotenoids in flue-cured tobacco leaves, and increased activities of superoxide dismutase (SOD) and peroxidase (POD). Higher concentrations of Se (≥12 mg Se/kg soil) decreased SOD and POD activities, which could lead to inhibition of tobacco growth or even plant death. In an appropriate range of Se concentrations, the concentration of malondialdehyde (MDA; a breakdown product of lipid peroxidation) decreased with increasing soil concentrations of Se, indicating that Se alleviated membrane peroxidation. In addition, POD activity increased and SOD activity decreased during the growth period, and the MDA content was lower in the middle growth stage than in the earlier and later growth stages. The Se content in flue-cured tobacco leaves increased with increasing concentrations of Se in the soil. The rate of Se accumulation increased at the early growth stage and then decreased. The maximum Se accumulation rate was observed at a concentration range of 5-12 mg Se/kg soil. Moreover, there were strong correlations between Se content in flue-cured tobacco and most other physical indexes.

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