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Shi W.-W.,Shanghai JiaoTong University | Shi W.-W.,Bor h Food Safety Research Center | Huang H.-Y.,Shanghai JiaoTong University | Wang N.,Key Laboratory of Urban Agriculture South | And 4 more authors.
Fresenius Environmental Bulletin | Year: 2013

A novel nitrate-uptake bacterial strain Bacillus megaterium NCT-2 was isolated from greenhouse soil. This isolate could utilize nitrate as sole source of nitrogen. The resting cells could remove nitrate over 200 mg/L within 48h. Although nitrate was not essential for the growth of this microorganism, it increased the growth rate. To characterize the microbial nitrate uptake, we measured the effect of sodium chloride and heavy metal ions on the uptake. The increase of sodium chloride concentration inhibited the nitrate removal. When sodium chloride concentration exceed 10%, only very little uptake was observed. And that inhibitory effect of sodium chloride on both nitrate uptake and bacterial growth was dose-dependent. The heavy metal ions, such as Ni 2+, Cd2+, and Cu2+, could inhibit the nitrate uptake. In the opposite case, Zn2+ and Mn2+ had no effects on the nitrate removal. Furthermore, Fe3+can significantly promote the uptake. The effects of metal ions on uptake were consistent with that on the growth of strain NCT-2. This study suggested the strain NCT-2 could be widely used for bioremediation of soil contaminated by nitrate. © by PSP. Source


Xing H.,Shanghai JiaoTong University | Xing H.,Key Laboratory of Urban Agriculture South | Zhan S.,Shanghai JiaoTong University | Zhan S.,Key Laboratory of Urban Agriculture South | And 7 more authors.
RSC Advances | Year: 2013

We report a rapid and facile colorimetric sensing method for melamine detection in milk using aptamer based nanoparticles (AuNPs). Aptamers can absorb on the surface of AuNPs and electrostatically interact with poly(diallyldimethylammonium chloride) (PDDA), which protects the AuNPs from aggregation. The introduction of melamine causes a melamine-aptamer complex to form via hydrogen bonding, thus the resulting cationic polymer can aggregate the AuNPs and cause a remarkable change in color. As a result of this, the presence of melamine can be determined by the naked eye and by measuring absorbance. This sensor is selective for the detection of melamine in milk samples and has a limit of detection of 34 nM. Since aptamer-modified AuNPs are more stable and selective than unmodified AuNPs in the sensing of melamine, we hope that this type of detection method will be helpful for the detection of other small molecules. © 2013 The Royal Society of Chemistry. Source


Zhong L.,Shanghai JiaoTong University | Zhong L.,Bor h Food Safety Research Center | Wang L.,Shanghai JiaoTong University | Wang L.,Bor h Food Safety Research Center | And 20 more authors.
BioMetals | Year: 2015

Copper (Cu) ion is essential for the biological systems, however, high level of CuCl2 exposure causes detrimental effects, which leads to cell apoptosis. Nitric oxide (NO) is an efficient cell signal messenger, which plays an important role in cell apoptosis. However, the potential mechanism of an early phase Cu-induced acute cytotoxicity through the nitric oxide synthase (NOS) signaling pathway and its interaction has not been studied. In this report, we provide data showing that high level of CuCl2 could rapidly decrease the NO production with the release of Ca2+ and Zn2+, and then modulate the transcriptional and translational expression of NOSs in MCF-7 cells. The reactive oxygen species (ROS) level in cells was increased after high level of CuCl2 exposure, which led to the alpha subunit of eukaryotic initiation factor 2 phosphorylation. By using the free radical scavenger N-acetyl-L-cysteine or the NOS substrate L-arginine, it demonstrated that NOS played a critical role on the Cu-induced ROS generation, which further led to the oxidative stress and cell apoptosis. These results suggested that Cu-induced apoptosis was associated with the oxidative stress, and through the NOS-mediated signaling pathway. © Springer Science+Business Media 2014. Source


Zhong L.,Shanghai JiaoTong University | Zhong L.,Bor h Food Safety Research Center | Wang L.,Shanghai JiaoTong University | Wang L.,Key Laboratory of Urban Agriculture South | And 20 more authors.
Biological Trace Element Research | Year: 2015

Literature to date has confirmed that cadmium (Cd) can accomplish its toxic effects via the free radical-induced damage, but Cd itself cannot generate free radicals directly. Nitric oxide (NO) is a fundamental molecule that interplays with reactive oxygen species (ROS), which may be associated with the Cd-induced cytotoxicity. However, the role of nitric oxide synthase (NOS) in an early phase Cd-induced acute cytotoxicity and its interaction has not been studied. In this report, we provide data showing that CdCl2 (10 μM, 100 μM, 1 mM) could modulate NOS activity in terms of NO production which was first suppressed with the release of Ca2+ and Zn2+, then induced with the transcriptional and translational activation of the three NOS isoforms in a possible feedback manner. The ROS level in cells was increased after CdCl2 exposure. By using the free radical scavenger N-acetyl-l-cysteine (LNAC) or the NOS activity inhibitor NG-methyl-l-arginine (LNMMA), it was demonstrated that NOS played a critical role on the Cd-induced ROS generation. The Cd-induced cytotoxicity was associated with the NOS-mediated oxidative stress in MCF-7 cells. © 2014, Springer Science+Business Media New York. Source


Luo Y.,Bor h Food Safety Research Center | He L.,Bor h Food Safety Research Center | He L.,Shanghai JiaoTong University | Zhan S.,Bor h Food Safety Research Center | And 7 more authors.
Journal of Agricultural and Food Chemistry | Year: 2014

This paper reports an ultrasensitive resonance scattering (RS) method to detect tetracycline (TET) in milk based on the competition of aptamers between nanogold and TET, aggregation of naked nanogold, nanocatalytic Fehling reaction, and RS signals of catalytic product Cu2O cubic. The detection principle was confirmed by the nanoparticle size analyzer (NANOS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The variations of RS intensity had good linear correlation with TET concentrations, and the limit of detection was calculated as 11.6 nM. The proposed method was successfully applied for analysis of TET in milk, with total recoveries ranging from 105 to 109%. © 2014 American Chemical Society. Source

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