Proteomic analysis of stachyose contribution to the growth of Lactobacillus acidophilus CICC22162.

Stachyose is a functional oligosaccharide, acting as a potential prebiotic for colonic fermentation. To understand the mechanism of how stachyose promotes the growth of probiotic bacterium, we analyzed the differences of the proteome of Lactobacillus acidophilus grown on stachyose or glucose. By a combination of two-dimensional electrophoresis and mass spectrometry analysis, we observed 16 proteins differentially abundant under these two conditions and identified 9 protein spots. Six of these proteins were highly abundant when stachyose was used as the sole carbon source. They included the phosphotransferase system, the energy coupling factor (ECF) transporter and the mannose-6-phosphate isomerase, involved in the uptake and catabolism of stachyose in Lactobacillus acidophilus CICC22162. Supportively, these observations were validated by quantitative RT-PCR analysis and enzymatic activity determination. Positive correlation was found between the content of the proteins and their mRNA levels. Additionally, we explored the recognition mechanism for stachyose binding to the newly identified ECF transporter by MD simulations and free energy analysis. Taken together, these results provide new insights into the mechanism of stachyose in promoting the growth of probiotic bacterium.

Experimental free-space quantum key distribution with efficient error correction.

We report a 17-km free-space quantum key distribution (QKD) experiment using an engineering model of the space-bound optical transmitter and a ground station for satellite-ground QKD. The final key rate of ~ 0.5 kbps is achieved in this experiment with the quantum bit error rate (QBER) of ~ 3.4%. An efficient error correction algorithm, Turbo Code, is employed. Compared with the current error correction algorithm of Cascade, a high-efficiency error correction is realized by Turbo Code with only one-time data exchange. For a low QBER, with only one-time data exchange, the final key rates based on Turbo code are similar with Cascade. As the QBER increases, Turbo Code gives higher final key rates than Cascade. Our results experimentally demonstrate the feasibility of satellite-ground QKD and show that the efficient error correction based on Turbo Code is potentially useful for the satellite-ground quantum communication.

Proteomic analysis of ginsenoside Re attenuates hydrogen peroxide-induced oxidative stress in human umbilical vein endothelial cells.

Ginsenoside Re is an active component in ginseng that has attracted much attention because of its evident therapeutic effects on the cardiovascular system. However, little basic information is available on the mechanisms and pharmacological effects of ginsenoside Re. The potential mechanisms and protective effects of Re on H2O2-induced oxidative injury in human umbilical vein endothelial cells (HUVECs) were investigated in this study. An oxidative injury model was established using H2O2. The anti-oxidative effects of Re were determined using a series of experiments, such as MTT and anti-oxidative indicator assays. The potential protective mechanisms of Re were explored at the proteomic level, and differentially expressed proteins were validated by quantitative real-time polymerase chain reaction and western blotting. Results indicated that Re could be a potential anti-oxidant to protect HUVECs against oxidative stress damage. Proteomic analysis showed that the expression of 23 protein spots was upregulated in Re and H2O2 groups to resist oxidative stress, 15 of which were identified by their mass spectrum. These upregulated proteins were involved in stress response, anti-oxidative systems, protein synthesis, regulation of transcription and post-translational modifications, and repair of mitochondrial functions. This study may provide new insights into the mechanisms of ginsenoside Re in protecting the cardiovascular system.

Protective effect of rhein against oxidative stress-related endothelial cell injury.

Endothelial cell injury caused by reactive oxygen species (ROS) plays a critical role in the pathogenesis of atherosclerosis. Therefore, phytochemicals or antioxidants that inhibit the production of ROS have clinical value for the treatment of atherosclerosis. Rhein is one of the most important active components of rhubarb (Rheum officinale), a famous traditional Chinese remedy that possesses potent antioxidant properties through undefined mechanism(s). The aim of the present study was to determine whether rhein inhibits hydrogen peroxide (H2O2)-induced injury in human umbilical vein endothelial cells (HUVECs). The oxidative injury model was established with H2O2. HUVECs were treated with different concentrations of rhein in the presence/absence of H2O2. The protective effects of rhein against the injury caused by H2O2 were evaluated. HUVECs incubated with 200 µmol/l H2O2 had significantly decreased cell viability, which was accompanied by cell apoptosis and upregulated Bid and caspase-3, -8 and -9 mRNA expression. Meanwhile, H2O2 treatment induced a marked increase in malondialdehyde (MDA) and lactate dehydrogenase (LDH) content and decreased the nitric oxide (NO) content and nitrogen oxide synthase (NOS), superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activity. However, pre-treatment with different rhein concentrations (2, 4, 8 and 16 µmol/l) significantly increased the viability of H2O2-injured HUVECs, decreased the MDA and LDH content, increased the NO content and NOS, SOD and GSH-PX activity in a dose-dependent manner and resulted in significant recovery from H2O2-induced cell apoptosis. In addition, the results of the qRT-PCR indicated that pre­treatment with rhein downregulates the expression of Bid and caspase-3, -8 and -9 mRNA, which plays a key role in H2O2-induced cell apoptosis. The present study shows that rhein protects endothelial cells against oxidative injury induced by H2O2, suggesting that rhein is a potential compound for the prevention and treatment of atherosclerosis.

[Study on extraction of the total saponins of Chinese yam].

A method for the determination of total saponins of Chinese yam was established. The dioscin was used as a standard compound, the vanillin-perchloric acid as chromogenic agent and glacial acetic acid as solvent. The extraction technique of asponins from Chinese yam was studied by spectrometric method. Extracting temperature, extracting time, ethanol concentration and the ratio of raw material and water were selected as four factors to design the orthogonal test, and the optical condition of extraction was obtained. The results showed that the optical condition of extraction was as following: extracting temperature 60 degrees C, extracting time 6 h, ethanol concetration 80%, and the ratio of raw material and water 1:8.