凝溶蛋白对骨骼肌天然细肌丝的作用

凝溶蛋白是Ｆ－肌动蛋白丝的钙依赖性切割性蛋白质．经过焦磷酸溶液选择性抽提和微酸性介质的有效分离,可以得到纯度较高的天然细肌丝．在Ｃａ２＋存在时,凝溶蛋白可以切割天然细肌丝．但是,凝溶蛋白对天然细肌丝的作用时程与其对Ｆ－肌动蛋白丝的作用有着显著差异,提示细肌丝中的非肌动蛋白蛋白质可能影响了凝溶蛋白对天然细肌丝的结合或者切割速率．     

Specific immunological detection of the (V+C)(-) fibronectin isoform.

The population of fibronectins in adult mammalian cartilage includes high levels of a cartilage-specific (V+C)(-) isoform which lacks the V, III-15, and I-10 segments and thus contains a novel junction between protein segments III-14 and I-11. We report production of a monoclonal antibody specific for (V+C)(-) fibronectin without cross-recognition of V(+)C(+) and V(-)C(+) isoforms found in plasma and other tissues. Presentation of epitope to this antibody requires the III-14/I-11 junction, but the epitope itself extends beyond 14 amino acids immediately surrounding the junction site and involves a conformational change in III-14 and/or the N-terminal portion of I-11. The antibody, designated Mab 5D10 anti (V+C)(-), displays specificity for (V+C)(-) fibronectin from multiple mammalian species including humans and utility in immunoblots, immunohistochemistry, and ELISA.     

Thermodynamic and kinetic analysis of the interaction between hepatitis B surface antibody and antigen on a gold electrode modified with cysteamine and colloidal gold via electrochemistry

Hepatitis B surface antibody (HBsAb) was immobilized to the surface of a gold electrode modified with cysteamine and colloidal gold as matrices to detect hepatitis B surface antigen (HBsAg). Differential pulse voltammetry (DPV) method was used for the investigation of the specific interaction between the immobilized HBsAb and HBsAg in solution, which was followed as a change of peak current in DPV with time. With the modified gold electrode, the differences in affinity of HBsAb with HBsAg at the temperatures of 37 and 40 °C were easily distinguished and the kinetic rate constants (k_ass and k_diss) and kinetic affinity constant K were determined from the curves of current versus time. In addition, the thermodynamic constants, ΔG, ΔH and ΔS, of the interaction at 37 °C were calculated, which were −56.65, −64.54 and −25.45 kJ mol⁻¹, respectively.     

Molecular Characterization of the Total Bacteria and Dissimilatory Arsenate-Reducing Bacteria in Core Sediments of the Jianghan Plain,Central China

Arsenic contamination in groundwater has been reported in the Jianghan Plain of China since 2005, yet little is known about the microbial communities involved in As mobilization in this area, especially the dissimilatory arsenate-reducing bacteria (DARB) communities. Here, we conducted a cultivation-independent investigation on core sediments collected from a region with arsenic-contaminated groundwater in the Jianghan Plain to reveal the total bacteria and DARB community structures. Highly diverse As-resistant bacteria communities were found from sediment samples via high-throughput sequencing of 16S rRNA genes. Notably, we identified 27 unique arrA gene (encoding the alpha subunit of dissimilatory arsenate reductase) phylotypes, none of which was related to any previously described arrA gene sequence. This suggests a novel and unique DARB community in the sediments of the Jianghan Plain and expands our knowledge about the distribution and diversity of this group of bacteria in natural environments. Moreover, RDA and CCA demonstrated that total bacterial communities and specific functional groups are controlled by different environmental factors. Specifically, sediment pH, NH₄⁺, total nitrogen, total Fe, total organic carbon and total phosphorus were the key factors driving total bacterial community compositions, while As significantly shaped DARB community structures. This report is the first to describe DARB communities and their correlation with environmental factors in Jianghan Plain sediments, which could give us clues about the origin of the arsenic contamination of groundwater in this region.     

Exosomes from human-bone-marrow-derived mesenchymal stem cells protect against renal ischemia/reperfusion injury via transferring miR-199a-3p

Renal ischemia/reperfusion (I/R) injury is the main reason for acute kidney injury (AKI) and is closely related to high morbidity and mortality. In this study, we found that exosomes from human-bone-marrow-derived mesenchymal stem cells (hBMSC-Exos) play a protective role in hypoxia/reoxygenation (H/R) injury. hBMSC-Exos were enriched in miR-199a-3p, and hBMSC-Exo treatment increased the expression level of miR-199a-3p in renal cells. We further explored the function of miR-199a-3p on H/R injury. miR-199a-3p was knocked down in hBMSCs with a miR-199a-3p inhibitor. HK-2 cells cocultured with miR-199a-3p-knockdown hBMSCs were more susceptible to H/R injury and showed more apoptosis than those cocultured with hBMSCs or miR-199a-3p-overexpressing hBMSCs. Meanwhile, we found that HK-2 cells exposed to H/R treatment incubated with hBMSC-Exos decreased semaphorin 3A (Sema3A) and activated the protein kinase B (AKT) and extracellular-signal-regulated kinase (ERK) pathways. However, HK-2 cells cocultured with miR-199a-3p-knockdown hBMSCs restored Sema3A expression and blocked the activation of the AKT and ERK pathways. Moreover, knocking down Sema3A could reactivate the AKT and ERK pathways suppressed by a miR-199a-3p inhibitor. In vivo, we injected hBMSC-Exos into mice suffering from I/R injury; this treatment induced functional recovery and histologic protection and reduced cleaved caspase-3 and Sema3A expression levels, as shown by immunohistochemistry. On the whole, this study demonstrated an antiapoptotic effect of hBMSC-Exos, which protected against I/R injury, via delivering miR-199a-3p to renal cells, downregulating Sema3A expression and thereby activating the AKT and ERK pathways. These findings reveal a novel mechanism of AKI treated with hBMSC-Exos and provide a therapeutic method for kidney diseases.     

Electrochemical recognition for sugars on the chitosan-poly(diallyldimethylammonium chloride)-nano-Prussian blue/nano-Au/4-mercaptophenylboronic acid modified glassy carbon electrode

A new amperometric biosensor for the detection of sugars was prepared. A glassy carbon electrode was modified with Prussian blue (PB) nanoparticles protected by chitosan (CS) and poly(diallyldimethylammonium chloride) (PDDA), and then gold nanoparticles were assembled onto the electrode followed by the assembly of 4-mercaptophenylboronic acid (MPBA) onto the surface of gold nanoparticles through a sulfur–Au bond to fabricate a self-assembled biosensor. The PB nanoparticles protected by CS and PDDA were characterized using transmission electron microscopy and UV–vis absorption spectroscopy. The characterization of the self-assembled electrode was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The pK _a values of the MPBA monolayer before and after combining with sugars were determined. The fabricated electrode exhibited excellent performances for determining d(+)-glucose, d(+)-mannose, and d(−)-fructose on the basis of the change in i _p of the Fe(CN)₆^3−/4− ion in the presence of sugars.