Mapping Post-translational Modifications of Histones H2A, H2B and H4 in Schizosaccharomyces pombe

Core histones are known to carry a variety of post-translational modifications (PTMs), including acetylation, phosphorylation, methylation and ubiquitination, which play important roles in the epigenetic control of gene expression. The nature and biological functions of these PTMs in histones from plants, animals and budding yeast have been extensively investigated. In contrast, the corresponding studies for fission yeast were mainly focused on histone H3. In the present study, we applied LC-nano-ESI-MS/MS, coupled with multiple protease digestion, to identify PTMs in histones H2A, H2B and H4 from Schizosaccharomyces pombe (S. pombe), the typical model organism of fission yeast. Various protease digestions provided high sequence coverage for PTM mapping, and accurate mass measurement of fragment ions allowed for unambiguous differentiation of acetylation from tri-methylation. Many modification sites conserved in other organisms were identified in S. pombe. In addition, some unique modification sites, including N-terminal acetylation in H2A and H2B as well as K123 acetylation in H2A.β, were observed. Our results provide a comprehensive picture of the PTMs of histones H2A, H2B and H4 in S. pombe, which serves as a foundation for future investigations on the regulation and functions of histone modifications in this important model organism.     

锌-丙酸铵还原体系用于氢化偶氮苯的合成

选用锌粉和镁粉与不同饱和铵盐（草酸铵、丙酸铵和苯甲酸铵）水溶液组成还原体系,由偶氮苯制备氢化偶氮苯,根据反应时间及结果选取锌一饱和丙酸铵水溶液为最佳还原体系。在反应温度25℃时,研究了锌一饱和丙酸铵水溶液还原体系还原偶氮苯反应,考察了偶氮苯与锌粉物质的量比、饱和丙酸铵水溶液的用量对氢化偶氮苯收率的影响。实验结果表明：偶...     

Qualitative and quantitative determination of polyacetylenes in different Bupleurum species by high performance liquid chromatography with diode array detector and mass spectrometry

Polyacetylenes are main toxic ingredients in Bupleurum longiradiatum, a poisonous plant that has ever been misused as substitutes for Chaihu (Bupleuri Radix). For the first time, a high-performance liquid chromatography method coupled with diode array detector and mass spectrometry (HPLC-DAD-MS) was developed for qualitative and quantitative analysis of nine polyacetylenes in Bupleurum species. All references, including two new polyacetylenes, were isolated from B. longiradiatum and purified using a semi-preparation HPLC chromatography. The analysis was performed on a TSKgel ODS-100V C18 column (3 μm, 150 mm x 4.6 mm i.d.) using a gradient system of acetonitrile and water, with diode array detection (254 nm). The method was validated for linearity, precision, accuracy, limit of detection and quantification. A total of 27 Bupleurum samples were examined with this method, which showed a great variety in the distribution and contents of the polyacetylenes. It was found that polyacetylenes (1-8) were the main ingredients in B. longiradiatum, while a few kinds of polyacetylenes (5-8) were also identified in B. smithii, B. smithii var. parvifolium, B. bicaule and B. angustissimum. However, no polyacetylenes (1-9) were detected in the authentic Chaihu samples and the other Bupleurum species. The results indicated that the toxic B. longiradiatum could readily be distinguished from other medicinal Bupleurum species based on the polyacetylene profiles, and the guidelines and quality control of polyacetylenes for Chaihu are useful. The acute toxicity of the ethanol extract of B. longiradiatum and its fractions was also investigated.     

Preparation of Ag nanoparticle-decorated poly(m-phenylenediamine) microparticles and their application for hydrogen peroxide detection

The chemical oxidation polymerization of m-phenylenediamine (MPD) by ammonium persulfate (APS) at room temperature results in the formation of poly(m-phenylenediamine) (PMPD) microparticles. The subsequent treatment of such microparticles with an aqueous AgNO(3) solution produces Ag nanoparticle (AgNP)-decorated PMPD microparticles. It was found that as-formed AgNPs exhibited remarkable catalytic performance toward the reduction of hydrogen peroxide (H(2)O(2)). The enzymeless H(2)O(2) sensor constructed with such composites showed a fast amperometric response time of less than 5 s, and the corresponding linear range and detection limit were estimated to be from 0.1 to 30 mM and 4.7 μM, respectively, at a signal-to-noise ratio of 3.     

Glucose Biosensor Using Glucose Oxidase and Electrospun Mn2O3‐Ag Nanofibers

The highly porous Mn₂O₃‐Ag nanofibers were fabricated by a facile two‐step procedure (electrospinning and calcination). The structure and composition of the Mn₂O₃‐Ag nanofibers were characterized by SEM, TEM, XRD, EDX and SAED. The as‐prepared Mn₂O₃‐Ag nanofibers were then employed as the immobilization matrix for glucose oxidase (GOD) to construct an amperometric glucose biosensor. The biosensor shows fast response to glucose, high sensitivity (40.60 µA mM^?1 cm^?2), low detection limit (1.73 µM at S/N=3), low K_m,app value and excellent selectivity. These results indicate that the novel Mn₂O₃‐Ag nanfibers‐GOD composite has great potential application in oxygen‐reduction based glucose biosensing.     

Extraction and isolation of lithospermic acid B from Salvia miltiorrhiza Bunge using aqueous two‐phase extraction followed by high‐performance liquid chromatography

A rapid and effective method integrating separation and purification of lithospermic acid B from Salvia miltiorrhiza Bunge was developed by combining an aqueous two‐phase system extraction with preparative chromatography. An aqueous two‐phase system of n‐butyl alcohol/KH₂PO₄ was chosen from seven systems. The influence of parameters including concentration of KH₂PO₄, n‐butyl alcohol concentration, pH, and the ratio of an aqueous two‐phase system to crude extract were investigated using a single factor design. Response surface methodology was subsequently used to find the optimal compositions of an aqueous two‐phase system. Keeping a solvent‐to‐solid ratio of 10, the final optimized composition of an aqueous two‐phase system was 39.1% w/w n‐butyl alcohol and 22.6% w/w KH₂PO₄. Under these conditions a recovery yield of 99.8% and a high partition coefficient of 310.4 were obtained. In a pilot‐scale experiment using optimized conditions, 18.79 g of lithospermic acid B with a purity of 70.5% and in a yield of 99.8% was separated from 0.5 kg of crude extract. Subsequently, 9.94 g lithospermic acid B with a purity of 99.3% and recovery yield of 70.3% was obtained with a preparative chromatographic process, and the two‐step total recovery was 70.1%.     

Enrichment and purification of deoxyschizandrin and γ-schizandrin from the extract of Schisandra chinensis fruit by macroporous resins

In present study, the performance and separation characteristics of 21 macroporous resins for the enrichment and purification of deoxyschizandrin and γ-schizandrin, the two major lignans from Schisandra chinensis extracts, were evaluated. According to our results, HPD5000, which adsorbs by the molecular tiers model, was the best macroporous resin, offering higher adsorption and desorption capacities and higher adsorption speed for deoxyschizandrin and γ-schizandrin than other resins. Columns packed with HPD5000 resin were used to perform dynamic adsorption and desorption tests to optimize the technical parameters of the separation process. The results showed that the best adsorption time is 4 h, the rate of adsorption is 0.85 mL/min (4 BV/h) and the rate of desorption is 0.43 mL/min (2 BV/h). After elution with 90% ethanol, the purity of deoxy-schizandrin increased 12.62-fold from 0.37% to 4.67%, the purity of γ-schizandrin increased 15.8-fold from 0.65% to 10.27%, and the recovery rate was more than 80%.     

A versatile platform for highly sensitive detection of protein: DNA enriching magnetic nanoparticles based rolling circle amplification immunoassay

A novel rolling circle amplification (RCA) immunoassay based on DNA enriching magnetic nanoparticles and assembled fluorescent DNA nanotags, magnetic nanoparticles-RCA immunoassay, is developed as a versatile fluorescence assay platform for highly sensitive proteins detection.     

Construction of biomimetic smart nanochannels with polymer membranes and application in energy conversion systems

Learning from nature has inspired the creation of intelligent devices to meet the increasing needs of the advanced community and also to better understand how to imitate biology. As one of biomimetic nanodevices, nanochannels or nanopores aroused particular interest because of their potential applications in nanofluidic devices, biosensing, filtration, and energy conversions. In this review we have summarized some recent results mainly focused on the design, construction and application in energy conversion systems. Like biological nanochannels, the prepared smart artificial nanochannels fabricated by ion track-etched polymer membranes and smart molecules show a great potential in the field of bioengineering and biotechnology. And these applications can not only help people to know and understand the living processes in nature, but can also inspire scientists to study and develop novel nanodevices with better performance for the mankind.