Essential (Mg,Fe, Zn and Cu) and Non-Essential (Cd and Pb) Elements in Predatory Insects (Vespa crabro and Vespa velutina): A Molecular Perspective

The recent introduction of the Asian yellow-legged hornet, Vespa velutina, into Europe has raised concern regarding the threat to honeybees and the competition with the European hornet, Vespa crabro. The aim of this study was to investigated essential (Mg, Fe, Zn, Cu) and non-essential (Cd and Pb) elements in these two species. Element concentrations were determined in the whole body and separately in the head, thorax and abdomen using atomic absorption spectrometry (AAS). The changes in essential element concentration and speciation during metamorphosis were also studied using size exclusion chromatography followed by AAS and proteomic analysis. In both species, the essential elements were more concentrated in the abdomen due to the presence of fat bodies. Magnesium, Fe and Zn concentrations were significantly higher in V. crabro than in V. velutina and could have been related to the higher aerobic energy demand of the former species required to sustain foraging flight. Low concentrations of Cd and Pb were indicative of low environmental exposure. The concentration and speciation of essential elements, particularly Fe, varied among the developmental stages, indicating a modification of ligand preferences during metamorphosis. Overall, the results in the present study provide a better understanding of the hornet metal metabolism and a foundation for additional studies.     

Towards Diastereomeric Pure Salts with Antisolvent Methods

Chiral molecules, especially enantiomers and diastereomers of purity > 99 %, present a significant market share within the chemical, pharmaceutical, and flavor industries. Antisolvent precipitations, both batch and semicontinuous operations to serve the current trends in flow chemistry were demonstrated to be environmentally benign and efficient tools in achieving high optical purities. Although salts are known to be insoluble in supercritical CO₂, instabilities of the nascent salts were detected and applied for increasing efficiency. Diastereomeric excess values of the crystalline products exceeded 99 % in maximum of three consecutive steps both by repeated resolution with half molar equivalent of the amine to the acid and by direct recrystallization of the salts.     

Monitoring Proteolysis During Cheddar Cheese Ripening Using Two-Dimensional Gel Electrophoresis

A 2-D gel electrophoretic method, consisting of isoelectric focusing and alkaline urea-PAGE was used to monitor proteolysis during ripening (180d, 5°C and 8°C) of full- and reduced-fat Cheddar cheese. The method enabled quantifying changes in levels of peptides in cheese with good spot-resolution. Results can complement those from other analyses, especially those for determining low MW peptides. Notable effects were found for cheese composition and ripening temperature on gel pattern and on relative levels of selected proteolysis products. In both cheese varieties, most peptides reached a maximum during the first 3 ripening months and gradually disappeared as ripening advanced.     

Electrophoretic Identification of Muscle Proteins in 7 Puffer Species

ABSTRACT: Species identification of puffer species using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with Coomassie blue and Coomassie blue/silver double staining was performed. A comparison was also made among extracts of sarcoplasmic, myofibrillar, SDS-soluble, and urea-soluble proteins. Protein bands of lower molecular weight showed the species-specific characteristics. Double staining better discriminated the protein banding patterns of different puffer species than Coomassie blue staining. Species identification of all tested puffers could be achieved by judging from the SDS-PAGE patterns of the 4 protein extracts stained with both stains along with protein band densities.     

Assignment of most genes encoding major peroxisomal polypeptides to chromosomal band V of the asporogenic yeast Candida tropicalis

The peroxisomes of the asporogenic yeast Candida tropicalis contain about 20 major polypeptides (PXPs). We have isolated a number of genes encoding them; 11 POX genes encoded independent PXPs and three POY genes were likely to encode three other PXPs. To locate these genes on the chromosomes, chromosomes of C. tropicalis were separated by pulsed-field gel electrophoresis. Eight chromosomal bands were observed over the range of 1.0 Mbp (band 1) to 2.8 Mbp (band VIII); the genome size was estimated to be about 20 Mbp. Southern blot analysis showed that ten genes were on band V, three genes were on band IV, and the other gene was on band VI. Three genes gave hybridization signals of nearly equal intensity on two different chromosomal bands: POX6A and POX8B, on bands V and VII; and POX8A, on bands IV and VI. Ribosomal RNA genes also hybridized to two bands, VI and VII. Most genes assigned to only one band hybridized to two restriction fragments produced by either NotI or SfiI endonuclease. The results suggested that C. tropicalis was diploid and that restriction sites were conserved little between homologues. The three POX genes that were found on two chromosomal bands hybridized to not more than two restriction fragments, implying that the allelic genes were present on different chromosomal bands.     

The effect of cooking on proteins from acha (Digitaria exilis) and durum wheat

The effect of cooking on proteins from acha and durum wheat was assessed from an analysis of protein extractability, gel electrophoretic profiles, in-vitro protein digestibility (IVPD) and the amino acid compositions of wholemeal flour and residue proteins. Heating wholemeal flour samples at 100–140°C (t = 10–40 min) resulted in 0–30% and 45–55% decreases in acha and durum protein solubility, respectively. In general, high molecular weight (30–70 k Da) protein subunits were more susceptible to heat damage. For both cereals, sodium dodecyl sulphate (SDS; 10 g litre^?1) and/or dithiothrcitol (DTT; 10 mM ) increased protein solubility in unheated and heated samples. The IVPD index was 90–91% and was not significantly altered by cooking (100–120°C, t = 40 min). Cooking at extreme temperatures (140°C, t = 40 min) reduced the IVPD by 8% (P = 0.05). Osborne fractionation resulted in a durum or acha residue level of 7.8% or 55.2%. Treatment with solvent containing propanol, SDS and/or DTT at room temperature followed by SDS-polyacrylamide gel electrophoresis of non-solubilised proteins showed that the glutelin fraction of acha, with the exception of a 65 kDa subunit, was insoluble owing to strong inter-subunit hydrophobic and disulphide interactions. Wholemeal acha flour and residue protein showed a significantly greater level of hydrophobic and sulphur amino acids as well as glutamine which is associated with H-bonding. The possibility that cereal protein solubility is also dependent on protein-carbohydrate links is discussed.     

微通道电泳芯片系统中信号识别算法的设计与实现

介绍适用于微通道电泳芯片系统的DNA测序软件的总体流程，以及其中的信号处理与识别算法。以激光诱导荧光检测系统所采集到的原始数据为源信号，以小波平滑和小波去噪为理论基础，将滤波算法和峰值识别算法综合在一起进行设计，从而使其适用于检测速度更快、样品量更少的微通道电泳芯片系统。将本算法应用于DNA片段的分离实验中，可以有效地达到滤波以及信号识别的目的。     

Enantioseparation of catechin and epicatechin in plant food by chiral capillary electrophoresis

The enantiomers of catechin and epicatechin were separated by chiral capillary electrophoresis using modified cyclodextrins as chiral selectors. Various conditions for the separation system were optimized, including the pH value and the concentration of the running buffer. A baseline separation of the catechin and epicatechin enantiomers could be achieved by using 0.1 mol l⁻¹ borate buffer (pH 8.5) with 12 mmol l⁻¹ (2-hydroxypropyl)-γ-cyclodextrin as chiral selector, a fused-silica capillary with 40 cm effective length (75 μm I.D.), +18 kV applied voltage, a temperature of 20 °C and direct UV detection at 280 nm. The method was applied to different plant food samples. (+)-Catechin and (−)-epicatechin could be verified as the most common flavan-3-ols. In the case of guaraná, however, we were able to identify all four enantiomers, both (+)- and (−)-catechin and (+)- and (−)-epicatechin, as naturally occurring compounds. This finding was verified by further isolation and purification of the flavan-3-ols and subsequent LC–MS analysis. This method allows for the identification of the authenticity of guaraná through the analysis of the catechin and epicatechin enantiomers, additionally to the conventional methods like HPLC.     

浓缩~(235)U诱发免疫细胞凋亡的电镜和琼脂糖凝胶电泳研究

研究了浓缩235U内照射诱发人淋巴细胞白血病细胞株Molt－4细胞和巨噬细胞株Ana－1细胞的细胞调亡。估算了浓缩235U在不同阶段培养细胞中的辐射累积吸收剂量。通过电镜对免疫细胞的形态观察，发现Molt－4和Ana－1细胞在受235U内照射作用下可呈现核染质边聚，DNA链断裂和膜包裹的凋亡小体形成。对Molt－4和Ana－1细胞的DNA抽提，进行DNA琼脂糖凝胶电泳也显示出阶梯状条带形成的细胞调亡特征。从而证实了浓缩235U内照射可导致免疫细胞Molt－4和Ana－1细胞的凋亡发生。     

基于Adams的摆杆输送机动力学仿真分析

采用Adams脚本语言建模,自动完成摆杆输送机整体系统的轨道、链条、摆杆和工件之间的装配约束和载荷边界条件的设定等.对某卡车白车身涂装过程进行动力学仿真分析,求得系统整体运行时所需的驱动力大小、链节间的相互作用力和进行静力学分析所需的载荷条件等,分析结果可指导摆杆输送机的整体设计.