Preparation of capacitor’s electrode from sunflower seed shell

Series of nanoporous carbons are prepared from sunflower seed shell (SSS) by two different strategies and used as electrode material for electrochemical double-layer capacitor (EDLC). The surface area and pore-structure of the nanoporous carbons are characterized intensively using N₂ adsorption technique. The results show that the pore-structure of the carbons is closely related to activation temperature and dosage of KOH. Electrochemical measurements show that the carbons made by impregnation-activation process have better capacitive behavior and higher capacitance retention ratio at high drain current than the carbons made by carbonization-activation process, which is due to that there are abundant macroscopic pores and less interior micropore surface in the texture of the former. More importantly, the capacitive performances of these carbons are much better than ordered mesoporous carbons and commercial wood-based active carbon, thus highlighting the success of preparing high performance electrode material for EDLC from SSS.     

Optimizing Membrane Protein Overexpression in the Escherichia coli strain Lemo21(DE3)

Escherichia coli BL21(DE3) is widely used to overexpress proteins. In this overexpression host, the gene encoding the target protein is located on a plasmid and is under control of the T7 promoter, which is recognized exclusively by the T7 RNA polymerase (RNAP). The T7 RNAP gene is localized on the chromosome, and its expression is governed by the non-titratable, IPTG-inducible lacUV5 promoter. Recently, we constructed the Lemo21(DE3) strain, which allows improved control over the expression of genes from the T7 promoter. Lemo21(DE3) is a BL21(DE3) strain equipped with a plasmid harboring the gene encoding T7 lysozyme, an inhibitor of the T7 RNAP, under control of the exceptionally well-titratable rhamnose promoter. The overexpression yields of a large collection of membrane proteins in Lemo21(DE3) at different concentrations of rhamnose indicated that this strain may be very suitable for optimizing the production of membrane proteins. However, insight in the mechanism by which optimized expression yields are achieved in Lemo21(DE3) is lacking. Furthermore, whether the overexpressed proteins are suitable for functional and structural studies remains to be tested. Here, we show that in Lemo21(DE3), (i) the modulation of the activity of the T7 RNAP by the T7 lysozyme is key to optimizing the ratio of membrane proteins properly inserted in the cytoplasmic membrane to non-inserted proteins; (ii) maximizing the yields of membrane proteins is accompanied by reduction of the adverse effects of membrane protein overexpression, resulting in stable overexpression; and (iii) produced membrane proteins can be used for functional and structural studies.     

A lectin-coupled, targeted proteomic mass spectrometry (MRM MS) platform for identification of multiple liver cancer biomarkers in human plasma

Aberrantly glycosylated proteins related to liver cancer progression were captured with specific lectin and identified from human plasma by multiple reaction monitoring (MRM) mass spectrometry as multiple biomarkers for hepatocellular carcinoma (HCC). The lectin fractionation for fucosylated protein glycoforms in human plasma was conducted with a fucose-specific aleuria aurantia lectin (AAL). Following tryptic digestion of the lectin-captured fraction, plasma samples from 30 control cases (including 10 healthy, 10 hepatitis B virus [HBV], and 10 cirrhosis cases) and 10 HCC cases were quantitatively analyzed by MRM to identify which glycoproteins are viable HCC biomarkers. A1AG1, AACT, A1AT, and CERU were found to be potent biomarkers to differentiate HCC plasma from control plasmas. The AUROC generated independently from these four biomarker candidates ranged from 0.73 to 0.92. However, the lectin-coupled MRM assay with multiple combinations of biomarker candidates is superior statistically to those generated from the individual candidates with AUROC more than 0.95, which can be an alternative to the immunoassay inevitably requiring tedious development of multiple antibodies against biomarker candidates to be verified. Eventually the lectin-coupled, targeted proteomic mass spectrometry (MRM MS) platform was found to be efficient to identify multiple biomarkers from human plasma according to cancer progression.     

ELISA检测抗-HIV室内质控血清的制备和应用

为了提高抗-HIV的检测质量,进行室内质控以鉴别诊断试剂的质量和控制操作误差,试制了抗-HIV室内质控血清,收集抗-HIV诊断试剂盒中阳性对照血清,采用不同品牌、不同批号的诊断试剂检测后,稀释、分装成低值弱阳性,即为室内质控血清,将质控血清放不同温度下保存,考核其稳定性和精密性,并应用于两厂家各3批试剂的检测,结果试制的室内质控血清在-20℃条件下存放5个月,在4℃条件下存放29天稳定性良好,检测结果稳定,该质控血清适宜作抗-HIV检测室内质控使用。     

Glycated albumin and diabetes mellitus

Background

Diabetes is a growing worldwide problem that is strongly associated with atherosclerosis. Screening and intervention for diabetes in the earliest stages are advocated for the prevention of diabetic complications and cardiovascular disease.

Scope of review

This review gives a background of and discusses the potential clinical utility of glycated albumin (GA) in diabetes.

Major conclusions

GA is a ketoamine formed via a non-enzymatic glycation reaction of serum albumin and it reflects mean glycemia over two to three weeks. GA can be used for patients with anemia or hemoglobinopathies for whom the clinically measured hemoglobin A1c level may be inaccurate. Because both serum and plasma samples can be used, GA can be analyzed from the same samples as common biological markers. GA is a useful marker for the screening of diabetes in a medical evaluation. It can be also used to determine the effectiveness of treatment before initiating or changing medications for diabetic patients. GA is potentially an atherogenic protein in the development of diabetic atherosclerosis.

General significance

GA measurement is useful as part of a routine examination to screen for both diabetes and atherosclerosis. This article is part of a Special Issue entitled Serum Albumin.     

Periodic Forces Trigger a Complex Mechanical Response in Ubiquitin

Mechanical forces govern physiological processes in all living organisms. Many cellular forces, for example, those generated in cyclic conformational changes of biological machines, have repetitive components. In apparent contrast, little is known about how dynamic protein structures respond to periodic mechanical information. Ubiquitin is a small protein found in all eukaryotes. We developed molecular dynamics simulations to unfold single and multimeric ubiquitins with periodic forces. By using a coarse-grained representation, we were able to model forces with periods about 2 orders of magnitude longer than the protein's relaxation time. We found that even a moderate periodic force weakened the protein and shifted its unfolding pathways in a frequency- and amplitude-dependent manner. A complex dynamic response with secondary structure refolding and an increasing importance of local interactions was revealed. Importantly, repetitive forces with broadly distributed frequencies elicited very similar molecular responses compared to fixed-frequency forces. When testing the influence of pulling geometry on ubiquitin's mechanical stability, it was found that the linkage involved in the mechanical degradation of cellular proteins renders the protein remarkably insensitive to periodic forces. We also devised a complementary kinetic energy landscape model that traces these observations and explains periodic-force, single-molecule measurements. In turn, this analytical model is capable of predicting dynamic protein responses. These results provide new insights into ubiquitin mechanics and a potential mechanical role during protein degradation, as well as first frameworks for dynamic protein stability and the modeling of repetitive mechanical processes.     

江西铅山红芽芋脱毒苗球茎愈伤组织诱导及其再生体系的建立

以江西铅山红芽芋脱毒苗为试材,研究不同因素对红芽芋脱毒苗球茎愈伤组织诱导及其再生体系的影响,以期对红芽芋脱毒苗的再生体系进行优化。结果表明,红芽芋脱毒苗球茎愈伤组织诱导的最佳培养基是MS+TDZ 2 mg·L^-1+2,4-D 1 mg·L^-1。红芽芋脱毒苗球茎愈伤组织分化的最佳培养基是MS+TDZ 2 mg·L^-1+NAA 1 mg·L^-1。红芽芋脱毒苗不定芽生根的最佳培养基是1/2MS+NAA 0.5 mg·L^-1+PP₃₃₃ 0.5 mg·L^-1。红芽芋再生苗最好的移栽基质为发酵后的腐锯木屑。红芽芋脱毒苗球茎愈伤组织再生苗移栽时最佳的PP₃₃₃浓度为20～50 mg·L^-1。本试验成功建立了红芽芋脱毒苗球茎愈伤组织的再生体系,为红芽芋脱毒苗转基因的研究和种质创新奠定了基础。     

SIZE VARIATION,GROWTH STRATEGIES,AND THE EVOLUTION OF MODULARITY IN THE MAMMALIAN SKULL

Allometry is a major determinant of within‐population patterns of association among traits and, therefore, a major component of morphological integration studies. Even so, the influence of size variation over evolutionary change has been largely unappreciated. Here, we explore the interplay between allometric size variation, modularity, and life‐history strategies in the skull from representatives of 35 mammalian families. We start by removing size variation from within‐species data and analyzing its influence on integration magnitudes, modularity patterns, and responses to selection. We also carry out a simulation in which we artificially alter the influence of size variation in within‐taxa matrices. Finally, we explore the relationship between size variation and different growth strategies. We demonstrate that a large portion of the evolution of modularity in the mammalian skull is associated to the evolution of growth strategies. Lineages with highly altricial neonates have adult variation patterns dominated by size variation, leading to high correlations among traits regardless of any underlying modular process and impacting directly their potential to respond to selection. Greater influence of size variation is associated to larger intermodule correlations, less individualized modules, and less flexible responses to natural selection.     

Platelet activating factor-induced apoptosis is inhibited by ectopic expression of the platelet activating factor G-protein coupled receptor

The pro-inflammatory lipid mediator platelet activating factor (PAF: 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) accumulates in ischemia, epilepsy, and human immunodeficiency virus-1-associated dementia and is implicated in neuronal loss. The present study was undertaken to establish a role for its G-protein coupled receptor in regulating neurotoxicity. PC12 cells do not express PAF receptor mRNA as demonstrated by northern analysis and RT-PCR. In the absence of the G-protein coupled receptor, PAF (0.1-1 micro m) triggered chromatin condensation, DNA strand breaks, oligonucleosomal fragmentation, and nuclear disintegration characteristic of apoptosis. Lyso-PAF (0.001-1 micro m), the immediate metabolite of PAF, did not elicit apoptotic death. Concentrations of PAF or lyso-PAF that exceeded critical micelle concentration had physicochemical effects on plasma membrane resulting in necrosis. Apoptosis but not necrosis was inhibited by the PAF antagonist BN52021 (1-100 micro m) but not CV3988 (0.2-20 micro m). Ectopic PAF receptor expression protected PC12 transfectants from ligand-induced apoptosis. PAF receptor-mediated protection was inhibited by CV3988 (1 micro m). These data provide empirical evidence that: (i) PAF can initiate apoptosis independently of its G-protein coupled receptor; (ii) PAF signaling initiated by its G-protein coupled receptor is cytoprotective to PC12 cells; (iii) the pro- and anti-apoptotic effects of PAF on PC12 cells can be pharmacologically distinguished using two different PAF antagonists.