Isolation and identification of granule-associated proteins relevant for poly(3-hydroxyalkanoic acid) biosynthesis in Chromatium vinosum D

Abstract Poly(3-hydroxybutyric acid) granules, which harbored only four major granule-associated proteins as revealed by SDS polyacrylamide gel electrophoresis, were isolated from crude cellular extracts of Chromatium vinosum D by centrifugation in a linear sucrose gradient. N-Terminal amino acid sequence determination identified two proteins of M _r 41 000 and M _{r 40 000} as the phaE _Cv and phaC _Cv translational products, respectively, of C. vinosum D. In a previous study it was shown that both proteins are required for the expression opf poly(3-hydroxyalkanoic acid) synthase activity. The N-terminus of the third protein ( M _r 17 000) exhibited no homology to other proteins. Lysozyme, which was during purification of the granules, exhibited a strong affinity to PHB granules and was identified as the fourth protein enriched with the granules.     

乳液法静电纺丝PLGA组织工程缓释纤维的研究

目的：研究Dextran对蛋白药物的释放影响。方法：将模型蛋白BSA溶解于多糖溶液中,通过W/O乳液法静电纺丝制备缓释纤维。采用MicroBCA法测定该纤维体外释放行为,采用SEC-HPLC检测制备前后蛋白的聚集程度,并与不含多糖的BSA纤维做对照。结果：添加Dextran以后蛋白的包封率由52.68%提高到63.92%,第一天突释不大于药物载量的15%,对蛋白单体的保持达到85%以上。结论：Dextran可以改善一般组织工程纤维中蛋白药物的释放,提高蛋白药物在制剂、贮存、释放过程中的稳定性,增加纤维的载药量。     

Methylglyoxal accumulation de-regulates HoxA5 expression,thereby impairing angiogenesis in glyoxalase 1 knock-down mouse aortic endothelial cells

Impaired angiogenesis leads to long-term complications and is a major contributor of the high morbidity in patients with Diabetes Mellitus (DM). Methylglyoxal (MGO) is a glycolysis byproduct that accumulates in DM and is detoxified by the Glyoxalase 1 (Glo1). Several studies suggest that MGO contributes to vascular complications through mechanisms that remain to be elucidated. In this study we have clarified for the first time the molecular mechanism involved in the impairment of angiogenesis induced by MGO accumulation.Angiogenesis was evaluated in mouse aortic endothelial cells isolated from Glo1-knockdown mice (Glo1KD MAECs) and their wild-type littermates (WT MAECs). Reduction in Glo1 expression led to an accumulation of MGO and MGO-modified proteins and impaired angiogenesis of Glo1KD MAECs. Both mRNA and protein levels of the anti-angiogenic HoxA5 gene were increased in Glo1KD MAECs and its silencing improved both their migration and invasion. Nuclear NF-?B-p65 was increased 2.5-fold in the Glo1KD as compared to WT MAECs. Interestingly, NF-?B-p65 binding to HoxA5 promoter was also 2-fold higher in Glo1KD MAECs and positively regulated HoxA5 expression in MAECs. Consistent with these data, both the exposure to a chemical inhibitor of Glo1 “SpBrBzGSHCp2” (GI) and to exogenous MGO led to the impairment of migration and the increase of HoxA5 mRNA and NF-?B-p65 protein levels in microvascular mouse coronary endothelial cells (MCECs).This study demonstrates, for the first time, that MGO accumulation increases the antiangiogenic factor HoxA5 via NF-?B-p65, thereby impairing the angiogenic ability of endothelial cells.     

Interference elimination of an amperometric glucose biosensor using poly(hydroxyethyl methacrylate) membrane

A permselective membrane fabricated from photo‐cross‐linked poly(hydroxyethyl methacrylate) (pHEMA) was studied as a potential selective membrane that can eliminate electrochemical interferences commonly faced by a hydrogen peroxide‐based biosensor. The quantitative selection of the permselective membrane was based on the permeabilities of hydrogen peroxide and acetaminophen (AC). AC was used as a model of the interfering substance due to its neutral nature. pHEMA membrane with the cross‐linking ratio of 0.043 was found to achieve a selectivity of hydrogen peroxide over AC of 10, while maintaining an acceptable degree of hydrogen peroxide response. A two‐layer glucose biosensor model consisting of glucose oxidase entrapped within a freeze‐thawed poly(vinyl alcohol) matrix and the cross‐linked pHEMA membrane was challenged with AC, ascorbic acid and uric acid. 0.2 mM AC and 0.2 mM ascorbic acid were completely eliminated. However, 0.2 mM uric acid could not be completely eliminated and still gave a bias of approximately 6.6% relative to 5 mM glucose. The results showed that cross‐linked pHEMA was quite promising as an interference eliminating inner membrane.     

The Synergistic Effect of Cation and Anion of an Ionic Liquid Additive for Lithium Metal Anodes

Lithium metal anodes are steadily gaining more attention, as their superior specific capacities and low redox voltage can significantly increase the energy density of rechargeable batteries far beyond those of current Li‐ion batteries. Nonetheless, the relevant technology is still in a premature research stage mainly due to the uncontrolled growth of Li dendrites that ceaselessly cause unwanted side reactions with electrolyte. In order to circumvent this shortcoming, herein, an ionic liquid additive, namely, 1‐dodecyl‐1‐methylpyrrolidinium (Pyr1(12)⁺) bis(fluorosulfonyl)imide (FSI^?), for conventional electrolyte solutions is reported. The Pyr1(12)⁺ cation with a long aliphatic chain mitigates dendrite growth via the combined effects of electrostatic shielding and lithiophobicity, whereas the FSI^? anion can induce the formation of rigid solid–electrolyte interphase layers. The synergy between the cation and anion significantly improves cycling performance in asymmetric and symmetric control cells and a full cell paired with an LiFePO₄ cathode. The present study provides a useful insight into the molecular engineering of electrolyte components by manipulating the charge and structures of the involved molecules.     

Poly(ADP-ribose) signaling in cell death

Poly(ADP-ribosyl)ation (PARylation) is a reversible protein modification carried out by the concerted actions of poly(ADP-ribose) polymerase (PARP) enzymes and poly(ADP-ribose) (PAR) decomposing enzymes such as PAR glycohydrolase (PARG) and ADP-ribosyl hydrolase 3 (ARH3). Reversible PARylation is a pleiotropic regulator of various cellular functions but uncontrolled PARP activation may also lead to cell death. The cellular demise pathway mediated by PARylation in oxidatively stressed cells has been described almost thirty years ago. However, the underlying molecular mechanisms have only begun to emerge relatively recently. PARylation has been implicated in necroptosis, autophagic cell death but its role in extrinsic and intrinsic apoptosis appears to be less predominant and depends largely on the cellular model used. Currently, three major pathways have been made responsible for PARP-mediated necroptotic cell death: (1) compromised cellular energetics mainly due to depletion of NAD, the substrate of PARPs; (2) PAR mediated translocation of apoptosis inducing factor (AIF) from mitochondria to nucleus (parthanatos) and (3) a mostly elusive crosstalk between PARylation and cell death/survival kinases and phosphatases. Here we review how these PARP-mediated necroptotic pathways are intertwined, how PARylation may contribute to extrinsic and intrinsic apoptosis and discuss recent developments on the role of PARylation in autophagy and autophagic cell death.     

Ethers Illume Sodium‐Based Battery Chemistry: Uniqueness,Surprise, and Challenges

Sodium‐ion batteries (SIBs) have the potential to be practically applied in large‐scale energy storage markets. The rapid progress of SIBs research is primarily focused on electrodes, while electrolytes attract less attention. Indeed, the improvement of electrode performance is arguably correlated with the electrolyte optimization. In conventional lithium‐ion batteries (LIBs), ether‐based electrolytes are historically less practical owing to the insufficient passivation of both anodes and cathodes. As an important class of aprotic electrolytes, ethers have revived with the emerging lithium‐sulfur and lithium‐oxygen batteries in recent years, and are even booming in the wave of SIBs. Ether‐based electrolytes are unique to enabling these new battery chemistries in terms of producing stable ternary graphite intercalation compounds, modifying anode solid electrolyte interphases, reducing the solubility of intermediates, and decreasing polarization. Better still, ether‐based electrolytes are compatible with specific inorganic cathodes and could catalyze the assembly of full SIBs prototypes. This Research News article aims to summarize the recent critical reports on ether‐based electrolytes in sodium‐based batteries, to unveil the uniqueness of ether‐based electrolytes to advancing diverse electrode materials, and to shed light on the viability and challenges of ether‐based electrolytes in future sodium‐based battery chemistries.     

Modification of cellulosic fabric using polyvinyl alcohol, part-II: Colorfastness properties

A series of aqueous solutions of poly(vinyl alcohol) of various commercial products were prepared and applied onto the surfaces of cotton and blends of cotton/polyester fabrics. Fourier transform infrared spectrophotometer was used to confirm the molecular structure of the polyvinyl alcohol used. Performance tests such as colorfastness to rubbing (dry and wet) and colorfastness to washing were determined. The controlling variables affecting the performance properties of the finished substrate such as post-treatment with poly(vinyl alcohol) of various commercial trades, concentration and dilutions were studied. Crocking, washing and hue change of the treated dyed and printed fabrics is accompanied by the formation of semi-inter-penetrated network structure due to the presence of the hydroxyl (-OH) groups which make feasible to a number of grafting and physical cross linking reactions of polymer backbone.     

Heparin localization and fine structure regulate Burkitt's lymphoma growth

Burkitt's lymphoma (BL) is a B-cell malignancy associated with the Epstein-Barr virus (EBV). Mounting evidence has implicated heparan sulfate proteoglycans and heparan sulfate-like glycosaminoglycans (HSGAGs) in the initiation, severity, and progression of the malignancy. The importance of HSGAGs in regulating BL cell growth was therefore examined. Extracellular exogenous heparin inhibited cell growth >30%, while heparin internalized with poly(beta-amino ester)s promoted proliferation up to 58%. The growth-modulating effects of heparin and internalized heparin were dependent on cell surface HSGAGs, PI3K, and Erk/Mek. Treatment of cells with protamine sulfate or with heparinases potently inhibited proliferation, with the greatest effects induced by heparinase I. Cell surface HSGAGs therefore play an important role in regulating BL proliferation and may offer a potential target for therapeutic intervention.     

A new shuttle vector for gene expression in biopolymer-producing Ralstonia eutropha

Ralstonia eutropha (formerly Alcaligenes eutrophus) is a fascinating microorganism with a great scientific importance and an immense commercial potential. A new genetic transformation system for the organism would greatly facilitate the biological study and molecular engineering of this organism. We report here a versatile gene expression method for the genetic engineering of R. eutropha. This method, based on a simplified electroporation protocol, uses a recombinant plasmid, pBS29-P2, containing a Pseudomonas syringae promoter (P2) and two antibiotic-resistance markers (i.e., genes coding for kanamycin (Km)- and tetracycline (Tc)-resistance). Using this method, we successfully achieved transformation of wild-type R. eutropha and its poly(hydroxyalkanoate)-negative mutant, R. eutropha PHB⁻4, with various pBS29-P2-based recombinants. A transformation frequency as high as 4 × 10³ Km-resistance colonies/μg DNA was obtained per electroporation experiment. We further demonstrated the successful expression of a heterologous gene coding for green-fluorescent-protein by fluorescence measurement. In addition, our results indicated the expression of a truncated but active Streptomyces coelicolor α-galactosidase in R. eutropha.