ERdj5 is required as a disulfide reductase for degradation of misfolded proteins in the ER

Membrane and secretory proteins cotranslationally enter and are folded in the endoplasmic reticulum (ER). Misfolded or unassembled proteins are discarded by a process known as ER-associated degradation (ERAD), which involves their retrotranslocation into the cytosol. ERAD substrates frequently contain disulfide bonds that must be cleaved before their retrotranslocation. Here, we found that an ER-resident protein ERdj5 had a reductase activity, cleaved the disulfide bonds of misfolded proteins, and accelerated ERAD through its physical and functional associations with EDEM (ER degradation-enhancing alpha-mannosidase-like protein) and an ER-resident chaperone BiP. Thus, ERdj5 is a member of a supramolecular ERAD complex that recognizes and unfolds misfolded proteins for their efficient retrotranslocation.     

Conversion of wastes into bioelectricity and chemicals by using microbial electrochemical technologies

Waste biomass is a cheap and relatively abundant source of electrons for microbes capable of producing electrical current outside the cell. Rapidly developing microbial electrochemical technologies, such as microbial fuel cells, are part of a diverse platform of future sustainable energy and chemical production technologies. We review the key advances that will enable the use of exoelectrogenic microorganisms to generate biofuels, hydrogen gas, methane, and other valuable inorganic and organic chemicals. Moreover, we examine the key challenges for implementing these systems and compare them to similar renewable energy technologies. Although commercial development is already underway in several different applications, ranging from wastewater treatment to industrial chemical production, further research is needed regarding efficiency, scalability, system lifetimes, and reliability.     

绿色木霉降解稻草秸杆产葡萄糖工艺优化研究

[目的]采用响应曲面法对绿色木霉（Trichodermaviride）降解稻草秸杆产葡萄糖的工艺进行优化研究。[方法]首先通过Plackett-Burman试验从7个发酵参数中筛选出影响葡萄糖产量的3个主要因素,即发酵时间、pH值和料水比。然后利用Box-Behnken试验设计对此3个因素的最佳水平和交互作用进行研究,通过对试验结果的响应面分析得出降解秸秆产葡萄糖的最佳发酵条件。[结果]绿色木霉发酵降解秸秆产葡萄糖的最佳发酵条件为：发酵时间2d,pH值为4.5,料水比2.5%,在此条件下,葡萄糖产量可达191.70mg/g。与优化前相比,葡萄糖产量提高了137.58%。[结论]该研究提高了将稻草纤维素转化成葡萄糖的转化率,降低了生产成本,为后续发酵生产燃料乙醇打下了良好的基础。     

Conversion of zinc oxide nanobelts into superlattice-structured nanohelices

A previously unknown rigid helical structure of zinc oxide consisting of a superlattice-structured nanobelt was formed spontaneously in a vapor-solid growth process. Starting from a single-crystal stiff nanoribbon dominated by the c-plane polar surfaces, an abrupt structural transformation into the superlattice-structured nanobelt led to the formation of a uniform nanohelix due to a rigid lattice rotation or twisting. The nanohelix was made of two types of alternating and periodically distributed long crystal stripes, which were oriented with their c axes perpendicular to each other. The nanohelix terminated by transforming into a single-crystal nanobelt dominated by nonpolar (0110) surfaces. The nanohelix could be manipulated, and its elastic properties were measured, which suggests possible uses in electromechanically coupled sensors, transducers, and resonators.     

甘蔗渣啤酒糟高效转化平菇试验研究

以甘蔗渣为主料,啤酒糟为主要辅料,通过研究姬菇6号、新选700、特抗650和夏抗50菌丝生长速度、长势和生物转化率等指,标优化出比较适合蔗渣栽培的平菇品种和栽培配方。正交实验极差结果显示,影响4个平菇生物转化率的主次因素为啤酒糟麸皮。实验结果表明,添加适宜的麸皮是蔗渣栽培平菇增产的关键;姬菇6号、新选700、特抗650和夏抗50均在配方4(A2B3)上生物转化率最高,即啤酒糟15%、麸皮10%的配方上生物转化率最大,其生物转化率分别为160.06%、140.89%、178.75%和125.87%。结合4个菌株出菇时的农艺性状得出,姬菇6号比较适合以甘蔗渣为主料,啤酒糟为辅料的培养基栽培。     

Conversion of Unc104/KIF1A kinesin into a processive motor after dimerization

Unc104/KIF1A belongs to a class of monomeric kinesin motors that have been thought to possess an unusual motility mechanism. Unlike the unidirectional motion driven by the coordinated actions of the two heads in conventional kinesins, single-headed KIF1A was reported to undergo biased diffusional motion along microtubules. Here, we show that Unc104/KIF1A can dimerize and move unidirectionally and processively with rapid velocities characteristic of transport in living cells. These results suggest that Unc104/KIF1A operates in vivo by a mechanism similar to conventional kinesin and that regulation of motor dimerization may be used to control transport by this class of kinesins.     

连续水热转化甘油为乳酸的研究

为实现由甘油生产乳酸，开发了一套连续水热反应装置，并利用该装置对甘油水热转化为乳酸这一反应的连续过程进行研究.在300 ℃，10 MPa，NaOH 1.250 mol?L-1和碱性水热条件下，反应60 min后，成功实现了水热转化甘油为乳酸并达到近似于间歇式实验的乳酸生成率.实验结果表明，与间歇式实验结果不同，在较高碱浓度下延长反应时间导致乳酸生成率降低；同时，低分子有机酸大量生成，从而显著降低了乳酸生成选择性，这可能与连续热水反应器中的反应管具有较大的比表面积促进了乳酸进一步分解有关.基于实验结果，对该装置提出了更换反应管材质、保护反应管预热段以及两阶段供碱等改进的建议.     

Insights into enzyme function from studies on mutants of dihydrofolate reductase

Kinetic analysis and protein mutagenesis allow the importance of individual amino acids in ligand binding and catalysis to be assessed. A kinetic analysis has shown that the reaction catalyzed by dihydrofolate reductase is optimized with respect to product flux, which in turn is predetermined by the active-site hydrophobic surface. Protein mutagenesis has revealed that specific hydrophobic residues contribute 2 to 5 kilocalories per mole to ligand binding and catalysis. The extent to which perturbations within this active-site ensemble may affect catalysis is discussed in terms of the constraints imposed by the energy surface for the reaction.     

同化玉米芯酸解液为丁醇

[目的]探究用于丙酮丁醇发酵的玉米芯酸解液的制备方法,寻找培养基组分的较佳组合。[方法]以产物丁醇浓度为指标,比较4种不同玉米芯酸解液制备方法。[结果]稀硫酸处理玉米芯后,用Ca（OH）2调节pH,经XAD-4树脂、活性炭处理,可得到13.71 g/L丁醇;利用薄层层析法分析酸解液中主要还原糖是葡萄糖和木糖,经发酵分析可为Clostridium acetobutylicum ATCC824相同利用;经单因素分析,培养基组分较佳组合为：100%玉米芯水解液中,需加入2 g/L的FeSO4,30 g/L的黄豆饼粉,得到丁醇的最高浓度为19.2 g/L。[结论]玉米芯酸解液可用于丁醇发酵,但需去除有毒物。     

Sex Conversion in a Male Vitis vinifera L. by a Kinin

A synthetic (reputed) kinin, SD 8339, at 1000 parts per million in alcohol solution, applied to flower clusters of a male grapevine about 3 weeks before anthesis, completely converted the flower sex from male to hermaphrodite. Indolebutyric acid, 2,3,5-triiodobenzoic acid, 2-chloroethyltrimethylammonium chloride beta-naphthoxyacetic acid, beta-indoleacetic acid, alpha-naphthaleneacetic acid, and gibberellin A(3) failed to modify the sex.     

Control of enzyme activity by an engineered disulfide bond

A novel approach to the control of enzyme catalysis is presented in which a disulfide bond engineered into the active-site cleft of bacteriophage T4 lysozyme is capable of switching the activity on and off. Two cysteines (Thr21----Cys and Thr142----Cys) were introduced by oligonucleotide-directed mutagenesis into the active-site cleft. These cysteines spontaneously formed a disulfide bond under oxidative conditions in vitro, and the catalytic activity of the oxidized (cross-linked) T4 lysozyme was completely lost. On exposure to reducing agent, however, the disulfide bond was rapidly broken, and the reduced (non-cross-linked) lysozyme was restored to full activity. Thus an enzyme has been engineered such that redox potential can be used to control catalytic activity.     

微生物转化玉米秸秆用于饲料生产的研究

为开辟新的饲料资源,在采用混合酶液对玉米秸秆进行初步酶解的基础上,进一步接种混合菌进行固态发酵.接种15 d测定发现,秸秆中木质纤维素各成分降解显著,其中木质素含量由开始的16.8％降至7.3％,纤维素、半纤维素含量也分别由最初的27.2％、39.0％降至13.4％、16.1％;同时固体基质中蛋白质、还原糖含量迅猛提升...     

加入WTO与福建省农产品市场开拓

入世对我省农业发展产生巨大而深远的影响。一方面 ,入世将对我省处于半封闭状态的传统农业和农产品市场带来巨大的冲击 ;另一方面 ,入世对促使我们从国际国内两个市场 ,两种需求和自身比较优势的角度重新调整农业结构 ,大力开拓我省的农产品市场 ,为我省农业未来的持续发展提供新的契机     

Polycomb proteins targeted by a short repeat RNA to the mouse X chromosome

To equalize X-chromosome dosages between the sexes, the female mammal inactivates one of her two X chromosomes. X-chromosome inactivation (XCI) is initiated by expression of Xist, a 17-kb noncoding RNA (ncRNA) that accumulates on the X in cis. Because interacting factors have not been isolated, the mechanism by which Xist induces silencing remains unknown. We discovered a 1.6-kilobase ncRNA (RepA) within Xist and identified the Polycomb complex, PRC2, as its direct target. PRC2 is initially recruited to the X by RepA RNA, with Ezh2 serving as the RNA binding subunit. The antisense Tsix RNA inhibits this interaction. RepA depletion abolishes full-length Xist induction and trimethylation on lysine 27 of histone H3 of the X. Likewise, PRC2 deficiency compromises Xist up-regulation. Therefore, RepA, together with PRC2, is required for the initiation and spread of XCI. We conclude that a ncRNA cofactor recruits Polycomb complexes to their target locus.     

植物AFLP标记转化为特异PCR标记的研究进展

综述植物AFLP标记转化为特异PCR标记的研究进展。