V2O5 Nano‐Electrodes with High Power and Energy Densities for Thin Film Li‐Ion Batteries

Nanostructured V₂O₅ thin films have been prepared by means of cathodic deposition from an aqueous solution made from V₂O₅ and H₂O₂ directly on fluorine‐doped tin oxide coated (FTO) glasses followed by annealing at 500°C in air, and studied as film electrodes for lithium ion batteries. XPS results show that the as‐deposited films contained 15% V⁴⁺, however after annealing all the vanadium is oxidized to V⁵⁺. The crystallinity, surface morphology, and microstructures of the films have been investigated by means of XRD, SEM, and AFM. The V₂O₅ thin film electrodes show excellent electrochemical properties as cathodes for lithium ion intercalation: a high initial discharge capacity of 402 mA h g^?1 and 240 mA h g^?1 is retained after over 200 cycles with a discharging rate of 200 mA g^?1 (1.3 C). The specific energy density is calculated as 900 W h kg^?1 for the 1^st cycle and 723 W h kg^?1 for the 180^th cycle when the films are tested at 200 mA g^?1 (1.3 C). When discharge/charge is carried out at a high current density of 10.5 A g^?1 (70 C), the thin film electrodes retain a good discharge capacity of 120 mA h g^?1, and the specific power density is over 28 kW kg^?1.     

<Emphasis Type="Italic">In vitro</Emphasis> adventitious shoot organogenesis and plant regeneration from seedling explants of <Emphasis Type="Italic">Albizia odoratissima</Emphasis> L.f. (Benth.)

Epicotyl, petiole, and cotyledon explants derived from 14-d-old seedlings of Albizia odoratissima were cultured on Murashige and Skoog (MS) basal medium supplemented with different concentrations of either 6-benzylaminopurine (BAP) solely or in combination with 0.5 μM naphthalene-3-acetic acid (NAA). The percentage of shoot regeneration and the number of shoots regenerated varied significantly depending on the type of explants used, the concentration of plant growth regulators, and the orientation of explants on the culture medium. The best response in terms of the percentage of shoot regeneration was obtained from epicotyls cultured horizontally on MS medium supplemented with 5 μM BAP, whereas the highest number of shoots per responding explant was recorded on medium containing 2.5 μM BAP and 0.5 μM NAA. Successful rooting was achieved by placing the microshoots onto MS medium containing 25 μM indole-3-butyric acid (IBA) for 24 h first, then transferring to the same medium without IBA. Of the various substrates tested, vermiculite was the best for plant acclimatization, as 75% of the plants survived and became established.     

禽多杀性巴氏杆菌C48-3株ompH基因敲除突变株的构建及其生物学功能

[目的]探讨ompH基因在禽多杀性巴氏杆菌致病过程中的作用.[方法]利用同源重组原理构建中间为四环素抗性基因,两侧为ompH基因上下游同源序列同源的敲除载体pWSK29△ompH,将敲除载体电击转入C48-3株感受态细胞中,通过四环素抗性和菌落PCR筛选ompH基因的敲除突变株,并通过组合PCR、逆转录PCR和DNA测序对突变株进行验证.用生物学功能实验比较野生株、互补株和突变株在生长速率、荚膜结构、粘着能力和致病性等方面的差异.[结果]组合PCR、逆转录PCR和DNA测序结果证实ompH基因的敲除突变株C48-3△ompH构建成功,电镜观察结果证实ompH基因的缺陷影响细菌的荚膜合成能力,粘附实验结果显示与野生株C48-3和互补株C48-3C相比突变株C48-3△ompH对CEF细胞的粘附能力显著降低(P＜0.01),而小鼠毒力实验结果表明突变株C48-3△ompH的致病性相对减弱.[结论]本实验构建的突变株C48-3△ompH,为进一步研究多杀性巴氏杆菌的致病机理奠定基础.     

基于应用能力培养的微生物学教学内容优化

微生物学作为生物学科的重要组成部分,是诸多专业的专业基础课程,在不同层次、不同类型、不同专业的高校,其教学基本遵循相同或相似的注重课程理论体系的经典教学模式,该模式不利于普通地方院校本科生应用能力的培养。为此,笔者根据微生物学科研项目思路的构建程序和微生物学实际应用的关键操作技术,以实验项目选择和实验项目顺序调整为突破口,优化微生物学理论和实验教学内容,使两者相辅相成融为一体,以充分发挥专业基础课程在培养学生应用能力方面的作用。     

Cellular Source and Mechanisms of High Transcriptome Complexity in the Mammalian Testis

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林可链霉菌黑色素生物合成基因的克隆与表达

以pIJ702的melCl－C2基因为探针杂交林可链霉菌（Streptomyceslincolnensis）78－11染色体DNA,呈现出3．2kb的BamHI片段和2．6kb的SphI片段等一系列阳性条带。构建了含3．0～3．5kbBamHI片段的林可链霉菌78-11基因文库,从中分离克隆了黑色素生物合成基因melCl和melC2,并测定了含有mel基因的重组子pRSB336插入片段的全部DNA顺序。3152bpBamHI片段含有5个开放阅读框架,其中melCl和melC2与链霉菌属三个种的相应基因具有较高的同源性。此外,林可链霉菌78－11的melC2基因产物与人和鼠的酪氨酸酶轻微同源,分别为17．3％和24．5％。种种迹象表明,melCl、melC2和orf3组成黑色素生物合成操纵子结构。为了进一步鉴定上述克隆的林可链霉菌78-11黑色素生物合成基因,构建了分别含有新霉素抗性基因启动子和正反方向mel基因的重组质粒pPZ518和pPZ519,并转化变铅青链霉菌TK23。随机挑选的12个pPZ518转化子在R2YE培养基上均能分泌淡褐色色素,而所有的pPZ519和pES1转化子则都呈白色。     

Regulation of neural progenitor cell state by ephrin-B

Maintaining a balance between self-renewal and differentiation in neural progenitor cells during development is important to ensure that correct numbers of neural cells are generated. We report that the ephrin-B-PDZ-RGS3 signaling pathway functions to regulate this balance in the developing mammalian cerebral cortex. During cortical neurogenesis, expression of ephrin-B1 and PDZ-RGS3 is specifically seen in progenitor cells and is turned off at the onset of neuronal differentiation. Persistent expression of ephrin-B1 and PDZ-RGS3 prevents differentiation of neural progenitor cells. Blocking RGS-mediated ephrin-B1 signaling in progenitor cells through RNA interference or expression of dominant-negative mutants results in differentiation. Genetic knockout of ephrin-B1 causes early cell cycle exit and leads to a concomitant loss of neural progenitor cells. Our results indicate that ephrin-B function is critical for the maintenance of the neural progenitor cell state and that this role of ephrin-B is mediated by PDZ-RGS3, likely via interacting with the noncanonical G protein signaling pathway, which is essential in neural progenitor asymmetrical cell division.     

Mechanical Signaling on the Single Protein Level Studied Using Steered Molecular Dynamics

Efficient communication between the cell and its external environment is of the utmost importance to the function of multicellular organisms. While signaling events can be generally characterized as information exchange by means of controlled energy conversion, research efforts have hitherto mainly been concerned with mechanisms involving chemical and electrical energy transfer. Here, we review recent computational efforts addressing the function of mechanical force in signal transduction. Specifically, we focus on the role of steered molecular dynamics (SMD) simulations in providing details at the atomic level on a group of protein domains, which play a fundamental role in signal exchange by responding properly to mechanical strain. We start by giving a brief introduction to the SMD technique and general properties of mechanically stable protein folds, followed by specific examples illustrating three general regimes of signal transfer utilizing mechanical energy: purely mechanical, mechanical to chemical, and chemical to mechanical. Whenever possible the physiological importance of the example at hand is stressed to highlight the diversity of the processes in which mechanical signaling plays a key role. We also provide an overview of future challenges and perspectives for this rapidly developing field.     

A Simple Allele-Specific PCR Assay for Detecting <Emphasis Type="Italic">FAD2</Emphasis> Alleles in Both A and B Genomes of the Cultivated Peanut for High-Oleate Trait Selection

In cultivated tetraploid peanut (2n = 4x = 40, AABB), the conversion of oleic acid to linoleic acid is mainly catalyzed by the Δ¹² fatty acid desaturase (FAD). Two homoeologous genes (FAD2A and FAD2B) encoding for the desaturase are located on the A and B genomes, respectively. Abolishing or reducing the desaturase activity by gene mutation can significantly increase the oleic acid/linoleic acid ratio. F435-derived high-oleate peanut cultivars contain two key mutations within the Δ¹² fatty acid desaturase gene which include a 1-bp substitution of G:C→A:T in the A genome and a 1-bp insertion of A:T in the B genome. Both of these mutations contribute to abolishing or reducing the desaturase activity, leading to accumulation of oleate versus linoleate. Currently, detection of FAD2 alleles can be achieved by a cleaved amplified polymorphic sequence marker for the A genome and a real-time polymerase chain reaction (PCR) marker for the B genome; however, detection of these key mutations has to use different assay platforms. Therefore, a simple PCR assay for detection of FAD2 alleles on both genomes was developed by designing allele-specific primers and altering PCR annealing temperatures. This assay was successfully used for detecting FAD2 alleles in peanut. Gas chromatography (GC) was used to determine fatty acid composition of PCR-assayed genotypes. The results from the PCR assay and GC analysis were consistent. This PCR assay is quick, reliable, economical, and easy to use. Implementation of this PCR assay will greatly enhance the efficiency of germplasm characterization and marker-assisted selection of high oleate in peanut.     

Rho kinase inhibitor Y-27632 and Accutase dramatically increase mouse embryonic stem cell derivation

Although it has been 30 yr since the development of derivation methods for mouse embryonic stem (ES) cells, the biology of derivation of ES cells is poorly understood and the efficiency varies dramatically between cell lines. Recently, the Rho kinase inhibitor Y-27632 and the cell dissociation reagent Accutase were reported to significantly inhibit apoptosis of human ES cells during passaging. Therefore, in the current study, C57BL/6×129/Sv mouse blastocysts were used to evaluate the effect of the combination of the two reagents instead of using the conventional 129 line in mouse ES cell derivation. The data presented in this study suggests that the combination of Y-27632 and Accutase significantly increases the efficiency of mouse ES cell derivation; furthermore, no negative side effects were observed with Y-27632 and Accutase treatment. The newly established ES cell lines retain stable karyotype, surface markers expression, formed teratomas, and contributed to viable chimeras and germline transmission by tetraploid complementation assay. In addition, Y-27632 improved embryoid body formation of ES cells. During ES cell microinjection, Y-27632 prevented the formation of dissociation-induced cell blebs and facilitates the selection and the capture of intact cells. The methods presented in this study clearly demonstrate that inhibition of Rho kinase with Y-27632 and Accutase dissociation improve the derivation efficiently and reproducibility of mouse ES cell generation which is essential for reducing variability in the results obtained from different cell lines.