Enhancing electrical outputs of the fuel cells with Geobacter sulferreducens by overexpressing nanowire proteins

Protein nanowires are critical electroactive components for electron transfer of Geobacter sulfurreducens biofilm. To determine the applicability of the nanowire proteins in improving bioelectricity production, their genes including pilA, omcZ, omcS and omcT were overexpressed in G. sulfurreducens. The voltage outputs of the constructed strains were higher than that of the control strain with the empty vector (0.470–0.578 vs. 0.355 V) in microbial fuel cells (MFCs). As a result, the power density of the constructed strains (i.e. 1.39–1.58 W m⁻²) also increased by 2.62- to 2.97-fold as compared to that of the control strain. Overexpression of nanowire proteins also improved biofilm formation on electrodes with increased protein amount and thickness of biofilms. The normalized power outputs of the constructed strains were 0.18–0.20 W g⁻¹ that increased by 74% to 93% from that of the control strain. Bioelectrochemical analyses further revealed that the biofilms and MFCs with the constructed strains had stronger electroactivity and smaller internal resistance, respectively. Collectively, these results demonstrate for the first time that overexpression of nanowire proteins increases the biomass and electroactivity of anode-attached microbial biofilms. Moreover, this study provides a new way for enhancing the electrical outputs of MFCs.     

Multistage affinity cross-flow filtration: mathematical modelling and analysis

A multistage affinity cross-flow filtration (mACFF) process for protein purification is proposed. The process is mathematically modelled taking into account a case of rapid equilibrium binding of a target protein to its macroligand. The process performance, i.e., dimensionless breakthrough volume (Q _b ⁺ )and recovery yield (REC) to obtain a desired purity is analysed by computer simulations. The results indicate that Q _b ⁺ increases with the increase of stage number (n) due to the increase of affinity binding efficiency. In addition, REC also increases with the increase of n, especially for lower affinity systems, even though the feed loading is the same as the corresponding breakthrough volume that increases with n. Thus both feed loading and recovery yield can be enhanced by raising the stage number. Incompletely permeable membranes reject the target and contaminant proteins. So they delay the appearance of the breakthrough point and compromise the contaminant washing efficiency. Hence although Q _b ⁺ increases with the increase of membrane rejection coefficient (R), REC decreases when the feed loading equals that of Q _b ⁺ . However, when the feed loading is kept unchanged and equals Q _b ⁺ at R=0, REC does not decrease, but slightly increases with the increase of R. This result indicates that incompletely permeable membranes may also be employed for the mACFF process. In general, the model gives a predictive evaluation of the mACFF process successfully.     

水稻蜡质基因5＇上游区缺失对基因表达的影响

为研究水稻蜡质基因（ｗａｘｙ）５＇上游调控区中存在的顺式作用元件,我们将水稻ｗａｘｙ基因翻译起始声、（ＡＴＧ）５＇上游３．４ｋｂ（－２１１８～＋１２９１ｂＰ）片段经外切核酸酶ＥｘｏⅢ部分酶解,得到一系列５＇端缺失的片段。将这些缺失片段分别与ｇｕｓ基因编码区连接,构建成融合质粒,经ＰＥＧ介导引入水稻原生质体,２６℃培养４８ｈ后,定量测定ＧＵＳ酶活力,并以同时导入的由３５Ｓ启动子指导的荧光素酶（ＬＵＣ）基因表达的酶活力作为内对照。结果表明,ＧＵＳ酶活性随５’上游调控区长度的减少而逐渐减弱。由─８６１ｂｐ缺失至─６４０ｂＰ时,ｇｕｓ基因表达水平有较明显的降低,推测在该区域中可能存在一个顺式作用元件区。     

一例智力低下患者7q~ 标记染色体的来源鉴定

以人类染色体显微切割、PCR技术构建的现有人类染色体特异性和染色体区带特异性探针池作为绘画探针,采用正向染色体绘画技术,结合染色体筛查方法,查明了一例7q~ 标记染色体患者的染色体附加片段来源于3q26→3qter。确定该患者的核型为46,XX,-7, der(7)t(7;3)(7pter→7q32::3q26→3qter)。应用这个策略,能够快速有效地鉴定标记染色体的来源。     

全自动生化分析仪测定血清AST同工酶

应用天冬氨酸氨基转移酶抑制剂“AMANO-3”水解样品中的线粒体型天冬氨酸氨基转移酶同工酶（m-AST）,测定血清中剩余的胞浆型AST同工酶（c-AST）活性,进而与总AST活性相比较并计算出受抑制剂水解的m-AST同工酶活性．由于此方法采用蛋白水解反应破坏m-AST,因此测定方法可直接应用于生化自动分析仪．亦建立了一个适于日立7150分析仪的AST同工酶联合测定方法．其测定和计算出的m-AST同工酶批内CV为3.5％～7.9％;其结果(y)与AST同工酶电泳迁移率(x)相关．y=1.019x-0.489,r＝0.996（n＝30）．测定了113名健康人m-AST和c-AST,其m-AST参考值范围1.64～9.64U/L,x±s＝(5.641±2.013)U/L;c-AST参考值范围5.69～16.81U/L,x±s＝(5.641±2.013)U/L．     

Triton X－100对紫膜蛋白的效应

本文采用同步辐射小角Ｘ射线散射方法研究了用非离子表面活性剂ＴｒｉｔｏｎＸ—１００处理后的嗜盐菌紫膜及其视紫红质蛋白结构的变化。实验结果表明,用不同浓度的ＴｒｉｔｏｎＸ—１００处理紫膜碎片时,紫膜及其蛋白所处的状态有着很大变化。     

中药金樱子的研究应用概况

本文就国内外对中药金樱子的化学成分及其提取分离方法、药理学研究和临麻应用作了综述,为金樱子的综合开发提供依据。