Quantitative trait loci that harbor genes regulating muscle size in (MRL/MPJ x SJL/J) F(2) mice

The genetic mechanisms that determine muscle size have not been elucidated, even though it is a key musculoskeletal parameter that reflects muscle strength. In this study, we performed a high-density genome-wide scan using 633 (MRL/MPJ × SJL/J) F₂ intercross 7-week-old mice to identify quantitative trait loci (QTL) involved in the determination of muscle size. Significant QTL were identified for muscle size and body length. Muscle size (adjusted by body length) QTL were identified on chromosomes 7, 9, 11, 14 (two QTL) and 17, which together explained 19.2% of phenotypic variance in F₂ mice, while body length QTL were located on chromosome 2 (two QTL), 9, 11 and 17 which accounted for 28.3% of phenotypic variance in F₂ mice. Three significant epistatic interactions between different QTL positions from muscle size and body length were identified (P <0.01) on chromosomes 2, 9, 14 and 17, which explained 16.1% of the variance in F₂ mice. Electronic Publication     

用ISSR分子标记鉴别东北地区黑木耳生产菌株的研究

利用ISSR分子标记对东北地区黑木耳生产菌株进行了分子鉴别,结果表明在选用的20个UBC-ISSR引物中,有10个引物能对供试的27个黑木耳菌株基因组DNA进行扩增,获得的指纹图谱清晰稳定、多态性强。用NTSYS软件进行聚类分析,相似水平在0.75时,可将27个供试黑木耳菌株分为3个组群。研究结果说明ISSR分子标记,可以有效地用于黑木耳生产菌株快速准确鉴别,是黑木耳指纹图谱分析的理想手段。     

Genome-scale metabolic models as platforms for strain design and biological discovery

Genome-scale metabolic models (GEMs) have been developed and used in guiding systems’ metabolic engineering strategies for strain design and development. This strategy has been used in fermentative production of bio-based industrial chemicals and fuels from alternative carbon sources. However, computer-aided hypotheses building using established algorithms and software platforms for biological discovery can be integrated into the pipeline for strain design strategy to create superior strains of microorganisms for targeted biosynthetic goals. Here, I described an integrated workflow strategy using GEMs for strain design and biological discovery. Specific case studies of strain design and biological discovery using Escherichia coli genome-scale model are presented and discussed. The integrated workflow presented herein, when applied carefully would help guide future design strategies for high-performance microbial strains that have existing and forthcoming genome-scale metabolic models.     

绿色荧光蛋白基因原核表达载体的构建及其在昆虫肠道短短芽孢杆菌和苏云金芽孢杆菌中的表达

【目的】构建带有苏云金芽孢杆菌cry3a基因非芽孢依赖启动子和绿色荧光蛋白基因gfp(Green Fluorescent Protein)的原核表达载体,并转化从桑粒肩天牛幼虫肠道分离的两株常驻细菌短短芽孢杆菌CQUBb和苏云金芽孢杆菌CQUBt,以检测cry3a启动子在昆虫肠道常驻菌中的启动子活性,获得GFP标记菌株,为常驻菌在昆虫幼虫肠道中的定殖情况和杀虫工程菌的构建奠定基础。【方法】采用重叠延伸PCR将cry3a基因启动子和gfp基因进行融合,并与pHT304载体连接构建重组质粒pHT3AG,获得的重组质粒以电脉冲转化肠道常驻菌短短芽孢杆菌CQUBb和苏云金芽孢杆菌CQUBt,于可见光和荧光显微镜下观察荧光并通过SDS-PAGE分析重组菌株的蛋白表达情况,然后对重组菌株进行生长动力学分析和稳定性测试。【结果】重组菌在营养期大量组成型表达GFP,经电泳分离在凝胶上出现约29kDa的特异蛋白条带;重组菌生长曲线与出发菌没有显著差异,说明外源质粒未对宿主菌的生长带来明显不利影响;抗性条件下传代30次后两菌株外源质粒稳定性仍可达95%、67%;两个菌株比较,CQUBb比CQUBt质粒转化率高、重组菌GFP表达时间长、表达量大,并且重组菌株稳定性好。【结论】成功地将cry3a基因核心启动子和gfp基因转入桑粒肩天牛幼虫肠道常驻菌,实现了该启动子在Bt之外的菌株中发挥作用,构建了两个GFP标记菌株;重组基因工程菌株表达量大,稳定性好,可以用作昆虫肠道内微生态研究和芽孢杆菌表达系统以及杀虫菌株的构建。     

The Multifaceted Benefits of Protein Co-expression in Escherichia coli

We report here that the expression of protein complexes in vivo in Escherichia coli can be more convenient than traditional reconstitution experiments in vitro. In particular, we show that the poor solubility of Escherichia coli DNA polymerase III ε subunit (featuring 3’-5’ exonuclease activity) is highly improved when the same protein is co-expressed with the α and θ subunits (featuring DNA polymerase activity and stabilizing ε, respectively). We also show that protein co-expression in E. coli can be used to efficiently test the competence of subunits from different bacterial species to associate in a functional protein complex. We indeed show that the α subunit of Deinococcus radiodurans DNA polymerase III can be co-expressed in vivo with the ε subunit of E. coli. In addition, we report on the use of protein co-expression to modulate mutation frequency in E. coli. By expressing the wild-type ε subunit under the control of the araBAD promoter (arabinose-inducible), and co-expressing the mutagenic D12A variant of the same protein, under the control of the lac promoter (inducible by isopropyl-thio-β-D-galactopyranoside, IPTG), we were able to alter the E. coli mutation frequency using appropriate concentrations of the inducers arabinose and IPTG. Finally, we discuss recent advances and future challenges of protein co-expression in E. coli.     

产酯酶微生物菌种的筛选研究

研究了产酯酶微生物的筛选,包括筛选模型、酶活力检测方法及菌株的分布。对30多份土样以及实验室保存的菌种进行了大量的筛选,以添加三醋酸甘油酯、乳酸乙酯酯类物质对土样等样品富集,采用添加显色剂溴甲酚紫的快速简便平板显色法,观察水解变色圈直径和菌落直径的大小进行初筛。获得两者直径之比相对大的菌株174株,采用平板打孔检测法和摇瓶发酵比色法测酶活力相结合进行复筛,最终得到酯酶活力较高的24株菌株。就初筛和复筛方法及结果加以比较分析,复筛菌株做不同底物的酶活力检测,建立了一个有效、简便及快速的微生物酯酶的筛选模型。并对酯酶产生菌的立体选择专一性进行了初步考察。     

处理印染废水的厌氧折流板反应器中的微生物种群组成及分布规律

设计出一个由12个隔室组成的厌氧折流板反应器(ABR),并将其应用于高浓度、高色度的印染废水生物处理,取得了良好效果。研究着重考察该反应器在处理印染废水过程中不同隔室的微生物种群构成,并分析与印染废水处理效率密切相关的具有脱色功能和苯胺降解功能的两类细菌的分布规律。结果表明,在处理印染废水的ABR反应器中,可培养的优势菌群以芽孢杆菌属(Bacillus)、不动杆菌属(Acinetobacter)、丛毛单胞菌属(Comamonas)、假单胞菌属(Pseudomonas)和水螺菌属(Aquaspirillum)为主,且在ABR的前段、中段及后段隔室中不同种类的优势菌群存在数量差异;好氧及兼性厌氧优势菌群的数量随着废水在ABR隔室中的折流前进而逐渐减少;厌氧微生物的数量变化规律则是先增多,后减少;产甲烷活性在前段隔室中相对较低,后段隔室则相对较高。脱色菌在ABR的前段隔室中分布相对较多,后段隔室中分布相对较少;苯胺降解菌则呈现出在前段隔室中分布相对较少,后段隔室中分布相对较多的规律,这两类功能菌的分布与ABR不同隔室中色度下降、苯胺产生和消减之间密切相关。     

花生根瘤菌优良菌株“305”、“4341”和“4464”的选育

用吖啶橙处理花生根瘤菌菌株“009”,从处理液中分离到1211个衍生菌株,经过初筛与复筛,从中选育出“305”、“4341”和“4464”等侵染结瘤能力较强的菌株。血清学反应证明,这些衍生菌株确系亲株“009”的后代。生理生化特征的鉴定结果显示:亲株与衍生物之间以及各衍生物相互之间的共同性较少,而差异性较大。田间试验结果表明,新选菌株对良种和本地花生都有很强的侵染结瘤能力;在花生的新、老种植区以及不同类型的土壤上,都有显著的增产作用;是适合本省土壤,气候和耕作制度的优良菌株。     

Thermodynamic analysis of amyloid fibril structures reveals a common framework for stability in amyloid polymorphs

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Symbiote-Free Hemoflagellates,Blastocrithidia culicis and Crithidia oncopelti: their Liver Factor Requirement and Serologic Identity*

SYNOPSIS. Several aposymbiotic strains of Blastocrithidia culicis and Crithidia oncopelti were cultivated in Trager's chemically defined medium as well as in a blood broth, both supplemented with 0.25% (v/v) liver extract concentrate. For all such strains, the liver extract was found to serve as an essential growth factor in the defined medium and as growth promoting additive in the blood broth. The active molecules were found to be water-soluble, heat stable, dialyzable, and probably nonlipid fractions. Antisera were developed in rabbit against all the available aposymbiotic strains. An almost total cross-reactivity at very high titers was observed in reciprocal agglutination test using strains with and without the bacterial symbiotes. These results indicate that the loss of the symbiotes does not affect the antigenic identity of B. culicis and C. oncopelti.