高效合成番茄红素酿酒酵母菌株的构建

番茄红素作为一种高附加价值的萜类化合物已受到国内外研究者的广泛关注。首先对酿酒酵母Saccharomyces cerevisiae模式菌株S288c和YPH499合成番茄红素的能力进行分析比较,结果表明YPH499更适合作为底盘细胞用于番茄红素的合成。随后比较组成型启动子GPDpr、TEF1pr和诱导型启动子GAL1pr、GAL10pr对番茄红素合成的影响,结果发现以GPDpr、TEF1pr作为番茄红素合成途径基因crtE、crt B和crtI的启动子,摇瓶发酵60 h后,番茄红素产量为15.31 mg/L;以GAL1pr和GAL10pr为启动子时,其产量为123.89 mg/L,提高8.09倍。继续改造甲羟戊酸(MVA)途径,过量表达N-末端截短的关键酶基因t HMG1(3-羟基-3-甲基戊二酸单酰辅酶A还原酶),番茄红素产量为265.68 mg/L,单位菌体产量72.79 mg/g。文中所设计构建的异源表达番茄红素合成途径的酿酒酵母菌株单位细胞产量高,可以进一步改造和优化后用于番茄红素的工业化生产。     

免耕套种与秸秆还田对农田生态环境及小麦生长的影响

1　引　　言免耕作为低耗持续农业生产和保护性耕作的一项重要手段,越来越受到国内外学者的重视.在国外,免耕最早是20世纪30年代为防治土壤风蚀而采取的措施,60年代得到迅速发展,且随着研究的不断深入,免耕的作用逐渐扩大[10,18].我国自70年代后期开始免耕的系统研究,在免耕和秸秆覆盖对土壤理化性质、微生物区系及生态环境的影响等方面都有不少报道[2,11,16,17,23].秸秆还田在提高土壤肥力,增加作物产量等方面已被许多研究所证实[3,5～8,12,13,19～21].随着社会和生产的发展,秸秆还田的方式,方法和数量都在不断变化,尤其是部分地区禁烧秸秆…     

Biomass–oxygen gasification in a high-temperature entrained-flow gasifier

The technology associated with indirect biomass liquefaction is currently arousing increased attention, as it could ensure a supply of transportation fuels and reduce the use of petroleum. The characteristics of biomass–oxygen gasification in a bench-scale laminar entrained-flow gasifier were studied in the paper. Experiments were carried out to investigate the influence of some key factors, including reaction temperature, residence time and oxygen/biomass ratio, on the gasification. The results indicated that higher temperature favored H₂ and CO production. Cold gas efficiency was improved by > 10% when the temperature was increased from 1000 to 1400 °C. The carbon conversion increased and the syngas quality was improved with increasing residence time. A shorter residence resulted in incomplete gasification. An optimal residence time of 1.6 s was identified in this study. The introduction of oxygen to the gasifier strengthened the gasification and improved the carbon conversion, but lowered the lower heating value and the H₂/CO ratio of the syngas. The optimal oxygen/biomass ratio in this study was 0.4. The results of this study will help to improve our understanding of syngas production by biomass high-temperature gasification.     

基于AD-AS模型的海岸带生态系统综合承载力评估——以舟山海岸带为例

以舟山海岸带为研究区域,结合采样数据和社会经济发展数据,构建以社会因子、经济因子和自然因子为3个维度因子的海岸带生态系统综合承载力评估的指标体系。并参照经济学中的AD-AS模型,改进成综合总供给-综合总需求模型(SAD-SAS模型),根据生态系统中总供给与总需求之间的平衡关系,来计算舟山海岸带综合承载力量值,并尝试将海岸带综合承载力值的分类标准在原来的基础上分为5类,最后评价其所处的承载力水平。研究结果表明:舟山海岸带综合承载力在2005—2008年时处于微幅上升的阶段,年均增速为6.5%,在2008—2009年开始出现稍微的下降,下降幅度为3%;SAD-SAS模型作为生态学与经济学交叉的模型,为海岸带综合承载力评价提供了一种新思路。     

Effects of Cold and Salicylic Acid Priming on Free Proline and Sucrose Accumulation in Winter Wheat Under Freezing Stress

Journal of Plant Growth Regulation - This study aims to investigate the effects of cold and salicylic acid (SA) priming on osmolytes accumulation in wheat leaves under freezing stress and its...     

液化沙雷氏菌磷脂酶A1的克隆表达及乳糖自诱导发酵

为了利用大肠杆菌高效生产重组磷脂酶,克隆了液化沙雷氏菌磷脂酶A1的编码基因pla,分别使用pET-28a(+)和pET-20b(+)载体,实现了磷脂酶A1在大肠杆菌BL21(DE3)中的功能表达.重组菌利用载体pET-28a(+)在原始信号肽的介导下胞外PLA1酶活达40.8 U/mL,占总酶活的91％.重组菌转接至优化后的发酵诱导培养基:蛋白胨10 g/L,酵母粉5g/L,葡萄糖0.8 g/L,乳糖5 g/L,25 mmol/L Na2HPO4,25 mmol/L KH2PO4和1 mmol/L MgSO4;菌体生长6h后,添加7.5 g/L的甘氨酸,37℃恒温发酵24 h,重组菌胞外PLA1酶活达到128.7 U/mL.     

Interleukin-10 attenuation of collagen-induced arthritis is associated with suppression of interleukin-17 and retinoid-related orphan receptor γt production in macrophages and repression of classically activated macrophages

Introduction

Our objective in the present study was to determine the signaling pathway of interleukin 10 (IL-10) for modulating IL-17 expression in macrophages and the importance of this mediation in collagen-induced arthritis (CIA).

Methods

IL-10-knockout (IL-10^−/−) mice and wild-type (WT) mice were immunized with chicken type II collagen (CII) to induce arthritis. The expression levels of IL-17 and retinoid-related orphan receptor γt (RORγt) in macrophages and joint tissues of IL-10^−/− and WT mice were analyzed by enzyme-linked immunosorbent assay, quantitative RT-PCR (qRT-PCR) and Western blotting. The F4/80 macrophages and positive IL-17-producing macrophages in synovial tissues of the mice were determined by immunohistochemistry. The populations of classically activated macrophage (M1) and alternatively activated macrophage (M2) phenotypes were analyzed by flow cytometry. The expression of genes associated with M1 and M2 markers was analyzed by qRT-PCR.

Results

Compared to WT mice, IL-10^−/− mice had exacerbated CIA development, which was associated with increased production of T helper 17 cell (Th17)/Th1 proinflammatory cytokines and CII-specific immunoglobulin G2a antibody after CII immunization. Macrophages in IL-10^−/− mice had increased amounts of IL-17 and RORγt compared with the amounts in WT mice with CIA. Immunofluorescence microscopy showed that the number of IL-17-producing macrophages in synovial tissues was significantly higher in IL-10^−/− mice than in WT mice. IL-10 deficiency might promote macrophage polarization toward the proinflammatory M1 phenotype, which contributes to the rheumatoid arthritis inflammation response.

Conclusion

IL-10 inhibits IL-17 and RORγt expression in macrophages and suppresses macrophages toward the proinflammatory M1 phenotype, which is important for the role of IL-10 in mediating the pathogenesis of CIA.     

高通量筛选高产酪氨酸的酿酒酵母菌株

酪氨酸是重要的芳香族氨基酸,自身不仅具有重要的营养价值,也是合成香豆素类化合物和黄酮类化合物的重要前体。文中以实验室前期构建的一株解除了酪氨酸反馈抑制的酿酒酵母Saccharomyces cerevisiae LTH0 (ARO4K229L,ARO7G141S,Δaro10,Δzwf1,Δura3) 为出发菌株,异源表达甜菜黄素合成基因DOD和CYP76AD1,使酿酒酵母产生黄色荧光。然后利用紫外诱变和常压室温等离子体 (Atmospheric and room temperature plasma,ARTP) 诱变相结合的方法对上述菌株进行随机诱变,并通过流式细胞仪筛选荧光强度显著提高的突变株。其中突变株LTH2-5-DOD-CYP76AD1在激发波长485 nm、发射波长505 nm处荧光强度为 (5 941±435) AU/OD,比诱变前提高了8.37倍。对诱变后荧光强度提高较多的14株突变株进行发酵生产酪氨酸,胞外酪氨酸产量最高为26.8 mg/L,比出发菌株提高了3.96倍。进一步异源表达约翰逊黄杆菌Flavobacterium johnsoniae来源的酪氨酸解氨酶FjTAL,对香豆酸产量达到119.8 mg/L,比出发菌株LTH0-FjTAL提高了1.02倍。