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101.
Samantha Cheung Victoria McCarl Andrew J. Holmes Nicholas V. Coleman Peter J. Rutledge 《Applied microbiology and biotechnology》2013,97(3):1131-1140
Mycobacterium strain NBB4 is an ethene-oxidising micro-organism isolated from estuarine sediments. In pursuit of new systems for biocatalytic epoxidation, we report the capacity of strain NBB4 to convert a diverse range of alkene substrates to epoxides. A colorimetric assay based on 4-(4-nitrobenzyl)pyridine) has been developed to allow the rapid characterisation and quantification of biocatalytic epoxide synthesis. Using this assay, we have demonstrated that ethene-grown NBB4 cells epoxidise a wide range of alkenes, including terminal (propene, 1-butene, 1-hexene, 1-octene and 1-decene), cyclic (cyclopentene, cyclohexene), aromatic (styrene, indene) and functionalised substrates (allyl alcohol, dihydropyran and isoprene). Apparent specific activities have been determined and range from 2.5 to 12.0 nmol min?1 per milligram of cell protein. The enantioselectivity of epoxidation by Mycobacterium strain NBB4 has been established using styrene as a test substrate; (R)-styrene oxide is produced in enantiomeric excesses greater than 95%. Thus, the ethene monooxygenase of Mycobacterium NBB4 has a broad substrate range and promising enantioselectivity, confirming its potential as a biocatalyst for alkene epoxidation. 相似文献
102.
母胎耐受机制的阐明,将为器官移植免疫耐受方案的研究提供重要启示.本研究旨在阐明妊娠状态对父系来源移植皮片的存活是否有保护作用.2月龄雌性C57BL/6小鼠和2~4月龄BALB/c雄性小鼠同笼受孕.采用流式细胞技术确定妊娠过程中调节性T细胞(Treg)比例的时间变化规律.以单向混合淋巴细胞反应(MLR)手段比较研究妊娠对于父系来源脾细胞刺激后产生的增殖反应的影响.通过同种异体小鼠全厚皮片移植模型,观察妊娠对于父系来源移植皮片的存活是否具有保护作用.并用分子生物学技术研究此种效能的可能机制.结果显示,C57BL/6小鼠妊娠过程中,Treg占CD4+T细胞的比例从妊娠前的4.2%逐渐上升,受孕8天左右达到高峰值(6.8%),此后开始下降并逐渐回复至基线水平.MLR结果表明,针对父系来源脾细胞的刺激,妊娠组较对照组呈现显著的低反应性,其平均刺激指数分别是7.8和13.6(P〈0.05).定量PCR研究表明,血红素加氧酶-1和吲哚胺2,3双加氧酶mRNA在胎盘高表达,在脾脏低表达(P〈0.05).父系来源的移植皮片的平均存活时间在妊娠组和非妊娠组分别是7.67和7.08天,无统计学差异(P〉0.05).由此认为,在小鼠妊娠过程中,尽管出现了具有免疫抑制功能的Treg的比例增加,尽管有针对父系来源刺激细胞的较低的MLR反应性,但是单次妊娠对于父系来源的移植皮片的存活,在本研究条件下,未能显示具有统计学意义的保护作用. 相似文献
103.
本文构建了相当于大熊猫10倍基因组覆盖度的BAC文库, 并随机挑选了其中9个BAC进行测序和组装, 9个BAC的选择满足更多基因更少重复序列的原则. 这9个BAC的组装将为评估基于新一代Illumina GA测序技术的大熊猫全基因组测序及组装的准确性提供有效资源. 运用同源比对和从头预测的方法, 对9个BAC, 共约878 kb的序列进行了基因和重复序列的注释以及进化分析. 一共预测到12个蛋白编码基因, 其中, 7个基因匹配到同源基因的功能注释. 这7个基因平均大小约41 kb, 编码区平均大小约1.2 kb, 每个基因平均约含6个外显子. 同时预测到7个tRNA基因. 大约27%的序列被注释为重复序列. 同时, 基于邻接法, 构建了包含人、小鼠、狗、猫以及大熊猫5个物种的物种进化树, 结果显示狗的基因与其他4个物种相比距大熊猫最近. 本实验结果提供了大熊猫9个BAC的详细序列及注释信息, 为对大熊猫的研究提供了数据资源. 相似文献
104.
Background
The impact of circle of Willis anatomical variation upon the presentation of stroke is probably underrecognised. 相似文献105.
Steenvoorden MM Tolboom TC van der Pluijm G Löwik C Visser CP DeGroot J Gittenberger-DeGroot AC DeRuiter MC Wisse BJ Huizinga TW Toes RE 《Arthritis research & therapy》2006,8(6):R165-10
The healthy synovial lining layer consists of a single cell layer that regulates the transport between the joint cavity and the surrounding tissue. It has been suggested that abnormalities such as somatic mutations in the p53 tumor-suppressor gene contribute to synovial hyperplasia and invasion in rheumatoid arthritis (RA). In this study, expression of epithelial markers on healthy and diseased synovial lining tissue was examined. In addition, we investigated whether a regulated process, resembling epithelial to mesenchymal transition (EMT)/fibrosis, could be responsible for the altered phenotype of the synovial lining layer in RA. Synovial tissue from healthy subjects and RA patients was obtained during arthroscopy. To detect signs of EMT, expression of E-cadherin (epithelial marker), collagen type IV (indicator of the presence of a basement membrane) and alpha-smooth muscle actin (alpha-sma; a myofibroblast marker) was investigated on frozen tissue sections using immunohistochemistry. Fibroblast-like synoviocytes (FLSs) from healthy subjects were isolated and subjected to stimulation with synovial fluid (SF) from two RA patients and to transforming growth factor (TGF)-beta. To detect whether EMT/fibrotic markers were increased, expression of collagen type I, alpha-sma and telopeptide lysylhydroxylase (TLH) was measured by real time PCR. Expression of E-cadherin and collagen type IV was found in healthy and arthritic synovial tissue. Expression of alpha-sma was only found in the synovial lining layer of RA patients. Stimulation of healthy FLSs with SF resulted in an upregulation of alpha-sma and TLH mRNA. Collagen type I and TLH mRNA were upregulated after stimulation with TGF-beta. Addition of bone morphogenetic protein (BMP)-7 to healthy FLS stimulated with SF inhibited the expression of alpha-sma mRNA. The finding that E-cadherin and collagen type IV are expressed in the lining layer of healthy and arthritic synovium indicates that these lining cells display an epithelial-like phenotype. In addition, the presence of alpha-sma in the synovial lining layer of RA patients and induction of fibrotic markers in healthy FLSs by SF from RA patients indicate that a regulated process comparable to EMT might cause the alteration in phenotype of RA FLSs. Therefore, BMP-7 may represent a promising agent to counteract the transition imposed on synoviocytes in the RA joint. 相似文献
106.
107.
108.
利用重组自交系群体对黄瓜侧枝相关性状进行QTL定位分析 总被引:4,自引:0,他引:4
侧枝与黄瓜(Cucumis sativus)产量有密切关系. 本实验利用侧枝长势较弱、萌发较早的华北类型品系S94和侧枝长势较强、萌发较晚的欧洲类型品系S06构建的224个F6:7家系进行黄瓜侧枝相关性状的研究. 利用已构建的重组自交系群体遗传图谱, 使用软件WinQTLCart 2.5进行复合区间定位. 在2006年秋和2007年春两季, 共检测到4个侧枝相关性状(侧枝均长LBAL、侧枝总长LBTL、侧枝数目LBN和第一侧枝节位FLBN)的36个QTL, 单个QTL的贡献率在3.1%(lbtl2.1, 春季)~32.3%(lbn2.3, 春季)之间. 结果显示, 4个不同性状的11个QTL (lbal1.1, lbtl1.1, lbn1.2, flbn1.2等)在两季中都聚集在第1连锁群e23m18d~ME23EM6c之间(7.4 cM), 并且在第2连锁群的S94A1~ME4SA4a之间(13.9 cM)也检测到了4个不同性状的15个QTL (lbal2.1, lbtl2.1, lbn2.1和flbn2.1等). 两季共有21个QTL贡献率超过10%, 其中lbn2.3的贡献率(春季32.3%, LOD=18.4)为最大, lbtl1.3(秋季26.2%, LOD=17.4; 春季26.9%, LOD=17.9)在两季的位置和贡献率都稳定. 这些基因座为将来进行QTL精细定位提供了参考, 同时利用其紧密连锁(<10 cM)的特异标记(CMBR40, F, CS30, S94A1, CSWTA11B)可进行黄瓜侧枝性状的分子标记辅助育种. 相似文献
109.
Greenhouse gas mitigation in agriculture 总被引:7,自引:0,他引:7
Smith P Martino D Cai Z Gwary D Janzen H Kumar P McCarl B Ogle S O'Mara F Rice C Scholes B Sirotenko O Howden M McAllister T Pan G Romanenkov V Schneider U Towprayoon S Wattenbach M Smith J 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2008,363(1492):789-813
Agricultural lands occupy 37% of the earth's land surface. Agriculture accounts for 52 and 84% of global anthropogenic methane and nitrous oxide emissions. Agricultural soils may also act as a sink or source for CO2, but the net flux is small. Many agricultural practices can potentially mitigate greenhouse gas (GHG) emissions, the most prominent of which are improved cropland and grazing land management and restoration of degraded lands and cultivated organic soils. Lower, but still significant mitigation potential is provided by water and rice management, set-aside, land use change and agroforestry, livestock management and manure management. The global technical mitigation potential from agriculture (excluding fossil fuel offsets from biomass) by 2030, considering all gases, is estimated to be approximately 5500-6000Mt CO2-eq.yr-1, with economic potentials of approximately 1500-1600, 2500-2700 and 4000-4300Mt CO2-eq.yr-1 at carbon prices of up to 20, up to 50 and up to 100 US$ t CO2-eq.-1, respectively. In addition, GHG emissions could be reduced by substitution of fossil fuels for energy production by agricultural feedstocks (e.g. crop residues, dung and dedicated energy crops). The economic mitigation potential of biomass energy from agriculture is estimated to be 640, 2240 and 16 000Mt CO2-eq.yr-1 at 0-20, 0-50 and 0-100 US$ t CO2-eq.-1, respectively. 相似文献
110.
Gayathri Govindaraju CA. Jabeena Devadathan Valiyamangalath Sethumadhavan Nivethika Rajaram Arumugam Rajavelu 《Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms》2017,1860(10):1047-1057
In eukaryotes, cytosine methylation regulates diverse biological processes such as gene expression, development and maintenance of genomic integrity. However, cytosine methylation and its functions in pathogenic apicomplexan protozoans remain enigmatic. To address this, here we investigated the presence of cytosine methylation in the nucleic acids of the protozoan Plasmodium falciparum. Interestingly, P. falciparum has TRDMT1, a conserved homologue of DNA methyltransferase DNMT2. However, we found that TRDMT1 did not methylate DNA, in vitro. We demonstrate that TRDMT1 methylates cytosine in the endogenous aspartic acid tRNA of P. falciparum. Through RNA bisulfite sequencing, we mapped the position of 5-methyl cytosine in aspartic acid tRNA and found methylation only at C38 position. P. falciparum proteome has significantly higher aspartic acid content and a higher proportion of proteins with poly aspartic acid repeats than other apicomplexan pathogenic protozoans. Proteins with such repeats are functionally important, with significant roles in host-pathogen interactions. Therefore, TRDMT1 mediated C38 methylation of aspartic acid tRNA might play a critical role by translational regulation of important proteins and modulate the pathogenicity of the malarial parasite. 相似文献