Screening and Characterization of Protease from Metagenomic Library of Deep Sea Sediment

提取东太平洋深海沉积物宏基因组dnA,构建了未培养微生物宏基因组文库.该文库平均插入片段30kb以上,含有7000个克隆,含外源dnA总长度约为210Mb.从文库中筛选到18个产胞外蛋白酶的克隆,16SrrnA分析表明,它们分别来源于假单胞菌(PSEudOMOnAS)、寡养单胞菌(STEnOTrOPHOMOnAS)和弧菌(VIbrIO)3个菌属.根据活性大小及来源菌株的16SrrnA序列比较,选择10个蛋白酶进行酶学性质分析,结果表明,它们的最适作用PH值在7~10之间,最适作用温度在10~40℃之间.其中PrO20蛋白酶最适作用温度最低,为10℃;PrO1蛋白酶具有最适作用温度低(20℃)、PH耐受性好、热稳定性较好等特性,具有良好的应用开发潜力.图6参16Metagenomic cosmid library,containing 7 000 clones with more than 30kb inserts and covering about 210Mb metagenomic DNA of uncultured microorganisms from the deep sea sediment of east Pacific,was constructed,and 18 independent clones expressing protease activity were isolated from the library.The analysis of 16S rRNA showed that these proteases originated from Pseudomonas,Stenotrophomonas and Vibrio,respectively.Ten proteases were selected for further study based on the comparison of their activities and 16S rRNA sequence.The results indicated that the optimal pH and temperature for their activities ranged between 7～10 and 10～40℃,respectively.The Pro20 protease had the lowest optimal temperature at 10℃.The Pro1 protease had better potential for exploitation owing to some virtues including high activity at low temperature,better resistant for high pH and temperature.Fig 6,Ref 16国家高技术研究发展计划(“863”计划)项目(No.2007AA091407);中国大洋矿产资源研究开发协会(COMRA)项目(No.DYXM-115-02-2-04);福建省自然科学基金项目(No.2006J0365)资助---

Regulation effect of exogenous nitric oxide on anti-oxidation system of Kandelia candel seedlings treated with NaCl

研究了外源一氧化氮(NO)供体硝普钠(SNP)对NaCl处理下红树植物秋茄(Kan-deliacandel)幼苗叶片中抗氧化酶活性、抗氧化物质及脯氨酸含量的影响。结果表明:NaCl处理下,秋茄幼苗叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)等4种活性氧清除酶的活性均受到明显抑制(P<0.05),SNP可以不同程度地恢复SOD、POD、CAT的活性,但对APX活性影响不大;SNP提高谷胱甘肽(GSH)及类胡萝卜素(Car)的含量,促进脯氨酸含量的上升,显著降低叶片中过氧化氢(H2O2)和丙二醛(MDA)的累积。表明外源NO可以缓解NaCl处理诱导的秋茄幼苗叶片氧化损伤,降低膜脂过氧化水平,有利于秋茄适应盐生环境。By using sodium nitroprusside(SNP)as the donor of exogenous nitric oxide,this paper studied its effects on the antioxidant enzyme activities,anti-oxidation substances,and proline content in the leaves of Kandelia candel seedlings treated with NaCl.The results showed that after treated with NaCl,the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)and ascorbate peroxidase(APX)in K.candel seedling leaves were depressed significantly(P<0.05),while SNP could recover the activities of SOD,POD and CAT to different degrees but showed little effect on APX.SNP increased the contents of glutathione(GSH)and carotenoid(Car),promoted the production of proline,and decreased the accumulation of H2O2 and malondialdehyde(MDA)significantly.It was indicated that SNP could relieve the oxidation damages induced by NaCl via decreasing the level of membrane lipid peroxidation in K.candel leaves,and facilitate K.candel to adapt to saline environment.国家自然科学基金项目(30670317和39970438);; 厦门大学新世纪优秀人才支持计划项目(0000-X07115)资

ETF期现套利的可操作性分析

沪深300股指期货的推出,使ETf的期现套利操作具有实践的可能。通过最小二乘法可以确认深证100ETf与上证180ETf的组合作为拟合沪深300指数的现货变量。套利成本为交易成本和跟踪误差。当股指期货的价格与ETf组合构成的现货价格之差大于套利成本时就可以进行套利操作。用当前的日数据进行实证分析表明,套利空间并不存在。原因可能与套利成本过高,以及市场存在众多套利者使得瞬间出现的套利机会立刻被发现、价格的短暂偏离得到迅速纠正有关。The arbitrage trade between exchanges traded fund(ETF)and the stock index future is available with the introduction of Hushen 300Index Futures.The paper uses OLS to regress the different portfolios of ETF and chooses Shenzhen 100ETF and Shanghai 180ETF.The arbitrage costs include tracing error of the portfolios and the cost of trading.Then it gets the non-arbitrage space through the price minus the costs.The Empirical analysis of daily data reveals that the arbitrage chance doesn 't exist for the high arbitrage costs.Another reason lies in that there are a lot of arbitragers in the investing market and the departure of the price could be corrected immediately

Effects of Carbon Supports on Electrocatalytic Activities of CoSe_2 Catalysts Toward Oxygen Reduction Reaction

选择了4种商用碳载体材料,即多壁碳纳米管(CnTS)、2种导电碳黑(bP2000和XC-72r)及石墨烯(gP),采用微波法分别制备了不同碳载体负载钴硒催化剂,考察了碳载体种类及柠檬酸预处理对钴硒催化剂晶体结构、表面形貌、催化剂中钴载量和酸性介质中氧还原反应(Orr)活性的影响.结果表明,未经柠檬酸处理的COSE2/bP2000和COSE2/XC-72r中钴载量分别达到15.6%和21.7%(质量分数,下同),比COSE2/CnTS(11.8%)和COSE2/gP(13.0%)中的钴载量要高,且较多的COSE2纳米颗粒能较好地分散并负载在XC-72r上,因此其氧还原催化活性较好,峰电位和Orr电位分别为285和410MV(VS.饱和甘汞电极(SCE)),转移电子数约为4.经柠檬酸处理后制备得到的不同碳载体负载钴硒催化剂的晶体结构、钴载量和氧还原活性没有明显改变,但降低了载体的石墨化程度,加剧了COSE2纳米颗粒在碳纳米管上的团聚.In this work,four types of commercial carbon support materials,namely,multiwall carbon nanotubes(CNTs),Black Pearls 2000(BP2000)carbon black,Vulcan XC-72 Rcarbon black,and grapheme(GP),were used separately to prepare different carbon supported cobalt selenide(CoSe2/C)catalysts.The effects of carbon support type and pretreatment with citric acid on crystal structure,Co load and electrocatalytic activity toward oxygen reduction reaction(ORR)of the catalysts in an acidic medium were preliminarily examined.Without citric acid pretreatment,the Co loads in CoSe2/BP2000 and CoSe2/XC-72 Rreached 15.6%(by mass)and 21.7%(by mass),respectively,higher than those in CoSe2/CNTs(11.8%,by mass)and CoSe2/GP(13.0%,by mass).The highest Co load in CoSe2/XC-72 Rled to its best ORR activity.The peak potential and ORR potential of CoSe2/XC-72 Rwere 285mV and 410mV(vs.SCE),respectively,and the electron transfer number was about 4in sulfuric acid solution.However,the crystal structure,Co load,and ORR activity of CoSe2/C catalysts were not obviously affected by citric acid pretreatments of carbon supports.国家自然科学基金(11372263