两种光呼吸抑制剂对草莓若干生理指标及产量品质的影响

以"丰香"草莓为试材,在花期喷施不同浓度的光呼吸抑制剂NaHSO₃和异烟肼。结果表明,喷施一定浓度的NaHSO₃(100 mg/L)和异烟肼(0.5 mg/ml),可增加草莓植株叶面积、叶绿素总量和光合速率;同时可提高坐果率,增加单果重和产量,果实总糖、可溶性固形物含量也显著提高。     

Noggin and bFGF cooperate to maintain the pluripotency of human embryonic stem cells in the absence of feeder layers

Human embryonic stem (hES) cells are typically maintained on mouse embryonic fibroblast (MEF) feeders or with MEF-conditioned medium. However, these xenosupport systems greatly limit the therapeutic applications of hES cells because of the risk of cross-transfer of animal pathogens. Here we showed that the bone morphogenetic protein antagonist noggin is critical in preventing differentiation of hES cells in culture. Furthermore, we found that the combination of noggin and basic fibroblast growth factor (bFGF) was sufficient to maintain the prolonged growth of hES cells while retaining all hES cell features. Since both noggin and bFGF are expressed in MEF, our findings suggest that they may be important factors secreted by MEF for maintaining undifferentiated pluripotent hES cells. Our data provide new insight into the mechanism how hES cell self-renewal is regulated. The newly developed feeder-free culture system will provide a more reliable alternative for future therapeutic applications of hES cells.     

蜘蛛杀虫肽基因的合成及其在植物中表达质粒的构建

近年来用生物制剂防治害虫,虽然可以避免环境污染,但效果往往不稳定,而用基因工程方法,将抗虫基因导入植物的基因组中,让植物自身产生抗虫物质,将是一种理想的途径［１,２］。抗虫的植物基因工程主要是利用苏云金杆菌的内毒素蛋白,转化此基因的烟草和番茄显示了对虫的抗性［３—６］。澳大利亚Ｄｅａｋｉｎ大学从一种蜘蛛毒液中分离纯化到一种只有３７个氨基酸的小肽,体外实验发现其能杀死多种对农业生产有害的昆虫,但对哺乳动物没有毒害作用［７］。我们根据此肽的氨基酸序列,采用植物偏爱的密码子,人工合成并克隆了此肽的基因…     

Fast classification and compositional analysis of cornstover fractions using Fourier transform near-infrared techniques

The objectives of this research were to determine the variation of chemical composition across botanical fractions of cornstover, and to probe the potential of Fourier transform near-infrared (FT-NIR) techniques in qualitatively classifying separated cornstover fractions and in quantitatively analyzing chemical compositions of cornstover by developing calibration models to predict chemical compositions of cornstover based on FT-NIR spectra. Large variations of cornstover chemical composition for wide calibration ranges, which is required by a reliable calibration model, were achieved by manually separating the cornstover samples into six botanical fractions, and their chemical compositions were determined by conventional wet chemical analyses, which proved that chemical composition varies significantly among different botanical fractions of cornstover. Different botanic fractions, having total saccharide content in descending order, are husk, sheath, pith, rind, leaf, and node. Based on FT-NIR spectra acquired on the biomass, classification by Soft Independent Modeling of Class Analogy (SIMCA) was employed to conduct qualitative classification of cornstover fractions, and partial least square (PLS) regression was used for quantitative chemical composition analysis. SIMCA was successfully demonstrated in classifying botanical fractions of cornstover. The developed PLS model yielded root mean square error of prediction (RMSEP %w/w) of 0.92, 1.03, 0.17, 0.27, 0.21, 1.12, and 0.57 for glucan, xylan, galactan, arabinan, mannan, lignin, and ash, respectively. The results showed the potential of FT-NIR techniques in combination with multivariate analysis to be utilized by biomass feedstock suppliers, bioethanol manufacturers, and bio-power producers in order to better manage bioenergy feedstocks and enhance bioconversion.     

植物萜类代谢工程

植物萜类化合物不仅在植物生命活动中起重要作用,而且具有重要商业价值。随着近年来萜类代谢途径和调控机理研究的深入,代谢工程已成为提高萜类产量最有潜力的途径之一。对萜类代谢工程领域具代表性的研究结果进行了全面回顾,然后讨论了萜类代谢工程的研究方法和策略,其中重点探讨了功能基因组学方法在萜类代谢途径及调控机理研究方面的应用。     

海洋氮循环中细菌的厌氧氨氧化

细菌厌氧氨氧化过程是在一类特殊细菌的厌氧氨氧化体内完成的以氨作为电子供体硝酸盐作为电子受体的一种新型脱氮反应.厌氧氨氧化菌的发现,改变人们对传统氮的生物地球化学循环的认识:反硝化细菌并不是大气中氮气产生的唯一生物类群.而且越来越多的证据表明,细菌厌氧氨氧化与全球的氮物质循环密切相关,估计海洋细菌的厌氧氨氧化过程占到全球海洋氮气产生的一半左右.由于氮与碳的循环密切相关,因此可以推测,细菌的厌氧氨氧化会影响大气中的二氧化碳浓度,从而对全球气候变化产生重要影响.另外,由于细菌厌氧氨氧化菌实现了氨氮的短程转化,缩短了氮素的转化过程,因此为开发更节约能源、更符合可持续发展要求的废水脱氮新技术提供了生物学基础.     

Linking seasonal inorganic nitrogen shift to the dynamics of microbial communities in the Chesapeake Bay

Seasonal shifts of dissolved inorganic nitrogen (DIN) and the dynamics of microbial communities for nitrogen transformation were investigated in the water column of Chesapeake Bay. The relative abundance of nitrogen over phosphorus (N*) showed a strong seasonal and spatial pattern: gradually decreased from upstream to downstream; high in winter and low in summer. Because the phosphorus concentration remained relatively stable, the spatiotemporal pattern of N* implied that a substantial fraction of DIN was removed in the bay, especially in summer. Correlation analyses indicated the functional microbial communities and environmental variables, such as temperature, dissolved oxygen, salinity, played important roles for connecting the seasonal variation of N*. Among them, temperature was the trigger factor. High temperature in the summer induced the growth of functional microbes, which subsequently consumed a large portion of DIN inputted from the tributaries and reduced the N*. The current study provided the relative importance of microbial communities and environmental variables in driving the DIN loss in the bay.     

植物激素对草莓叶片不定芽形成的影响

用试管内生长的草莓幼嫩叶片作外植体,培养在MS基本培养基上附加1.5—2.5毫克/升6—BA和0.1毫克/升NAA,可直接诱导成不定芽,诱导率可达20%。如果不定芽继代培养在同样浓度的培养基上,继而可形成大量的丛生芽。能使叶外植体形成不定芽的植物激素组合而不能使其愈伤组织分化成芽。IAA与6—BA的不同浓度组合对不定芽形成效果不明显。     

鸡传染性喉气管炎病毒gB基因的克隆及其在耻垢分枝杆菌中的表达

以ILTV基因组为模板 ,利用PCR特异扩增出gB基因 ,定向克隆到中间质粒载体pY_α ,构建了中间质粒pY_α_gB。然后以中间质粒pY_α_gB为模板 ,扩增出含有人结核分枝杆菌启动子hsp70基因和堪萨斯分枝杆菌α信号肽基因的hsp_α_gB片段 ,回收补平后与穿梭表达载体pRR3平端连接 ,从而构建大肠杆菌_分枝杆菌穿梭表达质粒pR_α_gB。再将其电转化至耻垢分枝杆菌M .smegmatismc2 15 5 ,ELISA检测表明重组菌株M .smegmatismc2 15 5 (pR_α_gB)的表达产物具有很好的反应原性。Westernblot检测说明gB基因在分枝杆菌中获得了表达并具有良好的免疫原性。鸡胚中和试验结果表明该重组菌株可以中和 1个剂量EID50 的ILTV强毒 ,能够保护SPF鸡胚抵抗强毒攻击