橡胶树未成苗体细胞胚的茎芽分化及利用

以橡胶树未成苗体细胞胚为试材,选取未成苗双子叶胚、连体胚、多子叶胚、单子叶胚和子叶愈伤化胚作为外植体,研究不同体细胞胚类型的外植体分化茎芽的情况,并利用其进行幼态微型芽条的培育研究。结果表明:在植株诱导培养基中培养80d后,未成苗双子叶胚、连体胚、多子叶胚、单子叶胚、子叶愈伤化胚均能分化出芽,双子叶胚分化率最高(达90%),单子叶胚最低(20%),多子叶胚和连体胚最多可分化出芽3个,双子叶胚2个。幼态微型芽条增殖的最优培养基为MS+6-BA2mg·L-1或MS+6-BA2mg·L-1+KT1mg·L-1,而添加NAA对芽的伸长有抑制作用;适宜幼态微型芽条伸长培养的基本培养基为MS。     

Physiological dormancy in seeds of two endemic species of Begonia from Yunnan Province,China: diagnosis and classification

With the purpose of assessing the status of dormancy in seeds of two Begonia species (Begonia lithophila and Begonia guishanensis), freshly matured seeds were given gibberellic acid and moist chilling and allowed to dry after ripening. The seeds were then germinated on media with or without KNO₃ at 15, 20, 25, 30 and 18/25°C. All three treatments significantly increased germination percentages. Examination by X‐ray revealed that seeds of both species have a fully developed embryo and thus have no morphological component of dormancy; seeds readily imbibed water and KNO₃ solution. Therefore, we conclude that seeds of the two Begonia species have non‐deep physiological dormancy. Although KNO₃ significantly increased germination in both species, alternating temperatures did not, suggesting that the most favorable microhabitat for germination is small‐scale disturbances under the forest canopy.     

石竹属植物叶表皮特征及其系统学意义

用光学显微镜和扫描电镜,对石竹属12个种的植物叶表皮特征进行观察,统计并测量叶表皮气孔大小、气孔密度及气孔指数。结果表明,石竹属植物叶表皮细胞形态(表面观)为长方形和不规则多边形。乳突只存在于针叶石竹、高石竹和细茎石竹中。按气孔形状可将其分为了3个类型:椭圆形、卵圆形和长方形。研究结果对石竹属的系统分类和种间亲缘关系研究具有一定的参考价值。     

根瘤菌菌剂的研究与开发现状

根瘤菌与豆科植物共生成为豆科植物固氮的重要方式,它可以为豆科植物提供所需氮量的1/2～1/3。因此,土壤中有效根瘤菌的数量是决定豆科植物产量的重要因素,而根瘤菌菌剂的使用可以有效地提高土壤中根瘤菌数量。本文从根瘤菌菌剂制备中高效菌种的选育及匹配、高密度菌剂的制备、菌剂保存方法等方面进行综述。比较了自然选育、杂交选育和诱变选育等各类选育方法及琼脂试管配对法和水培配对法的优缺点;总结了菌剂制备的一般过程和方法;论述了菌剂保藏过程中冷冻干燥法和各种保护剂的使用对菌剂保藏效果的影响。本文阐述了根瘤菌菌剂的制备工艺和发展方向,为根瘤菌剂的研制提供重要参考。     

昆明地区15种常见木本植物活枝的燃烧性

为分析比较不同植物活枝的燃烧性,在森林防火戒严期内,对昆明地区15种常见木本植物中小径级的活枝进行了热辐射引燃试验,对小径级的活枝进行了氧指数试验。在测定样品直径、含水率、引燃时间、有焰燃烧时间、试验过程中烟气温度和质量损失变化过程等基础上,提出并计算了表征活枝燃烧性能的综合燃烧特性参数S,根据该参数对15种植物中小径级活枝的燃烧性能进行了排序。结果表明,15种植物小径级的活枝均具有较强的阻燃性,燃烧性能顺序为:云南松<野八角<华山松<滇青冈<地盘松<云南樟<厚皮香<大白花杜鹃<炮状花杜鹃<云南含笑<小白花杜鹃<南烛<光叶石栎<元江栲<云南野山茶。根据氧指数及试验现象将15种植物的小径级活枝分为3类,其中难燃类4种(大白花杜鹃、野八角、厚皮香、南烛)、可燃类7种(云南含笑、云南松、地盘松、华山松、滇青冈、云南樟、云南野山茶)、较易燃类4种(小白花杜鹃、炮状花杜鹃、光叶石栎、元江栲)。分析了造成2种试验结果差异的主要原因。     

利用B细胞培养和RT-PCR技术从我国HIV-1感染者中筛选膜蛋白特异性单克隆抗体的初步研究

本研究通过采集1型人类免疫缺陷病毒(Human immunodeficiency virus-1,HIV-1)感染者抗凝全血,分离出外周血单个核细胞,然后用磁珠分选纯化记忆性B细胞和体外活化记忆性B细胞,促使其分泌抗体,用ELISA法识别阳性B细胞克隆,并提取阳性B细胞的RNA,从中扩增抗体重链和轻链基因并克隆到表达载体中,再用携带重链基因的质粒和携带轻链基因的质粒共转染293T细胞,获得HIV-1特异性人单克隆抗体,进行抗体特性的鉴定。结果从1例HIV-1感染者的记忆性B细胞中筛选出了4株HIV-1包膜糖蛋白(Envelope glycoprotein,Env)特异性人单克隆抗体,其中2株具有较好的抗体依赖细胞介导的细胞毒作用活性,另有1株对HIV-1假病毒有较弱的中和活性。说明我们成功地引进了利用B细胞培养和RT-PCR技术从人体淋巴细胞中筛选特异性抗体基因的人单克隆抗体技术平台。用该技术可以成功获得HIV-1Env特异性单克隆抗体,为将来从能产生高滴度广谱中和抗体的感染者体内筛选广谱中和抗体打下了基础。     

Local and global effects of Mg2+ on Ago and miRNA-target interactions

Three magnesium ions (Mg(2+)), named Mg1 (in Mid domain), Mg2 and Mg3 (both in PIWI domain), located at the small RNA binding domain of Argonaute (Ago) protein, are important for sequence-specific miRNA-target interactions. Such conjunction between the Ago protein and miRNA raises the question: How do Mg(2+) ions participate in the recognition process of miRNA by Ago or its target. Furthermore, it is still unclear whether the Mg(2+) ions contribute to the local or global stability of the miRNA complex. In this work, we have performed a series of 16 independent molecular dynamic simulations (MD) to characterize the functions of Mg(2+), hydration patterns and the conformational events involved in the miRNA-target interactions. The cross correlation analysis shows that Mg1 and Mg2 significantly enhance a locally cooperated movement of the PAZ, PIWI and Mid domains with the average correlation coefficient of ～0.65, producing an "open-closed" motion (rotation Angle, 46.5°) between the PAZ and PIWI domains. Binding of Mg3 can globally stabilize the whole Ago protein with the average RMSD of ～0.34 ?, compared with the systems in absence of Mg3 (average RMSD?=?～0.43 ?). Three structural water molecules surrounding the Mg(2+)-binding regions also stabilize these ions, thus facilitating the recognition of miRNA to its target. In addition, the thermodynamic analysis also verifies the positive contribution of all three Mg(2+) to the binding of miRNA to Ago, as well as the importance Mg2 plays in the cleavage of the miRNA targets.     

过表达AtchyB基因提高洋桔梗光胁迫耐受性的研究

类胡萝卜素尤其是叶黄素循环类物质在植物抵抗由强光照引起的非生物胁迫中发挥着重要的作用,为了提高洋桔梗对强光照的抗性,从拟南芥中克隆了类胡萝卜素生物合成途径中参与叶黄素循环关键酶——β-胡萝卜素羟化酶基因(AtchyB),利用农杆菌介导法将其转入洋桔梗中,最终得到遗传转化植株2个株系,研究发现,转基因植株中总类胡萝卜素含量高于对照组,且叶黄素循环池被不同程度地放大。在不同光照强度下,转基因洋桔梗植株对光照耐受性明显强于对照组,且转基因植株生物量也明显提高。表明过表达AtchyB基因使洋桔梗光胁迫耐受性有所增强。     

响应面法优化低温豆粕大豆分离蛋白提取工艺

采用响应面分析法(RSM)对低温豆粕大豆分离蛋白(soybean protein isolated,SPI)的碱提工艺进行优化。在单因素实验的基础上,选取了影响SPI提取率的4个关键因素(pH、温度、时间和液料比)进行四因素五水平的中心组合旋转实验设计(CCRD)。通过RSM建立了响应值(SPI提取率)与各影响因素之间的回归方程,并获得了SPI的最优提取条件:pH 8.5,提取温度55℃,提取时间42.8 min,料水比1∶9.7(g/mL),此条件下SPI提取率预测值为37.12%,与实验值(36.69%)的误差为1.16%。将一次碱提后残渣进行二次碱提,二次提取率为10.16%。2次碱提上清液等电点沉淀的蛋白沉淀率分别为84.03%和85.84%。