发根农杆菌介导的菠菜毛状根遗传转化体系的建立

发根农杆菌(Agrobacterium rhizogenes)侵染植物后可诱导植物产生毛状根。菠菜(Spinacia oleracea)是常见的食用蔬菜, 目前尚未见菠菜毛状根的研究报道。经筛选得到适合诱导菠菜毛状根的发根农杆菌菌株LBA9402, LBA9402侵染菠菜外植体茎后, 毛状根的诱导率最高可达16%。菠菜毛状根呈白色, 具有丰富的根毛, 能在无外源激素的固体培养基上快速增殖生长。通过诱导菠菜毛状根产生愈伤组织并进行分化, 获得了菠菜毛状根的再生植株, 再生率为8%。此外, LBA9402可将含有Ri质粒的T-DNA和携带外源GFP基因的Ti质粒T-DNA共同导入外植体中。PCR检测和荧光显微观察结果显示, rolB及GFP基因在菠菜毛状根基因组中稳定表达, 共转化频率为50%。     

拟南芥IAA酰胺合成酶GH3-6负调控干旱和盐胁迫的反应

生长素是一种重要的植物激素, 几乎参与了植物所有的生命活动过程。GH3-6具有IAA酰胺合成酶活性, 催化氨基酸与IAA形成IAA的氨基轭合物, 发挥暂时或永久灭活IAA的作用。该文探讨了GH3-6基因在拟南芥(Arabidopsis thaliana)逆境适应过程中的功能。结果显示GH3-6基因受干旱、ABA和高盐的诱导表达。与野生型相比, GH3-6基因过表达突变体dfl1-D对干旱的抗性明显减弱, 叶片失水速率更快。在抗盐方面, dfl1-D也显著弱于野生型。在3种逆境(干旱、ABA和高盐)胁迫下, GH3-6基因的高表达抑制了逆境响应基因RD22、KIN1、RD29A和DREB1A的表达。而且在干旱胁迫下, dfl1-D中ABA的含量明显低于野生型。研究结果证明, 高表达GH3-6基因负调控拟南芥对逆境的抗性。     

利用叶绿素荧光评估草原植物羊草缺磷缺氮状况

羊草(Leymus chinensis)是北方草原的重要牧草。准确评估其营养状况,对维护羊草草原的生产力具有重要意义。以羊草幼苗为材料,利用能同时表征2个光系统光化学活性的叶绿素荧光检测技术,对缺氮和缺磷处理下的叶片光化学活性进行分析。结果表明,缺氮处理20天后羊草叶片叶绿素含量降低近50%。同期缺磷及缺氮处理对PSⅡ功能的影响总体大于PSⅠ。与对照相比,缺氮叶片的Φ(Ⅱ)和Φ(Ⅰ)分别比对照降低了30.3%与38.5%;ETR(Ⅱ)与ETR(Ⅰ)分别降低30.8%和28.9%。缺磷处理组Φ(Ⅱ)和ETR(Ⅱ)的降低幅度约为缺氮的1/2。这些定量研究结果对及时有效地诊断和区分羊草植物氮磷缺乏状况具有重要的参考价值。     

基于孢子形态和分子证据探讨鳞盖蕨属(碗蕨科)系统分类

孢粉学是解决植物分类中疑难类群物种微形态分化的重要方法, 随着分子系统学的发展, 结合这两门学科的优势可以更加有效地解决疑难类群的分类学问题。鳞盖蕨属(Microlepia)是一个分类困难的疑难类群, 采用孢粉学与分子系统学一一对应的方法, 以及居群取样方式, 选取280份样本, 联合4个叶绿体片段(rbcL、trnL-F、psbA-trnH和rps4), 采用最大似然法和贝叶斯法构建该属的系统发生关系, 在此基础上对凭证标本中100份材料的孢子进行观察和分析。综合分子系统学和孢粉学的研究结果, 得出结论: (1) 在形态学研究中广泛被接受的15个物种得到了单系支持, 并厘清了分类困难的复合群; (2) 发现边缘鳞盖蕨(M. marginata)可能存在隐性种; (3) 建议恢复过去归并处理为异名的瑶山鳞盖蕨(M. yaoshanica)、罗浮鳞盖蕨(M. lofoushanensis)、四川鳞盖蕨(M. szechuanica)以及滇西鳞盖蕨(M. subspeluncae); (4) 提出鳞盖蕨属可能存在杂交现象; (5) 提出鳞盖蕨属完整的属下分类建议。     

Comparison of two management strategies for Helicobacter pylori treatment: clinical study and cost-effectiveness analysis

BACKGROUND: First-line proton pump inhibitor-based triple and quadruple therapies for Helicobacter pylori eradication present similar levels of efficacy. Cross-over treatment (quadruple following triple failure, and triple following quadruple failure) seems the most sensible approach to treatment failures, but the two strategies -'quadruple first' versus 'triple first'- have not been previously compared. The aims of our study were to assess the usefulness and the cost-effectiveness of the two treatment strategies. MATERIAL AND METHODS: Forty-nine out of 344 patients included in a previous study comparing triple therapy - 7 days of omeprazole, amoxicillin and clarithromycin twice a day - with quadruple therapy - 7 days of omeprazole twice a day, plus tetracycline, metronidazole and bismuth subcitrate three times a day - failed initial treatment and were assigned to cross-over therapy. Cure was determined by urea breath test. A decision analysis was performed to compare the two eradication strategies. RESULTS: Intention to treat cure rates were 46% (10/22 patients; 95% CI 24-68%) for second-line triple therapy and 63% (17/27 patients; 95% CI 42-81%) for second-line quadruple therapy. Per protocol cure rates were 71% and 85%, respectively. Intention to treat cure rates were 87% (95% CI 81-92%) for the 'triple first' versus 86% (95% CI 80-91%) for the 'quadruple first' strategy (p = .87). The 'quadruple first' strategy was more cost-effective. The incremental cost of 'triple first' strategy per person was 19 in the low-cost area and 65 US dollars in the high-cost area. CONCLUSIONS: The effectiveness of 'triple first' and 'quadruple first' strategies is similar, although the latter seems slightly more cost-effective.     

一种优化的测定水稻硅含量的方法

为建立一种更为简便且准确的水稻(Oryza sativa)硅含量测定方法, 对硅钼蓝分光光度法的多个实验条件进行了优化, 并对水稻样品的前处理——消解法和高压灭菌法进行了比较研究。结果表明, 还原剂为抗坏血酸、测定波长为600 nm、硅钼黄显色时间和硅钼蓝稳定时间分别为5和25分钟为最佳测定条件, 样品的前处理则是消解法优于高压灭菌法, 前者提取硅的效果好于后者。该优化方法为深入研究水稻和其它植物中硅的吸收和转运机制奠定了基础。     

海豹也需要尊重

每年春天．成千上万只琴海豹和帽海豹从北极迁游到加拿大东海岸,在圣劳伦斯湾清新纯净的浮冰上繁殖后代。那时,万里冰原变成了海豹的育婴园。雪白、毛绒绒的小海豹沐浴在初春的阳光下,依偎在妈妈的身旁吸吮乳汁。刚出生的小海豹不会游泳,为了抗拒严寒,它们必须大量地吃极富脂肪的奶水,以每天增长两公斤的速度成长。春末夏初,冰面融化,     

关于中国淡水生态系统生物多样性监测与管理的探讨

China is one of the countries in the world with therichest species biodiversityinfreshwater ecosystem.How-ever,duetothe rapid economic growthandthe continuingincrease of human disturbances and destructions of aquatichabitats,the biodiversity of freshwater ecosystemsis dras-tically declining.Waterbodies become more and more“deserted”of sensitive species.Water areas are reduced,fragmentized,and changed in their hydrodynamics(i.e.damming),causing changes in sedimentation and otherchanges.Forinstance,the area o...     

龙感湖沉积物泥芯硅藻群落和营养状态的反演

The importance of aquatic vegetation to the ecologi-cal restoration has been recognized commonly bylimnolo-gists and lake managements[1—4].As to the ecologicalrestoration in eutrophicated lakes,it is of great signifi-cance to knowthe dynamic process of the ecosystemevo-lution in a macrophyte-dominated lake under the humanimpacts in historical period,to make it clear whether thecommunitystructure and ecological function would be af-fected bythe extension of the vegetation growth,tofind asolutionto remain ste...     

植物生长调节物质在提高林木幼苗成活率方面的应用

目前,植苗造林是我国主要造林方式,造林用的苗木,大部分是裸根苗,苗圃中的幼苗,经过起苗、选苗、假植、包装、运输、移栽等环节,容易造成裸根苗的机械损伤,影响根系的生长和造林成活率。1978年以来,我们使用几种植物生长调节物质,对黑龙江省主要造林树种的幼苗,进行移栽前的根系处理,可以增强幼林的抗旱能力,提高造林成活率与幼林平均年高生长。