Determination of copy number for 5S rDNA and centromeric sequence RCS2 in rice by Fiber-FISH

The copy number of 5S rDNA and centromeric sequence RCS2 was determined by extended DNA fiber based fluorescence in situ hybridization (Fiber-FISH) in rice (Oryza sativa ssp. indica cv. Guangluai No. 4) genome. In order to determine the copy number, it is necessary to know the basepair number that a given length DNA fiber contains under a microscope. Therefore, the length of two DNA fragments, in which the basepair number had been already known, was measured. The insert sequence of the tested BAC 38D17 was 136 kb and its extended DNA was 56.4 μm long, 2.41 kb/μm on average, while that of the tested BAC 44B4 was 144.5 kb in total and 55.7 μm long, 2.60 kb/μm on average under the microscope. They were very close to the theoretical value of B-DNA in the Watson-Crick DNA model, which is 2.97 kb/μm. According to the average value of basepair number per μm of the two samples mentioned above, that is, 2.51 kb/μm, it could be estimated that the copy number was about 686 for 5S rDNA and 286-1121 for the centromere sequence RCS2.     

Using specific secondary metabolites as markers to evaluate allelopathic potentials of rice varieties and individual plants

It is a key of the breeding of allelopathic rice cultivars to evaluate and screen few accessions with allelopathic traits from numerous rice accessions and individual plants. Rice varieties and individual plants with allelopathic traits demonstrated their allelopathic effects by producing and releasing specific secondary metabolites into environment. Therefore, using specific secondary metabolites as markers, the allelopathic potentials of rice varieties and individual plants could be evaluated by HPLC. The allelopathic potentials of 3000 rice accessions and some individual plants of F3 and F4 were evaluated by this method in 1 a. If these accessions and plants were evaluated by the traditional method in the field, it would take more than 10 a, furthermore, the breeding process of allelopathic rice cultivars would be directed and monitored by this method. Isolation and structural identification of specific secondary metabolites was done by LC/MS coupling ¹H and ¹³C NMR. It revealed that allelochemicals of rice tissue were glucosides of resorcinol, flavone and hydroxamic acid, and were not well-known phenolic and fatty acids in previous studies. However, these glucosides could degrade immediately into sugar, phenolic and fatty acids under microbial and acidic medium when they released into the environment.     

水稻小GTP蛋白OsRab5A的表达、纯化和GTP结合分析

小GTP结合蛋白是一类在细胞内的运输过程中重要作用的蛋白。它们通过结合子GTP而激活 ,当GTP被水解为GDP后处于非活性状态。哺乳动物中的研究表明 ,Rab5A蛋白是细胞内的形成早期内吞体 (earlyendosome)的限速因子。证实了所克隆的水稻rab5A基因编码的蛋白具有GTP结合功能。将Osrab5A基因的编码序列按正确读码框重组到pGEX4T1载体中 ,转化大肠杆菌BL2 1(DE3) ,电泳判定插入片段大小无误后 ,进一步测序鉴定其读码也无误。将该克隆命名为pG_5AE。以IPTG诱导 pG_5AE所编码的融合蛋白GST_OsRab5A的表达。SDS_PAGE电泳与无外源质粒和表达谷胱甘肽硫转移酶 (GST)的对照相比 ,得到了预计大小的融合蛋白。以GSTrapTM亲和柱纯化融合蛋白。在不同的泳道分离纯化的融合蛋白和作为对照的含GST以及无外源蛋白的细菌总蛋白 ,电转移到硝酸纤维膜上。将该膜与α_3 2 PGTP温育 ,洗膜 ,放射自显影后 ,获得了融合蛋白结合GTP的结果 ,这表明在原核中表达出的水稻Rab5A蛋白能在体外结合GTP。     

黑米色素稳定性的研究

黑米中含有丰富的天然红色素，研究了常用食品添加剂，糖类和常见金属离子：Na^ 、K^ 、Ca^2 、Fe^2 、Zn^2 、Al^3 对黑米色素稳定性的影响。并对色素的耐碱性，耐氧化性，耐还原性，耐光耐热性进行了探讨。     

氮水平对水稻光合特性的影响

用缺氮(ON)、低氮(LN)、中氮(MN)、高氮(HN)、超高氮(SN)盆栽土培的杂交水稻汕优64和金南风为材料,测定植株和叶片的生长状况、叶片总N含量、光合速率、光呼吸速率、气孔导度和叶肉导度的变化.结果表明:供试两品种随着施N量的增加,植株的分蘖数增多,株高增加,气孔密度减少, 叶片总N含量、叶绿素含量、光呼吸速率、叶肉导度等均增加.供试两品种的净光合速率变化存在差异,金南风叶片的净光合速率是随着施N量的增加而增加,但汕优64在HN和SN的条件下净光合速率反而下降,说明在HN和SN的水平上光合碳代谢的途径发生了变化,即光氧化环增加的幅度大于光合还原环.     

稻麦草氨法制浆工艺研究

研究了在氨水中添加少量钾碱作为蒸煮剂的稳麦草制浆新工艺，讨论了蒸煮剂的用量和配比，液固比，蒸煮最高温度，升温时间和保温时间对蒸煮效果的影响，继而确定了适宜的工艺条件，结果表明，该蒸煮体系对稻，麦草木素的脱除率达到85%。纸浆得率为稻草38.12%(细浆得率）和麦草49.65%(粗浆得率）。通过红外光谱（IR）测定了稻草蒸煮过程中木质素的结构变化。     

毛细管气相色谱分析杂交水稻亲本幼苗中的脂肪酸

报导了杂交水稻亲本幼苗中脂肪酸测定的毛细管气相色谱分析法，研究了样品中脂肪酸的提取。用色－质联用仪对已分离脂肪酸进行了定性。分离效果好，定量的准确度高，方法的相对标准偏差小于１．５％。     

机器视觉测量大米留胚率的研究

利用计算机视觉系统，研究大米胚芽的自动识别方法,在分析大米的表面积及轮廓线的二次微分曲线基础上，提出利用大米微分模型识别群体胚芽米的留胚率的设想．     

水稻丰收菌(Bacillus cereus R_2)对水稻幼苗的生理效应初探

用水稻丰收菌悬浮液处理种子或种芽后，有增加苗高、苗地上部鲜重、根鲜重、根干重的促生长作用；过氧化氨酶活性也高于清水对照，并有随菌量提高酶活性递增的趋势；叶绿素含量高8．7％～13％；根系对32争的吸收比对照高35．8％～83．9％；菌剂中加防腐剂苯甲酸钠对稻苗无不良影响.复壮菌株校未复壮者其生理效应有所提高．