Copper‐Induced Oxidative Stress and Responses of the Antioxidant System in Roots of Medicago sativa

The effects of various copper (Cu) concentrations on the antioxidative system in the roots of Medicago sativa were explored. The results indicated that the Cu content of the roots reached a value of 854 μg g^?1 DW at 10 μm Cu and a value of 4415 μg g^?1 DW at 100 μm Cu, suggesting that M. sativa has better ability to tolerate and accumulate Cu than other Cu‐bioaccumulators, and is a potential plant for phytoremediation. Treatment with Cu resulted in a significant increment in the levels of H₂O₂, O₂˙^? and OH˙. The reduced form of ascorbate and glutathione reached a peak at 30 μm Cu, and was followed by a sharp depletion to a lower level than that of the control. In contrast, the levels of the oxidised forms of ascorbate and glutathione showed a progressive increment with increasing Cu concentrations, suggesting that the antioxidant system was unable to cope with Cu stress at higher Cu levels. Under the Cu concentrations tested, the activity of catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase (GR, EC 1.6.4.2) increased at lower Cu concentrations, and then decreased, reaching a maximum at 30 μm of Cu for APX and GR, at 10 μm for CAT, whereas the activities of guaiacol peroxidase (POD, EC 1.11.1.7) were gradually increased with increasing Cu concentrations. PAGE analysis of superoxide dismutase (SOD, EC 1.1.5.1.1) revealed that one band is a Mn‐SOD and five bands are identified as Cu, Zn‐SOD, whereas Fe‐SOD isoforms were not found in the roots of alfalfa. Cu at 10–100 μm increased the intensity of constitutive isozymes of CAT, APX and POD, whereas it decreased the intensity of isozymes of glucose‐6‐phosphate dehydrogenase (G6PDH, EC 1.1.1.49) significantly. The activities of lipoxygenases (LOX, EC 1.13.11.12) were gradually augmented with increasing Cu concentrations, demonstrating that LOXs are probably involved in production of lipid hydroperoxides and superoxide anion. There was a continuous and pronounced enhancement in the activity of esterase (EST, EC 3.1.1.1) in roots treated with 10–30 Cu μm , whereas EST activity in roots exposed to above 30 μm Cu declined, suggesting that EST plays a protective role under lower Cu concentrations stress.     

秸秆还田对中国农田土壤温室气体排放的影响

为了更好地了解和掌握秸秆还田对中国农田土壤温室气体排放的影响,笔者根据历年国内相关文献,就秸秆还田对中国农田土壤CO2、N2O和CH4等主要温室气体排放的影响进行较全面的综述。研究表明：秸秆还田能增加农田土壤CO2和CH4的排放通量,对N2O排放通量的影响表现为不确定性,分析了秸秆还田对农田土壤温室气体排放的影响因素,探讨了该领域存在的问题及未来的研究方向。秸秆还田对中国农田土壤温室气体排放有一定影响,对各温室气体影响程度和影响机理不同。     

大豆花粉管通道技术转化雪花莲凝集素(GNA)基因

采用花粉管通道技术,用雪花莲凝集素基因（Galanthus nivalis agglutinin,GNA）转化吉林省主推品种吉林20号、吉林30号、吉林45号品种大豆。通过接蚜鉴定和PCR鉴定,从所获得的种子苗中筛选出转基因植株。对转基因植株的后代进行分子生物学鉴定：（1）PCR分析,转基因植株97TGR1和97TGR2的T2代表现阳性,第5代表现阳性纯合;97TGR1、97TGR2和98FD1～98FD20的T3代Western blotting检测结果证明,GNA基因在蛋白质水平有表达,最高表达量占总可溶性蛋白的0．7％;97TGR1、98TGR2和99JI45 TGR2的Southern blotting检测结果显示,GNA基因已插入大豆基因组;（2）遗传学分析,97TRG1的T2代呈孟德尔3：1分离,97TGR2的T3代出现种皮颜色不规则分离。经过抗蚜性鉴定和连续的筛选,获得抗性纯系;（3）抗蚜性鉴定,转基因株的T1、T2世代转基因植株可抑制蚜虫繁殖量50％～90％;（4）品系鉴定,转基因大豆的抗蚜性达到农学标准抗（R）和高抗（HR）水平;大面积环境释放试验自然感蚜鉴定,转基因系蚜虫发生的高峰比对照延迟,高峰期过后群体蚜量的下降速度也比对照快。本研究认为,大豆花粉管通道技术可以利用于大豆的转基因研究和应用中,GNA基因在改良大豆的抗蚜性上是可取的。     

马蹄金ISSR反应体系的正交优化

以CTAB法提取的马蹄金叶片DNA为模板,应用L16(45)正交表系统分析了DNA、Mg2+、dNTP、Taq酶、引物5种ISSR反应成分浓度变化对扩增结果的影响。量化分析结果表明:Taq酶、dNTP不同水平对PCR反应结果有显著影响,正交设计可以应用于ISSR-PCR反应体系的建立,用这种方法建立的马蹄金IS-SR优化反应体系为:1×buffer,25ng模板DNA,1.75mmol/LMg2+,225μmol/LdNTP,0.9μmol/L引物,1.25UTaqDNA聚合酶,总体积20μl。这一优化系统的建立为今后利用ISSR标记技术,研究马蹄金的地理变异提供一个标准化程序。     

犬眠宝手术期间麻醉效果实验初报

通过监测犬眠宝合剂手术期间的镇痛、镇静、肌 松、呼吸、心率、体温及血氧饱和度及变化评价了犬眠宝的麻醉效果,结果表明犬眠宝在手术期间麻醉效果确实,对呼吸 循环系统影响较小,缺点是手术时体温下降幅度较大,所以应注意保温。     

小麦连体叶片高效瞬时表达体系的构建

分别以洋葱表皮和生长7d的小麦连体叶片为材料,采用HeliosTM基因枪将35S-sGFP-TYG-NOS (pUC19)外源基因导入植物细胞使其瞬时表达,摸索出一整套适合于小麦连体叶片高效瞬时表达体系的各项参数,包括：氦气压力、金粒子直径、PVP浓度、每次轰击的质粒DNA以及金粉用量等。并指出选用合适的质粒DNA浓度和多片小麦叶片同时轰击可有效提高转化效率。     

60Coγ射线种子辐射对大花高代 组培苗的生长及诱变效应

以0Gy、10Gy、50Gy、100Gy、150Gy和200Gy不同剂量的60Coγ射线辐射种子，研究其对大花高代组培苗生长影响的结果表明，在50~200Gy范围内，根和真叶的生长以及植株高度都不同程度地受到了抑制，且抑制程度与辐射剂量呈正相关，而10Gy则能促进根和真叶的生长。随着剂量的增高，死亡率增高，组培苗生长41d时的半致死剂量(LD50)为150Gy。各处理组培苗培养70d后，少量瓶内开花，出现花型、花色和花瓣变异。花型变异主要由对照的正常花形变为蝴蝶形。花色变异主要是颜色变浅，甚至变为白色。花瓣变异可由原来的单瓣变为重瓣花。以上结果表明，60Coγ射线辐射可以提高突变频率且诱变效应明显，有利于在大花高代育种中产生色彩丰富，花型、株型美观的变异类型     

Mutation Techniques for Gene Discovery and Crop Improvement

One of the most important breakthroughs in the history of genetics ）was the discovery that mutations can be artificially induced in organisms （van Harten, 1998）. Artificially induced mutations, by physical and chemical mutagens, have greatly advanced the understanding of genetics of higher organisms. Starting in the late 1960＇s, the International Atomic Energy Agency （IAEA） and the Food and Agriculture Organization （FAO） of the United Nations sponsored extensive research on mutation induction and their application to breeding of food and indnstrial crops that resulted in the introduction of new varieties of rice, wheat, barley, apples, citrus, sugar cane, banana, and others （more than 2 500 officially released new varieties are to be found in the FAO/IAEA Mutant Varieties Database） （hitp：//www-mvd.iaea.org/MVD/default.htm）. However, the usefulness of mutation techniques has been underappreciated in research communities, particularly during the last decade, when more and more researchers and breeders were rushing into molecular marker techniques and transgenic plants. In this paper, after a brief review of the past accomplishments of mutation induction and its application, we discuss the uniqueness of induced mutations in gene discovery and how to integrate induced mutants into functional genomics programs;     

Improving Drought Tolerance of Rice by Designed QTL Pyramiding

Drought is the most important factor limiting rice yields in the rainfed areas of Asia. To overcome the problem, we developed a new strategy ＇designed QTL pyramiding＇ to more efficiently develop drought tolerant （DT） rice cultivars. In the first phase of this strategy, we developed large numbers of introgression lines （ILs） in elite backgrounds using backcross （BC） breeding, each of which carries multiple genomic segments for improved DT from a known donor. Then, we genotyped all ILs with SSR markers to track the genomewide pattern of introgression in the DT ILs of 16 BC populations derived from crosses between 2 recipients （IR64 and Teqing） and four different donors. X^2 tests and linkage disequilibrium analyses of introgression in the DT ILs revealed significant frequency shifts at many loci across the genome and non-random associations at the multilocus level as a result of selection for DT in the ILs, which led us to the discovery of putative genetic networks underlying DT in the ILs. The networks each containing all DT loci detected in ILs from a BC population showed some interesting features.     

荞麦种子蛋白质组分分析

研究了不同品种荞麦种子中蛋白质组分情况，结果表明：养麦种子蛋白质主要由清蛋白、球蛋白、谷蛋白和醇溶蛋白构成。而不同类型蛋白质在总蛋白质中所占比例有明显差异，清蛋白是荞麦种子中的主要蛋白质，占总蛋白质含量的71．4％左右，其中以平荞最高。醇溶蛋白在荞麦种子总蛋白中所占比例较小，平均约为7．4％，榆养2号最高。球蛋白和谷蛋白所占比例非常接近，其中球蛋白平均约占9．1％，最高为日本大粒养。谷蛋白大约占总蛋白的12．1％，以京养1号最高。