大孔吸附树脂分离虎杖中白藜芦醇的研究

目的:采用大孔吸附树脂对虎杖粗提物中白藜芦醇进行初步富集、分离和纯化.方法:考察18种树脂对白藜芦醇的吸附量和解吸率,选择吸附量大、解吸率高的数种树脂进行吸附动力学研究,确定最佳的脱附工艺.结论:HPD-500树脂对白藜芦醇的吸附量可达58.67mg/g,解吸率为92.6%,经大孔吸附树脂的吸附与解吸,白藜芦醇的含量由粗提物中9.25%提高至39.5%.     

外殖体与不同理化因子对虎杖愈伤组织诱导及次生代谢产物形成的影响

考察了外植体、培养基及光照条件对中药植物虎杖愈伤组织形成及次生代谢产物生产的影响。总的来看, 所有愈伤组织中总酚和总黄酮含量比原植物的含量高2～3 倍; 而蒽醌的含量比原植物中含量低。外植体对愈伤组织形成及次生代谢产物生产的影响很大, 所考察的3 种外植体中, 叶外植的愈伤组织诱导率最高而源于根外植体的愈伤组织具有最好的次生代谢能力。所考察的6 种培养基中, MS + 0.5 mg/L 2 , 4 -D + 1.0mg/L 6-BA 和N6 + 0.5 mg/L 2 ,4 -D + 1.0 mg/L 6-BA 无论对于愈伤组织的产生还是次生代谢产物的累积都有较优表现。光照对愈伤组织诱导及次生代谢产物产生有明显影响, 但二者无规律性联系。     

西伯利亚蓼非特异性脂质转移蛋白编码序列的克隆及其盐胁迫下的表达

根据西伯利亚蓼地下茎抑制消减文库(SSH)中获得的非特异性脂质转移蛋白(non-specific lipid transfer protein, nsLTP)EST序列,应用RACE技术克隆了具有Poly A的全长cDNA序列.该序列全长604 bp,其5′非翻译区65 bp,3′非翻译区227 bp,开放阅读框编码103个氨基酸残基;序列分析表明,该基因具有N端信号肽,具有nsLTP家族共有的典型保守区域,属nsLTP家族基因,命名为PsnsLTPs;荧光定量PCR分析表明,PsnsLTPs在西伯利亚蓼叶、茎、地下茎中均有表达.在3%NaHCO3诱导表达下,该基因在地下茎中表达明显受盐胁迫的诱导,推测该基因在抵御盐胁迫时具有重要作用.     

何首乌苷通过激活BDNF/TrkB信号通路拮抗H2O2诱导的大鼠海马神经元氧化损伤

探讨脑源性神经营养因子/酪氨酸激酶受体B(BDNF/TrkB)信号通路激活参与何首乌苷(PMG)对过氧化氢(H2O2)诱导神经元氧化应激损伤的保护作用。实验采用神经元原代培养,建立大鼠乳鼠海马神经元氧化应激损伤模型。实验结果显示高浓度的H2O2与MTT测定的细胞存活率降低相关,选择细胞存活率在40%~50%之间的200μmol/LH2O2浓度作为氧化应激损伤的实验浓度。与模型组相比,PMG预处理组(200μmol/L)可抑制H2O2诱导的神经元损伤(P<0.001)。TUNEL和β-微管蛋白III荧光染色显示PMG保护H2O2诱导的神经细胞损伤,明显降低细胞凋亡率(P<0.001),细胞骨架形态恢复正常。与PMG+H2O2预处理组相比较,当加入BDNF/TrkB信号转导通路阻断剂K252a后,PMG+H2O2+K252a组神经元细胞存活率大幅度下降(P<0.01),细胞骨架形态呈损伤状态。同时,我们发现PMG预处理恢复H2O2诱导的BDNF和P-TrkB的低表达水平,并且用K252a阻断BDNF/TrkB信号传导抑制了PMG对BDNF和P-TrkB表达水平的影响(P<0.01)。综上所述,何首乌苷可能通过激活BDNF/TrkB信号转导通路及维护神经元骨架的完整,实现对大鼠海马神经元氧化应激损伤的拮抗作用。     

Heterophylly results in a variety of “spectral signatures” in aquatic plant species

The leaf reflectance spectra (280–887 nm) of two heterophyllous aquatic plant species Polygonum amphibium (L.) and Nuphar luteum (L.) were compared and their relation to physical properties of the leaves examined. In P. amphibium contrasting environmental conditions along water–land gradient affected the majority of anatomical and morphological properties of leaves, but less differences were observed in photosynthetic pigment and total flavonoid contents. Leaf mass per area (LMA), palisade mesophyll, leaf thickness, trichome length and anthocyanin content per dry mass were correlated to the different parts of spectra. In N. luteum natant and submerged leaves differed significantly in all measured parameters. Chlorophyll a, anthocyanin and carotenoid contents per dry mass were related to reflectance in the red region, while leaf thickness, anthocyanin and total flavonoid contents per leaf area were related to reflectance in the near infrared region. Redundancy Analysis (RDA) indicated that in P. amphibium the average length of trichomes and LMA explained 72% and 6% variability of the spectra, whereas in N. luteum anthocyanin content per dry mass, explained 57% variability of the spectra. The comparison of natant leaves of both species showed that they were more similar than different leaf types within the single species.     

水蓼对汞积累与分布的水培实验

通过水培实验,研究不同浓度的汞(0、0.5、1、10、20和50μg·L-1)对水蓼生长的影响及水蓼的耐受性表现。结果表明:在所处理的浓度范围内,水蓼生长与生理表现未受影响。水蓼根部具有最强的汞富集能力,富集系数高达531.5%。培养液中的汞浓度与水蓼茎、叶和根中汞的富集量呈显著正相关。在同一浓度时,随着培养时间的增长,水蓼体内汞含量不断增加。水蓼茎、叶和根亚细胞中的汞分布规律表现为:细胞壁>细胞器>细胞液,细胞壁对进入植物体内的汞有很强的束缚作用,限制其进入细胞质内部。     

2种蓼科植物体外抑菌试验研究

为研究蓼科植物水蓼、火炭母体外抑菌效果,制备水煎煮液,测定其对枯草芽胞杆菌、大肠埃希菌、金黄色葡萄球菌、黑曲霉、青霉、酿酒酵母的抑菌圈直径、最小抑菌浓度及灭菌前后水煎煮液抑菌效果的变化。结果表明：当水蓼液浓度大于0.6 g/mL,火炭母液浓度大于0.2 g/mL时,2者对细菌的抑菌效果均依次为：金黄色葡萄球菌〉大肠埃希菌〉枯草芽胞杆菌。2种水煎煮液对3种真菌无抑制作用。火炭母液对3种细菌的最小抑菌浓度分别为1/8、1/16和1/64 g/mL,都比水蓼液的结果1/4、1/8和1/16 g/mL低。药液经121℃高压蒸汽灭菌处理后,水蓼液对3种细菌的抑制作用有所增强,火炭母液则对金黄色葡萄球菌的抑制作用有所增强。2种水煎煮液对3种细菌均有不同程度的抑制作用,可考虑以其为原料进行植物源抗菌剂的开发,拓宽其应用领域。     

Quantifying aphid behavioral responses to environmental change

Aphids are the most common vector of plant viruses, and their feeding behavior is an important determinant of virus transmission. Positive effects of global change on aphid performance have been documented, but effects on aphid behavior are not known. We assessed the plant‐mediated behavioral responses of a generalist aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), to increased CO₂ and nitrogen when feeding on each of three host species: Amaranthus viridis L. (Amaranthaceae), Polygonum persicaria L. (= Persicaria maculosa Gray) (Polygonaceae), and Solanum dulcamara L. (Solanaceae). Via a family of constrained Markov models, we tested the degree to which aphid movements demonstrate preference among host species or plants grown under varying environmental conditions. Entropy rates of the estimated Markov chains were used to further quantify aphid behavior. Our statistical methods provide a general tool for assessing choice and quantitatively comparing animal behavior under different conditions. Aphids displayed strong preferences for the same host species under all growth conditions, indicating that CO₂‐ and N‐induced changes in plant chemistry have minimal effects on host preference. However, entropy rates increased in the presence of non‐preferred hosts, even when preferred hosts were available. We conclude that the presence of a non‐preferred host species affected aphid‐feeding behavior more than changes in plant leaf chemistry when plants were grown under elevated CO₂ and increased N availability.