玉米根系吸水能力细胞水平的杂种优势

在人工气候室水培条件下,以玉米(ZeamaysL.)杂交种F1代户单4号及其母本天四和父本478为材料,用细胞压力探针技术研究了正常供水和PEG-6000模拟–0.2MPa水分胁迫条件下,玉米根皮层细胞水分关系参数的基因型差异。结果表明,根皮层细胞的直径、长度和体积均为F1代>母本>父本;正常供水条件下3个玉米品种的根皮层细胞膨压均在0.6MPa左右且品种间差异不显著,水分胁迫抑制了细胞的延伸生长且F1代和母本的细胞膨压显著高于父本;根皮层细胞壁体积弹性模量均为父本>母本>F1代,水分胁迫条件下的品种间差异显著;与正常供水条件相比,水分胁迫条件下细胞膨压显著降低,而弹性模量则大幅度提高;在两种水分条件下,水分跨细胞膜运转的半时间均为父本>母本>F1代,且半时间在水分胁迫条件下均显著高于正常供水条件下;HgCl2处理引起了半时间的延长,2-巯基乙醇则部分逆转了HgCl2的效应;在两种水分条件下,根皮层细胞水导均为F1代>母本>父本且品种间差异显著,水分胁迫则显著降低了细胞水导。试验证明杂交种F1代的细胞水平根系吸水能力优于亲本,体现了杂种优势。

汞-豆磺隆，呋喃丹污染土壤的酶特征研究

采用模拟方法，研究了Hg、豆磺隆和呋喃丹对不同肥力草甸棕壤和黑土转化酶、脲酶、中性磷酸酶活性的影响及汞和2种农药之间对土壤酶活性的交互作用，并对不同温度条件下，汞、豆磺隆对土壤脲酶动力学参数的影响进行了研究，为建立重金属、农药污染土壤酶监测指标体系和土壤污染酶修复工作提供理论参考。 试验结果表明，几种酶对土壤汞污染的敏感性顺序为脲酶 > 转化酶 > 中性磷酸酶，有机质含量高的土壤对汞抑制土壤酶的效应缓冲能力普遍较强，HgCl2浓度与脲酶和转化酶活性之间的关系均可用对数方程均可很好的描述，由于脲酶对汞的敏感性较强，可在一定程度上表征汞的污染程度，在建立土壤汞污染酶监测方法体系的领域，具有一定的研究潜力；而2种农药对3种土壤酶活性的影响较小，规律性较差，总体来说，豆磺隆对土壤脲酶有激活作用，对转化酶和土壤中性磷酸酶活性表现出抑制作用；呋喃丹对3种酶均有微弱的激活作用。 汞和豆磺隆或呋喃丹之间对土壤转化酶、脲酶、中性磷酸酶多数情况下均存在不同程度的交互作用，既有降低两种污染物毒性的拮抗作用，也有增强毒性的协同作用，因土壤类型、土壤肥力、污染物浓度和酶种类不同而存在差异。 除个别土样外，Hg浓度与脲酶动力学参数Km和Vmax和Vmax /Km值之间均呈显著(P < 0.05)或极显著(P < 0.01)负相关，这一现象符合典型的反竞争性抑制类型；豆磺隆对脲酶的激活效应很可能是由于其促进酶促反应初速度的提高引起的；Hg、豆磺隆同时添加对脲酶动力学参数Km、Vmax和Vmax /Km值的影响与单一添加Hg条件下相似，但由于豆磺隆的加入使规律性趋于复杂。 本试验温度范围内，对于汞污染，土壤对脲酶的保护能力随温度升高而有所下降；而对于豆磺隆单一污染、汞和豆磺隆复合污染污染，污染物对脲酶动力学参数的影响与温度之间没有显著关系。

汞对土壤酶活性的影响

利用室内模拟方法,研究了重金属Hg对不同土样脲酶、转化酶和中性磷酸酶活性的影响.结果表明,Hg可显著地抑制土壤脲酶和转化酶的活性,但不同土样Hg对两种酶活性的抑制程度有很大差别.HgCl2浓度与两种酶活性之间的关系均可用对数方程很好地描述(P<0.05).4个土样的脲酶ED50(生态剂量)分别为87.99、5.47、24.05和19.88mg.kg-1;转化酶的ED50分别为76.68、727.49、236.52和316.59mg.kg-1.脲酶对Hg污染比转化酶敏感;有机质对土壤酶活性有一定的保护作用.除连续2年施用大量有机肥的草甸棕壤土样中Hg对中性磷酸酶有显著的激活作用外(P<0.05),其它土样无显著变化,表明中性磷酸酶活性对Hg污染反应不敏感.

Synthesis and metallophilic properties of troponoid thiocrown ethers

A new class of ionophores with troponoid and thiocrown ether units was prepared. Cation-binding properties of troponoid dithiocrown ethers were characterized using UV and NMR spectroscopies. They have affinity with metal ions; in particular, they showed high affinity with Hg2+. Transport of Hg2+ through a CHCl3 liquid membrane with troponoid dithiocrown ethers was examined in a U-type cell. From an aqueous solution of HgCl2 and CuCl2, Hg2+ is transferred selectively and smoothly, while the Cu2+ remained quantitatively in the original solution. The cavity size of dithiocrown ethers is one of the requirements for effective extraction and transport of Hg2+. However, derivatives with a smaller cavity still extract and transport Hg2+. A polymer-supported troponoid dithiocrown ether was prepared to transport Hg2+ effectively and repeatedly. Comparing the troponoid dithiocrown ether with the benzenoid dithiocrown ether with a similar cavity size, the former was more effective for the transport of Hg2+. It is proposed that the tropone ring assisted the release of Hg2+ from the complex by Coulomb repulsion between the protonated tropone ring and Hg2+.

NMR and pattern recognition studies on the acute biochemical effects of Lu(NO3)(3)

Pattern recognition methods were applied to the analysis of 600 MHz H-1 NMR spectra of urine from rats dosed with compounds that induced organ-specific damage in the liver and kidney. Male Wistar rats were separated into groups (n=4) and each was treated with one of following compounds: HgCl2, CCl4, Lu(NO3)(3) and Changle (a kind of rare earth complex mixed with La, Ce, Pr and Nd). Urine samples from the rats dosed with HgCl2, CCl4 and Lu(NO3)(3) were collected over a 24 h time course and the samples from the rats administrated with Changle were gained after 3 months. These samples were measured by 600 MHz NMR spectroscopy. Each spectrum was data-processed to provide 223 intensity-related descriptors of spectra. Urine spectral data corresponding to the time intervals, 0-8 h (HgCl2 and CCl4), 4-8 (Lu(NO3)(3)) h and 90 d (Changle) were analyzed using principal component analysis (PCA). Successful classification of the toxicity and biochemical effects of Lu(NO3)(3) was achieved.