抗缺铁葡萄砧木的鉴定及指标筛选

以14个葡萄砧木品种为试材,研究了根系的铁吸收特性及其中8种砧木的缺铁适应反应,初步确定铁吸收动力学、根际pH值、根系的铁还原能力作为评价铁高效葡萄砧木的指标。筛选出SO4、5BB、420A为铁高效葡萄基因型砧木;公酿1号、北醇、美山、1103P为铁中等效率葡萄基因型砧木;无毛河岸、自由、道格、贝达、775P、VR043-43、3309C为铁低效葡萄基因型砧木。     

两个棉铃虫酯酶基因(001f和001g)在杆状病毒表达载体系统(BEVS)中的表达及酶活分析

昆虫羧酸酯酶(carboxylesterases,CarEs)对有机磷、拟除虫菊酯、氨基甲酸酯等三大类化学杀虫剂的代谢解毒作用是昆虫代谢抗性产生的一种重要机制.为明确棉铃虫(Helicoverpa armigera)两个酯酶基因001f和001g在代谢抗性中的作用,本研究基于杆状病毒表达载体系统(BEVS)在草地夜蛾(Spodoptera frugiperda)Sf9细胞系中成功表达了酯酶基因001f和001g,表达产物经非变性聚丙烯酰胺凝胶电泳和α-乙酸萘酯染色,结果表明,两个酯酶的条带染色很深,染色条带主要分布在相对迁移率(Rm)值为0.27～0.36和0.37～0.48之间的两个区域.进一步采用酶标仪测定了表达产物对α-乙酸萘酯(α-naphthyl acetate)和4-硝基苯基乙酸酯(para-nitrophyl acetate)的酶促代谢动力学特性,结果表明,两个酯酶对底物均有极强的亲和力和非常高效的催化效率,其对α-乙酸萘酯的亲和系数(Km值)分别为(3.9±0.6)和(3.3±0.4) μmol/L,速率常数(kcat/Km值)高达(95±9.3)和(26.5±1.9) μmol-1·s-1·L;相比较而言对于4-硝基苯基乙酸酯的kcat/Km值较低(分别为(4.47±0.33)和(12.8±0.10) μmol-1 ·s-1·L).上述结果在生化水平上证实了两个酯酶均具有较强代谢作用,预示着这两个酯酶基因与棉铃虫的代谢抗性可能相关,并可能对有机磷、拟除虫菊酯等化学杀虫剂也具有一定代谢解毒作用.     

不同水稻品种对铵态氮和硝态氮吸收特性的研究

采用水培方法研究了不同形态氮素对武育粳 3号 (常规粳稻 )和扬稻 6号 (常规籼稻 )生长的影响及其水稻苗期对NH 4 N和NO-3 N的吸收动力学特征。结果表明 :不同形态氮素对水稻生长影响差异显著 ,铵硝混合营养下水稻的生长最优 ;扬稻 6号比武育粳 3号具有更强的氮素吸收能力 ;不论武育粳 3号或是扬稻 6号 ,单一氮源时NO-3 的Km 值均大于NH 4 ,说明水稻对NH 4 的亲和力大于NO-3 ,武育粳 3号对NH 4 的最大吸收速率小于NO-3 ,而扬稻 6号则极为接近 ;NH 4 的存在均显著降低两个水稻品种对NO-3的吸收速率 ,武育粳 3号和扬稻 6号的NO-3 的Vmax分别比单一硝营养减小 1/ 2和 2 / 3,NO-3 的存在不影响武育粳 3号对NH 4 的吸收速率 ,但使扬稻 6号对NH 4 的吸收速率减小     

Acetylcholinesterase in selected plant-parasitic nematodes: Inhibition, kinetic and comparative studies

The in vitro inhibition potency of some organophosphates (OPs) and carbamates (CAs) which are widely used to control plant-parasitic nematodes on acetylcholinesterase (AChE) of Meloidogyne javanica, Heterodera avenae and Tylenchulus semipenetrans, the major pathogens responsible for the damage of a wide range of crops in Al-Qassim region, Saudi Arabia was examined. AChE of H. avenae activity was 1.58- and 1.51-fold greater than that of T. semipenetrans or M. javanica, respectively. The order of inhibition potency of the tested compounds against T. semipenetrans AChE was: carbofuran > paraoxon > oxamyl > fenamiphos > phorate-sulfoxide > aldicarb, where the corresponding concentrations that inhibited 50% of the nematode AChE activity (I₅₀) were 5 × 10⁻⁸, 7 × 10⁻⁷, 7.5 × 10⁻⁷, 2 × 10⁻⁶, 2 × 10⁻⁴ and 2 × 10⁻³ M, respectively. Paraoxon, fenamiphos and carbofuran exhibited high inhibition potency against M. javanica AChE where the I₅₀ values were below 1 nM. Phorate-sulfoxide and aldicarb were potent inhibitors of M. javanica AChE with I₅₀ values of 3.8 and 8 nM, respectively, while oxamyl exhibited low inhibition potency with I₅₀ of 15 nM. Fenamiphos and paraoxon showed the highest I₅₀ values of <100 μM against H. avenae followed by oxamyl (I₅₀ < 1 mM), whereas paraoxon, carbofuran and aldicarb showed low potency with I₅₀ values >1 mM. All the tested compounds exhibited high inhibition potency to AChE of M. javanica than T. semipenetrans or H. avenae. Except phorate-sulfoxide in M. javanica the inhibition pattern and implied mechanism for all the tested compounds for the three nematodes is suggested to be a linear mixed type (a combination of competitive and non-completive type).     

Activation kinetics of cetylpyridinium chloride on the prophenol oxidase from pupae of blowfly (Sarcophaga bullata)

Prophenol oxidase (PPO) (EC 1.14.18.1) is isolated from pupae of blowfly (Sarcophaga bullata) and purified by employing ammonium sulfate fractionation, ion-exchange chromatography on DEAE-cellulose, and gel filtration through Sephadex G-100 column chromatography. The enzyme exists in a latent or inactive state. Cetylpyridinium chloride (CPC), a cationic detergent, is found to activate the PPO activity. The activation of the enzyme by CPC has first been studied by using the kinetic method of the substrate reaction described by Tsou. The results show that the enzyme is activated by a complexing scheme that has not been previously identified. The enzyme first reversibly and quickly binds CPC and then undergoes a slow reversible active course. The activation reaction is a single molecule reaction and the apparent activation rate constant is dependent on the CPC concentration with the function relationship fit with a hyperbola. The micro rate constants of activation and the association constant are determined from the measurements. Substrate binding does not affect the micro rate constants of activation by CPC.     

土壤磷扩散规律及其能量特征的研究 Ⅲ.土壤磷扩散的动力学及能量特征

用³²P标记扩散池法测定了不同时间下土壤磷的扩散量,并用5种动力学模型对其拟合,结果表明土壤磷扩散过程最符合抛物线扩散方程。20%含水量下,磷扩散速率温度商Q₁₀。为1.20左右,与扩散是一个物理过程相吻合。由阿尼乌斯公式求得的磷扩散活化能(E_a^D)随土壤水分增加而降低;在土壤水低吸力范围内(<10⁵Pa水吸力)为12-34kJ/mol,平均为25kJ/mol左右,与溶液中离子扩散活化能较接近,说明低吸力下磷扩散主要在液相进行。将绝对反应速率理论移植用于磷扩散,所求出的磷扩散净活化能、活化熵变、活化焓变和活化自由能变在供试土壤中相同含水量下均呈规律性变化,且与E_a^D变化趋势基本一致,证明这些参数可用于表征磷扩散的能量特征。     

多维隔振装置自由振动方程及其解

通过多方位多层次结构组合实现多维隔振时,其结构复杂、难度大,因此提出以反向对称布置双直角Stewart机构及上、下平台组成多维隔振装置,利用一层结构实现多维隔振,建立了自由振动方程并进行求解.由解看出,该装置固有频率在5 Hz以下,振动衰减较快.使用该装置,仿真可实现沿坐标轴的3个移动和绕坐标轴的3个转动,加速度传递系数均小于1.依据所推导的公式,确定该装置的刚度系数、阻尼系数和结构尺寸,可将该装置用于多维隔振.     

蒜氨酸酶动力学特性研究

本文研究了蒜氨酸酶的动力学特性,结果表明其最适温度为３０℃,最适ｐＨ值为６．２４,以蒜氨酸为底物,其最大反应速度Ｖｍａｘ＝１２０ｕｎｉｔｓ／ｍｇｏｆｐｒｏｔｅｉｎ,米氏常数Ｋｍ＝６．０２×１０－３ｍｏｌ／Ｌ。本文同时研究了抑制与激活剂对蒜氨酸酶活性的影响。     

动态水压下非旋转式折射喷头水力特性

为解决非旋转式折射喷头水量分布集中,打击动能较大的问题,构建了动态水压喷灌测试平台。选择Nelson D3000型喷头为研究对象,施加以三角函数型动态变化的水压,对喷头的径向水量分布与能量分布进行测试,并与恒压条件下的水量和能量分布进行对比。结果表明:构建的动态水压测试平台能够满足对动态供水压力的要求,施加了动态水压的Nelson D3000型喷头径向湿润范围由恒压时的0.85~1.36 m增加到2.55~4.42 m,喷灌强度最大值降低67.6%~78.4%,能量通量密度最大值降低52.9%~71.6%,说明采用动态水压供水可以有效地改善Nelson D3000型喷头的径向水量分布和能量分布。