细胞分裂素的测定及其转基因植物的基因表达和调控的研究

细胞分裂素是一类重要的植物激素，它参与调节许多植物的生命活动过程。本文从几个方面研究了细胞分裂素的作用。 在细胞分裂素的活性测定中，通过改进尾穗蔸苋红素合成法建立了一种简便、准确的生物试法，同时还建立了根据物理化学和免疫学原理而测定细胞分裂素的HPLC和ELISA方法，使得细胞分裂素的定量更加准确。经过对上述三种方法的相互验证实验表明，同时采用二种方法可以保证细胞分裂素分析的准确和可靠。 细胞分裂素可以促进黄瓜子叶的扩张。利用离体黄瓜子叶，分析BA诱发其扩张与子叶内源细胞分裂素之间的关系，实验证明，BA能促进玉米素及其核苷的迅速积累，进而诱发子叶的扩张。上述结果还表明，黄瓜子叶可能具有合成细胞分裂素的能力。 荸荠球茎是一种贮藏器官，但实验测定发现其中含有细胞分裂素的生理活性形式——异戊烯基腺嘌呤核苷(iPA)，而且合成它的前体腺嘌呤的含量也十分丰富，考虑到球茎与种子的类似之处，推测它可能做为合成细胞分裂素的一个源，而且其合成途径可能有别于植物其它组织。 农杆菌中的异戊烯基转移酶(ipt)基因是负责细胞分裂素生物合成的关键基因。将ipt基因克隆后对其启动子进行了改造，分别构建了如下三种基因：(1) ipt启动子+ipt编码区和3，区(ipt)，(2)磷酸核酮糖羧化酶小亚基启动子SSU 301+ipt编码区和3，区(SSU -ipt)，(3)豌豆种子特异性启动子viciln+ipt编码区和3，区(vic-ipt)。上述三种基因经农杆菌介导转化烟草，获得了16株再生植株，经Southern杂交证明其中15株的基因组上含有正常整合的ipt基因。Northern杂交表明有13株转基因烟草中的ipt基因能转录出大小正常的ipt mRNA并促进了细胞分裂素的生物合成。 实验表明，转基因烟草中ipt基因的表达受到多种因素的调控。首先启动子决定了ipt基因的表达模式，SSU -ipt基因的表达受光的诱导，黑暗中这种基因的转录完全停止，而vic-ipt基因的表达是种子特异性的，它不在烟草营养生长器官如根、茎、叶和愈伤组织中表达。第二，生长素能降低ipt基因的表达活性。第三，在整体植物的根中，存在某些反式因子，能够控制ipt基因的过量表达，这其中可能涉及到细胞内的蛋白因子、基因的甲基化作用及细胞分裂素的反馈调节等。 vic-ipt基因在烟草种子中的特异性表达导致种子内形成了一个细胞分裂素合成的源(source)。对种子中营养物质积累的研究表明，ipt基因的表达促进了种子干物质的积累，其中作用最明显的是增加种子内蛋白质的合成。转入vic-ipt基因后的烟草种子其萌发率没有显著变化，但幼苗的生长速率明显加快，这表明细胞分裂素能调节植株的生长。 通过Northern杂交检测转基因烟草中基因表达的调控，实验证明，ipt基因的表达明显抑制一组植物病理相关蛋白(PR)基因的转录活性，这组基因编码：几丁质酶，β-1，3一葡萄糖苷酶，伸展蛋白和渗调蛋白。对这些调控作用的生理学意义还有待进一步探索。 上述结果表明，在高等植物中，除了传统上认为根是合成细胞分裂素的部位之外，其它组织和器官也具有合成细胞分裂素的能力，其中合成能力最强的是一些离体组织和贮藏器官。农杆菌中的细胞分裂素生物合成基因(ipt)能够在高等植物的基因组中正常的整合和表达，并受到植物体内生理、发育等多种因素的调控，而与整体植物的正常生理过程协调一致。ipt基因的表达还能够调节植物体的生长和发育，包括种子发育时营养物质的积累、幼苗的生长和某些相关基因的表达。对上述问题的深入研究,必将促进细胞分裂素及其相关生理学和发育学研究的进展。

An experimental study on turbulent coherent structures near a sheared air-water interface

The turbulence structures near a sheared air-water interface were experimentally investigated with the hydrogen bubble visualization technique. Surface shear was imposed by an airflow over the water flow which was kept free from surface waves. Results show that the wind shear has the main influence on coherent structures under air-water interfaces. Low- and high- speed streaks form in the region close to the interface as a result of the imposed shear stress. When a certain airflow velocity is reached, "turbulent spots" appear randomly at low-speed streaks with some characteristics of hairpin vortices. At even higher shear rates, the flow near the interface is dominated primarily by intermittent bursting events. The coherent structures observed neat sheared air-water interfaces show qualitative similarities with those occurring in near-wall turbulence. However, a few distinctive phenomena were also observed, including the fluctuating thickness of the instantaneous boundary layer and vertical vortices in bursting processes, which appear to be associated with the characteristics of air-water interfaces.

Underwater Acoustics and Cavitating Flow of Water Entry

The fluid mechanics of water entry is studied through investigating the underwater acoustics and the supercavitation. Underwater acoustic signals in water entry are extensively measured at about 30 different positions by using a PVDF needle hydrophone. From the measurements we obtain (1) the primary shock wave caused by the impact of the blunt body on free surface; (2) the vapor pressure inside the cavity; (3) the secondary shock wave caused by pulling away of the cavity from free surface; and so on. The supercavitation induced by the blunt body is observed by using a digital high-speed video camera as well as the single shot photography. The periodic and 3 dimensional motion of the supercavitation is revealed. The experiment is carried out at room temperature.

The Liquefaction and Displacement of Highly Saturated Sand under Water Pressure Oscillation

In order to investigate the characteristics of water wave induced liquefaction in highly saturated sand in vertical direction, a one-dimensional model of highly saturated sand to water pressure oscillation is presented based oil the two-phase continuous media theory. The development of the effective stresses and the liquefaction thickness are analyzed. It is shown that water pressure oscillating loading affects liquefaction severely and the developing rate of liquefaction increases with the decreasing of the sand strength or the increasing of the loading strength. It is shown also that there is obvious phase lag in the sand Column. If the sand permeability is non-uniform, the pore pressure and the strain rise sharply at which the smallest permeability occurs. This solution may explain Why the fracture occurs in the sand column in some conditions.

Some characteristics of low-speed streaks under sheared air-water interfaces

The characteristics of low-speed fluid streaks occurring under sheared air-water interfaces were examined by means of hydrogen bubble visualization technique. A critical shear condition under which the streaky structure first appears was determined to be u(tau) approximate to 0.19 cm/s. The mean spanwise streak spacing increases with distance from the water surface owing to merging and bursting processes, and a linear relationship describing variation of non-dimensional spacing <(+)over bar> versus y(+) was found essentially independent of shear stress on the interface. Values of <(+)over bar>, however, are remarkably smaller than their counterparts in the near-wall region of turbulent boundary layers. Though low-speed streaks occur randomly in time and space, the streak spacing exhibits a lognormal probability distribution behavior. A tentative explanation concerning the formation of streaky structure is suggested, and the fact that <(+)over bar> takes rather smaller values than that in wall turbulence is briefly discussed.

Experimental study on pore pressure in rock-soil slope during reservoir water level fluctuation

A test system was developed for measuring the pore pressure in porous media, and a new model was devised for the pore pressure testing in both saturated and unsaturated rock-soil. Laboratory experiments were carried out to determine the pore pressure during water level fluctuation. The variations of transient pore pressure vs. time at different locations of the simulated rock-soil system were acquired and processed, and meanwhile the deformation and failure of the model are observed. The experiment results show that whether the porous media are saturated or not, the transient pore pressure is mainly dependent on the water level fluctuation, and coupled with the variation of the stress field.

Studies on the phase diagram of the surfactant/1-pentanol water ternary system I: The isotropic phases

The phase diagram of the dodecyl dimethyl ammonium hydroxyl propyl sulfonate(DDAHPS)/1-pentanol(C5H11OH)/water ternary system has been established. It contains two isotropic monophase regions (L-1 and L-2) and a liquid crystalline region (L.C.). The isotropic phase regions have been investigated by means of Raman spectroscopy and conductivity.

Sensitivity Analysis of Dimensionless Parameters for Physical Simulation of Water-Flooding Reservoir

A numerical approach to optimize dimensionless parameters of water-flooding porous media flows is proposed based on the analysis of the sensitivity factor defined as the variation ration of a target function with respect to the variation of dimensionless parameters. A complete set of scaling criteria for water-flooding reservoir of five-spot well pattern case is derived from the 3-D governing equations, involving the gravitational force, the capillary force and the compressibility of water, oil and rock. By using this approach, we have estimated the influences of each dimensionless parameter on experimental results and thus sorted out the dominant ones with larger sensitivity factors ranging from10-4to10-0 .

Characterization of Air-Water Two-Phase Vertical Flow by Using Electrical Resistance Imaging

The characterization of air-water two-phase vertical flow in a 12 m flow loop with 1.5 m of vertical section is studied by using electrical resistance tomography (ERT). By applying a fast data collection to a dual-plane ERT sensor and an iterative image reconstruction algorithm, relevant information is gathered for implementation of flow characteristics, particularly for flow regime recognition. A cross-correlation method is also used to interpret the velocity distribution of the gas phase on the cross section. The paper demonstrates that ERT can now be deployed routinely for velocity measurements and this capability will increase as faster measurement systems evolve.

Simulations of oil spread on a water surface

Numerical simulation of an oil slick spreading on still and wavy surfaces is described in this paper. The so-called sigma transformation is used to transform the time-varying physical domain into a fixed calculation domain for the water wave motions and, at the same time, the continuity equation is changed into an advection equation of wave elevation. This evolution equation is discretized by the forward time and central space scheme, and the momentum equations by the projection method. A damping zone is set up in front of the outlet boundary coupled with a Sommerfeld-Orlanski condition at that boundary to minimize the wave reflection. The equations for the oil slick are depth-averaged and coupled with the water motions when solving numerically. As examples, sinusoidal and solitary water waves, the oil spread on a smooth plane and on still and wavy water surfaces are calculated to examine the accuracy of simulating water waves by Navier-Stokes equations, the effect of damping zone on wave reflection and the precise structures of oil spread on waves.

Experimental Investigation and Numerical Simulation on the Effect of Fissure Water Pressure in Vertical Sliding Surface

This paper studies the effect of fissure water pressure in different fractures on the critical angle of landslide by laboratory investigation and numerical simulation in order to understand the mechanisms of fissure water pressure on landslide stability. Laboratory observations show that the effect of fissure water pressure on the critical angle of landslide is little when the distance between water-holding fracture and slope toe is three times greater than the depth of fissure water. These experimental results are also simulated by a three-dimensional face-to-face contact discrete element method. This method has included the fissure water pressure and can accurately calculate the critical angle of jointed slope when fissure water pressure in vertical sliding surface exists. Numerical results are in good agreement with experimental observations. It is revealed that the location of water-holding structural surface is important to landslide stability. The ratio of the distance between water-holding fissure and slope toe to the depth of fissure water is a key parameter to justify the effect of fissure water pressure on the critical angle of landslide.

Viscosity, Surface Tension, and Atomization of Water-Methanol and Diesel Emulsions

This article is the result of experimental studies of the rheologv, viscosities, surface tensions, and atomization of water-methanol and diesel emulsions. The Span 80 and Tween 60 are employed to make three emulsifying agents, Y01, Y02, and Y03, with viscosity of 1.32-1.5 Pa s and HLB values of 5.36, 4.83, and 4.51, respectively. In the water-in-oil emulsions, the aqueous phase is between 10% and 50%; the agent concentration added is 0.8-8.0%. The viscosity of the emulsions is 0.003-0.02 Pa s, and the surface tens ion is 0.04-0.1 N/m. The types and concentrations of agents significantly influence the viscosity of the emulsions, and the higher concentration of the aqueous phase (<50%) in creases the viscosities of the emulsions, especially for higher agent concentration. Interfacial membrane and HLB values of the agents can explain all these phenomena. Higher aqueous phase concentration and agent viscosity results in larger Sauter mean diameter.

Studies on the phase diagram of the surfactant/1-pentanol water ternary system II: The liquid crystalline phase

The phase behavior of liquid crystalline in the ternary system of dodecyl dimethyl ammonium hydroxyl propyl sulfonate(DDAHPS)/1-pentanol(C5H11OH)/water deuteron (D2O) has been investigated by polarizing optical microscopy, H-2 NMR spectroscopy methods. The results indicate that two kinds of liquid crystals (the lamellar, and the hexagonal) exist in the liquid crystalline phase region. In this paper, we also use the polarized Raman spectroscopy method to measure the values of the order/disorder parameters and the values of the environment polarity parameters for the samples selected from the liquid crystalline phase region, and compare these two parameters of the samples with those of solid state DDAHPS and liquid state pentan-1-ol.

Fourier Transform Method for Measuring the Micro Amplitu of Water Surface Waves

采用一种非接触的光学方法傅立叶变换莫尔法(Fourier transform method),结合数字图像处理技术,对微幅振荡的水表面波的振幅进行测量.它是对全场中每一个像素点进行测量,比接触测量法具有更高的灵敏度.它为微幅水表面波振幅的测量提供了一种手段.通过将计算机生成的周期性光栅图像经投影机直接投影到被测物体的参考平面,经CCD摄像头、图像板捕捉存储形成数字化的光栅图像,利用傅立叶变换莫尔法处理光栅图像,从而获得包含有水表面波的振幅的相位信息,再经适当的几何变换获得振幅信息.我们在垂直振荡装置上进行了不同激励频率和不同振幅的表面波的振幅测量.