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利用不同激素组合对丝瓜愈伤组织诱导、芽的分化及试管苗快速繁殖进行了研究.结果发现不同外植体均易诱导愈伤组织,但愈伤组织分化芽较难,而外植体在一些激素组合中可直接形成不定芽;利用无菌苗的顶芽及腋芽,培养于附加6 BA1mg L+NAA0.5mg L或NAA1mg L的MS培养基上,获得了芽的快速增殖,形成芽簇,每丛芽数达6~8苗;试管苗于1 2MS+NAA0.5mg L生根培养基中6d生根率达到100%,获得完整再生植株.结果表明采用不同激素组合对丝瓜体细胞形态发生与发育的调控有决定性作用.  相似文献   
3.
Estimating the main axis of rotation (AoR) of a human joint represents an important issue in biomechanics. This study compared three formal methods used to estimate functional AoR, namely a cylindrical fitting method, a mean helical axis transformation, and a symmetrical axis approach. These methods were tested on 106 subjects undergoing navigated total knee arthroplasty. AoR orientation in 3D and in the frontal and coronal planes provided by each method was compared to the transepicondylar axis direction. Although all the methods resulted effective, significant differences were identified among them, relatively to the orientation in 3D and in the frontal plane projection. This was probably due to the presence of secondary rotations during the first degrees of knee flexion.  相似文献   
4.
Using “P nuclear magnetic resonance analysis, total inorganic polyphosphate in algae could be quantitatively estimated, For this purpose the algal suspension, which had been kept in cold trichloroacetic acid, was further treated with 6 mM EDTA, or the cells were kept in 2 N KOH containing 100 mM EDTA for 18 h at 37°C. These simple methods avoid hydrolysis of cellular inorganic polyphosphate and, therefore, are useful for the study of phosphorus metabolism in algae. The effects of these treatments on visualization of the signal for inorganic polyphosphate in nuclear magnetic resonance spectra were discussed in comparison with in vivo, ‘P nuclear magnetic resonance spectra of algae.  相似文献   
5.
Distribution pattern and levels of nitrogenase (EC 1.7.99.2) and glutamine synthetase (GS, EC 6.3.1.2) were studied in N2-, NO3? and NH4+ grown Anabaena cylindrica (CCAP 1403/2a) using immunogold electron microscopy. In N2- and NO3? grown cultures, heterocysts were formed and nitrogenase activity was present. The nitrogenase antigen appeared within the heterocysts only and showed an even distribution. The level of nitrogenase protein in the heterocysts was identical with both nitrogen sources. In NO3? grown cells the 30% reduction in the nitrogenase activity was due to a corresponding decrease in the heterocyst frequency and not to a repressed nitrogenase synthesis. In NH4? grown cells, the nitrogenase activity was almost zero and new heterocysts were formed to a very low extent. The heterocysts found showed practically no nitrogenase protein throughout the cytoplasm, although some label occurred at the periphery of the heterocyst. This demonstrates that heterocyst differentiation and nitrogenase expression are not necessarily correlated and that while NH4+ caused repression of both heterocyst and nitrogenase synthesis, NO3? caused inhibition of heterocyst differentiation only. The glutamine synthetase protein label was found throughout the vegetative cells and the heterocysts of all three cultures. The relative level of the GS antigen varied in the heterocysts depending on the nitrogen source, whereas the GS level was similar in all vegetative cells. In N2- and NO3+ grown cells, where nitrogenase was expressed, the GS level was ca 100% higher in the heterocysts compared to vegetative cells. In NH4+ grown cells, where nitrogenase was repressed, the GS level was similar in the two cell types. The enhanced level of GS expressed in heterocysts of N2 and NO3? grown cultures apparently is related to nitrogenase expression and has a role in assimilation of N2derived ammonia.  相似文献   
6.
通过硫酸铵分级沉淀、CM 5 2阳离子交换层析、蓝胶亲和层析和FPLCMonoS阳离子交换层析 ,从丝瓜籽抽提液中分离到一种多肽luffinP1。经MALDI TOFMS测得其分子量为 5 2 2 6 .5。氨基酸序列测定及同源性分析发现 ,luffinP1的N端 11个氨基酸序列与丝瓜籽中的一种 6 .5K富含Arg Glu的多肽AGRP的部分序列相同 ,并与南瓜籽中一种胰蛋白酶抑制剂C2肽具有很高的同源性。体外分析表明 ,luffinP1同时具有两种生物活性 :(1)对兔网织红细胞裂解液系统蛋白质生物合成有较强的抑制作用 ,IC50 为 0 .6nmol L ;(2 )具有明显的胰蛋白酶抑制活性 ,IC50 为 2 2 μmol L。  相似文献   
7.
张猛  张天宇 《菌物学报》2005,24(4):473-476
报道弯孢属的两个新种,柱弯孢Curvularia cylindrica和拟棒弯孢Curvularia trachycarpi,前者生于葱Allium fistulosum上,后者生于棕榈Trachycarpus fortunei上。柱弯孢的分生孢子柱状细长,4个隔膜,这是区别于其它种的显著特征。拟棒弯孢的形态与棒弯孢Cclavata B.L.Jain近似,但是其分生孢子明显的大于后者。研究标本保存在山东农业大学植物病理学标本室(HSAUP)。  相似文献   
8.
The particle and fluid dynamics in a rotating cylindrical filtration (RCF) system used for animal cell retention in perfusion processes was studied. A validated CFD model was used and the results gave numerical evidence of phenomena that had been earlier claimed, but not proven for this kind of application under turbulent and high mesh permeability conditions, such as bidirectional radial exchange flow (EF) through the filter mesh and particle (cells) lateral migration. Taylor vortices were shown to cause EF 10‐100 times higher than perfusion flow, indicating that EF is the main drag source, at least in early stages of RCF operation. Particle lateral migration caused a cell concentration reduction (CCR) near the filter surface of approximately 10%, contributing significantly to cell separation in RCF systems and giving evidence that the mesh sieving effect is not the sole phenomenon underlying cell retention in RCF systems. Filter rotation rate was shown to significantly affect both EF and CCR. A higher separation efficiency (measured experimentally at 2,000‐L bioreactor scale) and an enhanced CCR (predicted by the numerical simulations) were found for the same rotation rate range, indicating that there is an optimal operational space with practical consequences on RCF performance. Experimental data of a large‐scale perfusion run employing the simulated RCF showed high cell viabilities for over 100 days, which is probably related to the fact that the computed shear stress level in the system was shown to be relatively low (below 20 Pa under all tested conditions). © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1093–1102, 2014  相似文献   
9.
Abstract

Molecular dynamics simulation has been used to study diffusion of methane at ambient temperature in cylindrical pores at very low densities. The cylinders were modelled as a continuum solid which interacts with the methane in the radial direction only. At the lowest densities, the VACF method does not yield reliable values of the self diffusion coefficient, Ds , but a suitable choice of time step and run length enables values of Ds to be found from MSD plots that are below the classical Knudsen diffusion coefficients. When density is increased, Ds passes through a maximum although the adsorption isotherm remains inside the Henry law region. Maxima are found for two cylinder radii and for two adsorbent field strengths. The existence of a maximum is attributed to transient intermolecular interactions. Analysis of a molecular trajectory demonstrates that long diffusion paths can be triggered by the rare event of an intermolecular encounter which forces a molecule into the repulsive part of the wall potential. At sufficiently high density, subsequent collisions quench the tendency towards long paths, and Ds decreases again. The issue of simulation artefact as a source of these observations is discussed.  相似文献   
10.
Static displacements in Pacinian corpuscles (PCs) were measured using video microscopy. Mechanical stimuli of 10–40?µm steps were applied to the PC capsule surfaces using cylindrical contactors with different diameters. Displacements parallel to the stimulation axis were measured at various locations in the focal plane of the optical setup. In contrast to previous data in the literature, the displacements within the corpuscle were found to be linearly related to the indentation amplitude. Displacements decreased as a function of lamella depth, with a more negative slope close to the surface and less negative slope at deeper locations. The experimental data were compared to the predictions of a previous mechanical model, and to the results of two new models: () elastic semi-infinite continuum model; () ovoid isotropic finite-element model. Although the previous model did not specify displacement boundary conditions, it predicted the current experimental results well. On the other hand, the experimental displacements were found to be smaller than those predicted by the semi-infinite continuum and finite-element models. However, both semi-infinite continuum and finite-element models yielded close results, which show that the three-dimensional ovoid geometry of the corpuscle is not the primary factor for determining the displacements in physiological conditions. Furthermore, simulations with the finite-element model using a wide range of material properties yielded similar results. This supports the hypothesis that a homogeneous isotropic model for the PC cannot predict experimental results. The modeling analyses suggest that the experimental results are largely affected by the displacement of the incompressible interlamellar fluid and the layered structure of the corpuscle.  相似文献   
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