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111.
郑磊  杞桑 《生态科学》1996,15(1):15-21
对我国首座核电站配套工程的抽水蓄能电站水库蓄水初期的浮游生物进行了调查。蓄水水库由上下两水库组成。两水库的浮游生物种类组成显著不同。上水库浮游植物共记录到30种(属),浮游动物12种(属);下水库浮游植物19种(属);浮游动物25种(属)。上下两水库浮游生物数量均较贫乏,表明浮游生物群落尚处于初期发育阶段,但在局部浅水处已出现小规模的蓝藻水花,认为是水库蓄水初期必然的结果  相似文献   
112.
The semi-dominant gai mutation of arabidopsis confers a dark-green dwarf phenotype resembling that of gibberellin (GA)-deficient mutants. In contrast to GA-deficient mutants, gai mutants do not respond to GA treatments and accumulate higher levels of bioactive GAs than are found in wild-type controls. The gai mutation thus alters the responses of plant cells to GA, indicating that the GAI (wild-type) gene product is involved in GA reception and/or signal transduction. Here we describe the isolation and preliminary characterization of a mutation, gas1-1, which is not linked to gai and which partially suppresses the effect of the gai mutation. Double mutant, gai gas1-1, homozygotes are less severely dwarfed and lighter green than gai GAS1 controls. However, comparisons of the effects of treatments with exogenous GA demonstrate that gas1-1 does not increase the GA responsiveness of the gai mutant. Thus the gas1-1 mutation appears to reduce the GA-dependency of plant growth, and identifies a gene (GAS1) whose product is a candidate GA signal-transduction component.Abbreviations GA gibberellin - GA3 gibberellic acid We thank Maarten Koornneef (Wageningen Agricultural University, The Netherlands) for providing mutant seed stocks; Mark Aarts and Bernard Mulligan (University of Nottingham, UK) for performing the -irradiation. This work was made possible by AFRC/BBSRC PMB Grants PG208/520 and PG208/0600, and by a grant from the Gatsby Charitable Foundation. P.C. was supported by a Human Capital and Mobility Fellowship from the EC.  相似文献   
113.
Inheritance of gusA and neo genes in transgenic rice   总被引:21,自引:0,他引:21  
Inheritance of foreign genes neo and gusA in rice (Oryza sativa L. cv. IR54 and Radon) has been investigated in three different primary (T0) transformants and their progeny plants. T0 plants were obtained by co-transforming protoplasts from two different rice suspension cultures with the neomycin phosphotransferase II gene [neo or aph (3) II] and the -glucuronidase gene (uidA or gusA) residing on separate chimeric plasmid constructs. The suspension cultures were derived from callus of immature embryos of indica variety IR54 and japonica variety Radon. One transgenic line of Radon (AR2) contained neo driven by the CaMV 35S promoter and gusA driven by the rice actin promoter. A second Radon line (R3) contained neo driven by the CaMV 35S promoter and gusA driven by a promoter of the rice tungro bacilliform virus. The third transgenic line, IR54-1, contained neo driven by the CaMV 35S promoter and gusA driven by the CaMV 35S.Inheritance of the transgenes in progeny of the transgenic rice was investigated by Southern blot analysis and enzyme assays. Southern blot analysis of genomic DNA showed that, regardless of copy numbers of the transgenes in the plant genome and the fact that the two transgenes resided on two different plasmids before transformation, the introduced gusA and neo genes were stably transmitted from one generation to another and co-inherited together in transgenic rice progeny plants derived from self-pollination. Analysis of GUS and NPT II activities in T1 to T2 plants provided evidence that inheritance of the gusA and neo genes was in a Mendelian fashion in one plant line (AR2), and in an irregular fashion in the two other plant lines (R3 and IR54-1). Homozygous progeny plants expressing the gusA and neo genes were obtained in the T2 generation of AR2, but the homozygous state was not found in the other two lines of transgenic rice.  相似文献   
114.
The cellular receptors that mediate binding and internalization of retroviruses have recently been identified. The concentration and accessibility of these receptors are critical determinants in accomplishing successful gene transfer with retrovirus-based vectors. Murine retroviruses containing ecotropic glycoproteins do not infect human cells since human cells do not express the receptor that binds the ecotropic glycoproteins. To enable human cells to become permissive for ecotropic retrovirus-mediated gene transfer, we have developed a recombinant adeno-associated virus type 2 (AAV) vector containing ecotropic retroviral receptor (ecoR) cDNA under the control of the Rous sarcoma virus (RSV) long terminal repeat (LTR) promoter (vRSVp-ecoR). Established human cell lines, such as HeLa and KB, known to be nonpermissive for murine ecotropic retroviruses, became permissive for infection by a retroviral vector containing a bacterial gene for resistance to neomycin (RV-Neo(r)), with a transduction efficiency of up to 47%, following transduction with vRSVp-ecoR, as determined by the development of colonies that were resistant to the drug G418, a neomycin analog. No G418-resistant colonies were present in cultures infected with either vRSVp-ecoR or RV-Neo(r) alone. Southern and Northern blot analyses revealed stable integration and long-term expression, respectively, of the transduced murine ecoR gene in clonal isolates of HeLa and KB cells. Similarly, ecotropic retrovirus-mediated Neo(r) transduction of primary human CD34+ hematopoietic progenitor cells from normal bone marrow was also documented, but only following infection with vRSVp-ecoR. The retroviral transduction efficiency was approximately 7% without prestimulation and approximately 14% with prestimulation of CD34+ cells with cytokines, as determined by hematopoietic clonogenic assays. No G418-resistant progenitor cell colonies were present in cultures infected with either vRSVp-ecoR or RV-Neo(r) alone. These results suggest that sequential transduction of primary human cells with two different viral vectors may overcome limitations encountered with a single vector. Thus, the combined use of AAV- and retrovirus-based vectors may have important clinical implications for ex vivo and in vivo human gene therapy.  相似文献   
115.
The HMV-II cells infected with influenza C virus were labeled with inorganic [32P]phosphate to identify phosphorylated proteins. Analysis by radioimmunoprecipitation with antiviral serum or monoclonal antibodies revealed that three major structural proteins of the virus, hemagglutinin-esterase (HE), nucleoprotein (NP), and matrix protein (M1) are all phosphorylated in both infected cells and virions. It was also observed that, in the presence of trypsin (10 μg/ml), the unphosphorylated form of the HE glycoprotein was cleaved efficiently whereas the phosphorylated form was not, raising the possibility that phosphorylation of HE may influence its susceptibility to degradation by proteolytic enzymes.  相似文献   
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本文报道了采自贵州沿河土地坳下奥陶统的牙形石,计有25属39种,根据牙形石组合特片分析,认为其与黔北其它地区下奥陶统牙形石组合面貌基本一致,属北大西洋牙形石动物地理区。  相似文献   
119.
低高径比喷射环流生化反应器流体力学和发酵性能的研究   总被引:5,自引:0,他引:5  
对高径比s≤2.5喷射环流生化反应器的流体力学和传质特性进行了系统的研究,选出反应器的最佳结构,关联出氧的体积传递系数(kLa)表达式。在此基础上,进行了谷氨酸发酵试验,摸索出用该设备进行各氨酸发酵的最佳工艺条件,使5批一次性投糖发酵的糖酸转化率达到50%以上。  相似文献   
120.
叙述了用时间分辨率纳秒荧光技术研究大豆磷脂或合成磷脂模型膜(脂质体)的物理状态变化与荧光寿命以及时间分辨各向异性测量参数变化相关性的实验结果。用荧光探剂MC540标记模型膜的结果表明,荧光寿命(τ)的变化与脂质/探剂比例、磷脂组成、磷脂的极性头部、脂肪酸酰链长度等有关。用DPH(1,6-diphenyl-1,3,5-hexatriene)标记磷脂模型膜的时间分辨各向异性分析结果表明,序参数(S)、  相似文献   
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