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51.
E. A. Matibiri S. H. Mantell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,88(8):1017-1022
An effective selection system preceded by double inactivation of parental protoplasts was used to transfer Nicotiana suaveolens Leh. cytoplasmic male sterility into a commercial tobacco (N. tabacum L.) breeding line. Mesophyll protoplasts from transformed plants of N. tabacum cultivar WZ2-3-1-1 possessing a neomycin phosphotransferase II gene were used as the nuclear donors, while those isolated from N. suaveolens plants carrying a chloroplast mutation for resistance to spectinomycin, induced using nitrosomethyl urea, were the cytoplasm donors in somatic cybridizations. Prior to fusion, nuclear donor protoplasts were inactivated with iodoacetamide or rhodamine 6G, while those of the cytoplasm donor were inactivated by X-irradiation. The resultant microcalli were cultured on a shoot regeneration medium containing both kanamycin and spectinomycin to select cybrids. Only regenerants that had typical characteristics of the N. tabacum cultivar were selected for transfer to the glasshouse. Four putative cytoplasmic male-sterile (CMS) plants, out of a total of 44 regenerated plants transferred to the glasshouse, were obtained. Intraspecific somatic transfers of the CMS trait between N. tabacum cultivars with distinctlydifferent morphologies using single inactivation and nonselective shoot regeneration medium were demonstrated. The implications of the results for practical tobacco breeding as a means of circumventing lengthy backcrossing procedures are discussed. 相似文献
52.
ts7, a temperature-sensitive mutant defective in neuraminidase (NA) of influenza B/Kanagawa/73, lacks NA enzymatic activity at the nonpermissive temperature (37.5 C). When MDCK cells were infected with the mutant at the permissive temperature (32 C) and exposed to pH 5.2 medium, extensive cell fusion occurred. In contrast, at the nonpermissive temperature cells did not show cell fusion at all unless they were pretreated with trypsin, suggesting that at 37.5 C the hemagglutinin (HA) of ts7 is expressed at the cell surface in an uncleaved form. It was also found that the replacement of RNA segment 6 of ts7 with that of wild-type B/Lee resulted in the emergence of low pH-induced fusion activity as well as NA enzymatic activity at the incubation temperature of 37.5 C and that the addition of bacterial NA to the cultures infected with ts7 at 37.5 C early in infection brought about low pH-induced cell fusion. We suggest that the removal of neuraminic acid from the carbohydrate moiety of HA by NA is essential for the cleavage of HA by cellular protease. 相似文献
53.
新型双分子细胞因子融合蛋白研究进展 总被引:7,自引:0,他引:7
细胞因子通过相互协调、相互制约在体内发挥着重要的免疫调节作用,利用细胞因子的这一特点,近年来国内外设计并构建了新型的第二代细胞因子,即利用基因工程技术和蛋白质工程技术将两种细胞因子合二为一,使之成为具有多功能的嵌合蛋白新品种,为细胞因子的理论研究及临床应用提供了新的手段与方法. 相似文献
54.
人重组IL6/IL2融合蛋白的变性、复性及纯化 总被引:1,自引:0,他引:1
经超声破碎,分离已表达CH925包涵体,较系统地研究变性剂浓度、融合蛋白浓度对蛋白折叠的影响.在还原型及氧化型谷胱甘肽复性条件下,成功地将融合蛋白CH925折叠成具有IL6及IL2双活性蛋白,IL6的比活为2.3×108U/mg, IL2比活为2.2×106U/mg.经阴离子交换、凝胶过滤层析,获得一定纯度的CH925,配合反相HPLC.洗脱收集蛋白峰,CH925纯度为98%. 相似文献
55.
Tadeusz Janas Agnieszka Janiak-Osajca Teresa Janas 《Journal of biological physics》1993,19(4):295-308
The study presents an application of the theory of homeomorphic transformations of topological manifolds and the operation of the connected sum of manifolds for topological analysis of membrane transformations during the fusion process between cellular and subcellular compartments. The biological cell and the subcellular structures in the form of vesicles are modelled by an arrangement of two concentric spheres corresponding to the inner and outer layer of the membrane bounding the vesicles. The analysis shows eight succeeding topological stages of membrane transformations during the fusion process and these stages are characterized. It is concluded that there is a vectorial translocation of lipid molecules from the outer layers of the membranes before the fusion process to the internal layer of the membrane bounding the vesicle after the fusion process and there is no lipid translocation in the reverse direction. 相似文献
56.
Fruit developmental regulation of the kiwifruit actinidin promoter is conserved in transgenic petunia plants 总被引:5,自引:0,他引:5
We have examined the expression of actinidin, a cysteine protease found in kiwifruit, over the course of fruit development. Protease activity was first seen in fruit that had reached about half their final weight, and rose to high levels at harvest. The 5-flanking region (nucleotides –1301 to +58) of a kiwifruit actinidin gene was fused to the -glucuronidase (GUS)-coding region, and the chimaeric gene was introduced into transgenic petunia plants. Induction of the GUS gene was observed during the later stages of seed pod development, closely resembling the pattern of actinidin induction in fruit tissues of kiwifruit. Some GUS expression was also detected in the vascular system of the receptacle, leaves, stems and roots. A shorter promoter fragment consisting of nucleotides –115 to +58 conferred similar spatial and temporal regulation in some of the transgenic plants. 相似文献
57.
AProteinExtractedfromMouseSpermThatPlaysanImportantRoleinFertilizationZHUANGDa-zhong;(庄大中),ZHANGTian-yin(张天荫),CHENDa-yuan;(陈大... 相似文献
58.
观察了hFPIL6/2对6.5Gyγ线照射NIH小鼠第10天造血功能恢复的影响。结果表明:照射小鼠连续4d给予hFPIL6/2250μg·kg-1·d-1,其脾重、CFU-8、骨髓有核细胞数及CM-CFU分别比对照组增加59.0%、278.5%、57.9%和138.2%,统计学处理均有显著差异;对此四项指标的改善也明显优于25μg组。另外,250μg剂量组小鼠外周血象30d的动态观察结果表明,hFPIL6/2不但能明显提高红细胞和血红蛋白的最低值,而且能使血小板的恢复提前。提示hFPIL6/2在促进血小板生成和促进红系造血方面可能具有良好的应用前景。 相似文献
59.
乙肝前S2(HBVPreS2)肽段由55个氨基酸组成,其N端肽段含Th和B细胞抗原决定簇。我们将化学合成的PreS2epitope(120-145)基因与HBcAg基因不同位点进行融合,融合基因在大肠杆菌中获得表达,并对融合蛋白进行了纯化。经ELISA和Western-blot实验表明,融合蛋白具有PreS2和HBcAg两者的抗原性。此外,研究还表明,强启动子能使表达水平有一定提高。 相似文献
60.
SPA::EcoRI fusion protein was produced by Escherichia coli JM103 carrying the multicopy expression plasmid pMTC48, the multicopy repressor plasmid pRK248, and the multicopy protection plasmid pEcoR4 in a 60-L working volume airlift tower loop reactor on M9 minimal medium with glucose. Cell mass concentration, total cell count, number of colony-forming units, specific growth rate, yield coefficient, and metabolite (acetate, pyruvate, succinate, lactate, ethanol) concentrations were monitored during the growth phase and gene expression. Gene expression was induced by temperature shift or chemically by isopropyl-thiogalactosidase in the airlift tower loop reactor (ALTR) at constant cultivation time and in a small stirred tank reactor at different cultivation times. During induction, the cultivation medium was supplemented with concentrated Luria-Bertani (LB) medium. The intracellular enzyme activity was evaluated as a function of the time after the start of the induction. It was found that the reduction of the glucose concentration and increase of the dissolved oxygen concentration reduced the acetate produced and increased the intracellular enzyme activity. (c) 1993 John Wiley & Sons, Inc. 相似文献