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101.
Cell-surface expression of a membrane-anchored form of the human chorionic gonadotropin alpha subunit 总被引:15,自引:0,他引:15
We carried out experiments designed to generate a novel cell-surface protein from a small glycosylated secretory protein. DNA encoding the entire precursor of human chorionic gonadotropin (hCG, alpha subunit) was fused precisely to DNA encoding the transmembrane and cytoplasmic domains of the vesicular stomatitis virus glycoprotein. When expressed in animal cells this DNA encoded the 92-amino acid hCG-alpha subunit anchored in cellular membranes by an extension composed of the 49 carboxyl-terminal amino acids of vesicular stomatitis virus glycoprotein. This hybrid protein was transported efficiently to the plasma membrane of animal cells. The two asparagine-linked glycans on the anchored form of hCG-alpha were large and heterogeneous when compared to those on the secretory form. Experiments employing in vitro mutagenesis and the glycosylation inhibitor tunicamycin established that the presence of at least one of the two asparagine-linked glycans was required for expression of the anchored molecule on the cell surface. However, as reported previously, secretion of hCG-alpha occurred in the absence of glycosylation. Also, mutations eliminating the second glycosylation site (at amino acid 78) in both the anchored or secreted forms apparently led to partial denaturation or a conformational change interfering with transport of the protein. 相似文献
102.
Yanyi Liu Michael Clark Qifeng Zhang Danmei Yu Dawei Liu Jun Liu Guozhong Cao 《Liver Transplantation》2011,1(2):194-202
Nanostructured V2O5 thin films have been prepared by means of cathodic deposition from an aqueous solution made from V2O5 and H2O2 directly on fluorine‐doped tin oxide coated (FTO) glasses followed by annealing at 500°C in air, and studied as film electrodes for lithium ion batteries. XPS results show that the as‐deposited films contained 15% V4+, however after annealing all the vanadium is oxidized to V5+. The crystallinity, surface morphology, and microstructures of the films have been investigated by means of XRD, SEM, and AFM. The V2O5 thin film electrodes show excellent electrochemical properties as cathodes for lithium ion intercalation: a high initial discharge capacity of 402 mA h g?1 and 240 mA h g?1 is retained after over 200 cycles with a discharging rate of 200 mA g?1 (1.3 C). The specific energy density is calculated as 900 W h kg?1 for the 1st cycle and 723 W h kg?1 for the 180th cycle when the films are tested at 200 mA g?1 (1.3 C). When discharge/charge is carried out at a high current density of 10.5 A g?1 (70 C), the thin film electrodes retain a good discharge capacity of 120 mA h g?1, and the specific power density is over 28 kW kg?1. 相似文献
103.
黄土丘陵区旱地作物水分生态适应性系统评价 总被引:8,自引:1,他引:8
根据调查资料和田间试验结果,系统地分析了旱地不同作物生长发育与降水分布的时序关系、旱地作物水分潜在利用率和旱地主要作物水分供需平衡与错位特征,并利用水分生态适应性数学模型,对宁南黄土丘陵区主要作物的水分生态适应性进行了定量评价.结果表明,秋熟作物生长发育与降水分布耦合性较好,夏熟作物生长发育与降水分布耦合性较差.不同作物的降水潜在利用率存在差异。其基本规律是:多年生牧草>薯类作物>谷类作物;秋熟作物>夏熟作物.作物的水分满足率和生态适应性,秋熟作物优于夏熟作物,丰水年份优于干旱年份.旱地6种主要作物的水分生态适应性指数排序依次为:谷子>马铃薯>糜子>胡麻>豌豆>春小麦. 相似文献
104.
A new system for selection of transformed Aspergillus foetidus was reported. In this system, TK- A. foetidus which were constructed by homologous recombination of mutated TK gene of vaccinia virus with TK gene of A. foetidus were screened by adding BUdR in agar plates. Conditions for screen of TK+ A. foetidus strain, transformation of A. foetidus and selection of transformed TK- A. foetidus have been studied. By using this system, several transformed A. foetidus which contained HBsAg gene derived bf a promoter H8 cloned from genomic DNA of A. foetidus were isolated. It was demonstrated that HBsAg gene was integrated into the chromosome DNA of A. foetidus by Southern blot after many passages of spores. ELISA showed that HBsAg was positive in the growth medium (p/n = 20). The 22 nm particles which were very similar to the HBsAg particles in human serum were found in the growth medium by immunoelectromicroscope. Western blot also gave the specific bands. All these data showed that HBsAg gene was expressed in A. foetidus and the products were secreted into the growth medium. The selection system using TK gene as marker could generally be used to study the expression of foreign gene in A. foetidus. 相似文献
105.
Rump LV Strain EA Cao G Allard MW Fischer M Brown EW Gonzalez-Escalona N 《Journal of bacteriology》2011,193(8):2058-2059
Enterohemorrhagic Escherichia coli (EHEC) of serotype O157:H7 has been implicated in food-borne illnesses worldwide. An evolutionary model was proposed in which the highly pathogenic EHEC O157:H7 serotype arose from its ancestor, enteropathogenic E. coli (EPEC) O55:H7 (sorbitol fermenting [SOR(+)] and β-glucuronidase positive [GUD(+)]), through sequential gain of virulence, phenotypic traits, and serotype change. Here we report six draft genomes of strains belonging to this evolutionary model: two EPEC O55:H7 (SOR(+) GUD(+)) strains, two nonmotile EHEC O157:H(-) strains (SOR(+) GUD(+)) containing plasmid pSFO157, one EHEC O157:H7 (SOR(-) GUD(+)) strain, and one O157:H7 strain containing plasmid pSFO157 (SOR(+) GUD(+)). 相似文献
106.
B-Cell activating factor (BAFF) is critical for B cell survival and maturation; excessive expression of it corrupts B-cell
tolerance and may lead to autoimmunity. The gene, scFv-Fc, coding for the antibody of BAFF was inserted into the eukaryotic
expression vector, pPICZαA, and transformed into Pichia pastoris. A high-level expression strain was obtained using a ‘yeastern blotting’ method. The scFv-Fc antibody was purified and 56 mg
was obtained from 1 l of culture supernatant. It retained high binding activity to both soluble BAFF and membrane-bound BAFF. 相似文献
107.
The aim of the present study is to investigate the expression of a novel estrogen receptor, G protein-coupled receptor 30 (GPR30) and its correlation with matrix metalloproteinases-9 (MMP-9) in epithelial ovarian cancer (EOC). Ovary tissues were obtained from 39 female patients, including 30 cases of EOC and 9 cases of benign ovarian tumor. Four normal ovary tissues were used as control. Immunohistochemical staining was used to detect the expressions of GPR30 and MMP-9. Chi square test, Fisher's exact test and Spearman's rank correlation analysis were used for statistical analysis. The results showed that GPR30 overexpression rate in EOC cases was significantly higher than those in benign ovarian tumor and normal ovary cases. Whereas MMP-9 overexpression rate in EOC cases was significantly higher than that in normal ovary cases, without any difference to that in benign ovarian tumor cases. To demonstrate the relationship between GPR30 and clinicopathological variables of EOC, we further analyzed the pathology type, FIGO stage and age of patients sampled in our study. The analysis showed there were significant differences of GPR30 overexpression rate among various pathology types and different FIGO stages (P<0.05), and no significant difference of both GPR30 and MMP-9 among three age groups (P>0.05). Moreover, GPR30 expression was positively correlated with MMP-9 (r(s)=1.000, P=0.002). These results suggest that GPR30 may be involved in the invasion and metastasis of EOC, being a potential index of EOC early diagnosis and malignancy grade prediction. 相似文献
108.
109.
110.
丙型肝炎病毒RNA打点杂交检测方法同RT-PCR方法的比较 总被引:1,自引:0,他引:1
采用HCV基因组结构区C区cDNA探针和非结构区NS3-4区cDNA探针,建立了用打点杂交(dotblothybridization)检测血清中HCVRNA的方法,同采用HCV基因组5’端非编码区的一对寡核苷酸引物通过逆转录-聚合酶链式反应(RT-PCR)检测血清中HCVRNA的方法相比较,发现两种方法都能快速早期和特异地检出血清中HCVRNA,但RT-PCR法敏感性优于RNA打点杂交法。对于无血清学指标的慢性NANB肝炎病人的诊断,可采用这两种方法。这两种方法的敏感性在很大程度上依赖于引物和探针的敏感性,以及RNA提取方法。RT-PCR法适用于诊断病毒血症和复制,打点杂交法适用于研究HCVRNA量的变化,对治疗的评价,以及为实验筛选较高滴度的HCVRNA阳性样本。 相似文献