The relationship between the codon usage bias, gene expression level and the AUG context(from -20 to +6 positions relative to the initiator AUG codon) was examined in 541unigene sequences of rice. A significant correl...The relationship between the codon usage bias, gene expression level and the AUG context(from -20 to +6 positions relative to the initiator AUG codon) was examined in 541unigene sequences of rice. A significant correlation for CAI values (codon adaptationindex) was observed at five nucleotide positions (-19, -18, -9, -4, +5), eight (-19, -18,-14, -9, -6, -4, -1, +5) for CPP (codon preference parameter), and seven (-18, -16, -15,-9, -7, -1, +6) for mRNA abundance in the flanking sequence of the initiator AUG codonrespectively, but a significantly positive correlation for both CAI and CPP at twopositions (-4 and +5), indicating that both those positions are evolutionally under thenatural selection constraint at the translational level. By site-directed mutagenesis atseven specific positions (-18, -16, -15, -9, -7, -1 and +6) for allergenic protein thathad the highest mRNA abundance in this study, its expression level decreased dramatically63.3 and 72.5% respectively, indicating the importance of those 7 positions for geneexpression. A highly positive correlation (r=0.625, P<0.01) between AUGCAI and GCcontent in the flanking sequence of the initiator AUG codon showed a more effectivehigher GC content on translation initiation efficiency. The strong preference for G orC at those 8 positions (-6, -5, -3, -2, -1, +4, +5 and +6) in the AUG context suggestedthat an important factor in modulation of the translation efficiency, as well assynonymous codon usage bias, particularly in highly expressed genes.展开更多
基于青岛市菜鸟驿站和含快递服务的中国邮政站点的兴趣点(point of interest,POI)数据,综合运用核密度估计、标准差椭圆、平均最近邻分析、缓冲区分析、相关性分析和主成分分析等方法,解析青岛市快递自提点的空间分布特征及影响因素。...基于青岛市菜鸟驿站和含快递服务的中国邮政站点的兴趣点(point of interest,POI)数据,综合运用核密度估计、标准差椭圆、平均最近邻分析、缓冲区分析、相关性分析和主成分分析等方法,解析青岛市快递自提点的空间分布特征及影响因素。研究结果表明:快递自提点空间分布不均衡,菜鸟驿站的站点分布比中国邮政更集中,集聚效应更明显;菜鸟驿站分布向东北-西南方向延伸,中国邮政站点呈南-北分布,密度均由内向外递减;经济、交通、人口和用地类型等是青岛市快递自提点空间分布差异的主要影响因素;从主成分分析的综合得分来看,黄岛区得分最高,快递自提点的布局较完善,城阳区、平度市、李沧区、崂山区和莱西市的综合得分小于0,快递自提站点布局存在较大改进空间。展开更多
目的:研究Ras蛋白激活物类似物-1基因(Ras protein activator like-1,RASAL1)在正常胃黏膜上皮细胞、胃癌细胞株中的表达情况及其生物学意义。方法:采用RT-PCR和Western blot分别检测高分化胃腺癌细胞株MKN-28、中分化胃腺癌细胞株SGC-7...目的:研究Ras蛋白激活物类似物-1基因(Ras protein activator like-1,RASAL1)在正常胃黏膜上皮细胞、胃癌细胞株中的表达情况及其生物学意义。方法:采用RT-PCR和Western blot分别检测高分化胃腺癌细胞株MKN-28、中分化胃腺癌细胞株SGC-7901、低分化胃腺癌细胞株BGC-823和正常胃黏膜上皮细胞株GES-1中RASAL1基因在mRNA水平和蛋白水平的表达,应用基因测序法检测上述3种胃癌细胞株中K-Ras基因第一外显子第12密码子点突变情况,并分析其意义。结果:RT-PCR和Westernblot检测结果显示,与正常胃黏膜上皮细胞相比,在3种不同分化胃腺癌细胞株中,RASAL1基因的表达在mRNA水平和蛋白水平均下调(P<0.05),分化程度越低表达下调越明显;测序结果表明3种胃腺癌细胞株中均未发现K-Ras基因第一外显子第12密码子点突变。结论:RASAL1基因在含野生型K-Ras的胃癌细胞中呈低表达状态,其表达水平与胃癌的恶性程度有一定的关系。展开更多
基金This work was supported by the National Natural Science Foundation of China(39870421)the Key Research Project of Zhejiang Province,China(2003C22007).
文摘The relationship between the codon usage bias, gene expression level and the AUG context(from -20 to +6 positions relative to the initiator AUG codon) was examined in 541unigene sequences of rice. A significant correlation for CAI values (codon adaptationindex) was observed at five nucleotide positions (-19, -18, -9, -4, +5), eight (-19, -18,-14, -9, -6, -4, -1, +5) for CPP (codon preference parameter), and seven (-18, -16, -15,-9, -7, -1, +6) for mRNA abundance in the flanking sequence of the initiator AUG codonrespectively, but a significantly positive correlation for both CAI and CPP at twopositions (-4 and +5), indicating that both those positions are evolutionally under thenatural selection constraint at the translational level. By site-directed mutagenesis atseven specific positions (-18, -16, -15, -9, -7, -1 and +6) for allergenic protein thathad the highest mRNA abundance in this study, its expression level decreased dramatically63.3 and 72.5% respectively, indicating the importance of those 7 positions for geneexpression. A highly positive correlation (r=0.625, P<0.01) between AUGCAI and GCcontent in the flanking sequence of the initiator AUG codon showed a more effectivehigher GC content on translation initiation efficiency. The strong preference for G orC at those 8 positions (-6, -5, -3, -2, -1, +4, +5 and +6) in the AUG context suggestedthat an important factor in modulation of the translation efficiency, as well assynonymous codon usage bias, particularly in highly expressed genes.
文摘基于青岛市菜鸟驿站和含快递服务的中国邮政站点的兴趣点(point of interest,POI)数据,综合运用核密度估计、标准差椭圆、平均最近邻分析、缓冲区分析、相关性分析和主成分分析等方法,解析青岛市快递自提点的空间分布特征及影响因素。研究结果表明:快递自提点空间分布不均衡,菜鸟驿站的站点分布比中国邮政更集中,集聚效应更明显;菜鸟驿站分布向东北-西南方向延伸,中国邮政站点呈南-北分布,密度均由内向外递减;经济、交通、人口和用地类型等是青岛市快递自提点空间分布差异的主要影响因素;从主成分分析的综合得分来看,黄岛区得分最高,快递自提点的布局较完善,城阳区、平度市、李沧区、崂山区和莱西市的综合得分小于0,快递自提站点布局存在较大改进空间。
文摘目的:研究Ras蛋白激活物类似物-1基因(Ras protein activator like-1,RASAL1)在正常胃黏膜上皮细胞、胃癌细胞株中的表达情况及其生物学意义。方法:采用RT-PCR和Western blot分别检测高分化胃腺癌细胞株MKN-28、中分化胃腺癌细胞株SGC-7901、低分化胃腺癌细胞株BGC-823和正常胃黏膜上皮细胞株GES-1中RASAL1基因在mRNA水平和蛋白水平的表达,应用基因测序法检测上述3种胃癌细胞株中K-Ras基因第一外显子第12密码子点突变情况,并分析其意义。结果:RT-PCR和Westernblot检测结果显示,与正常胃黏膜上皮细胞相比,在3种不同分化胃腺癌细胞株中,RASAL1基因的表达在mRNA水平和蛋白水平均下调(P<0.05),分化程度越低表达下调越明显;测序结果表明3种胃腺癌细胞株中均未发现K-Ras基因第一外显子第12密码子点突变。结论:RASAL1基因在含野生型K-Ras的胃癌细胞中呈低表达状态,其表达水平与胃癌的恶性程度有一定的关系。
