In many organisms, the difference in codon usage patterns among genes reflects variation in local base compositional biases and the intensity of natural selection. In this study, a comparative analysis was performed t...In many organisms, the difference in codon usage patterns among genes reflects variation in local base compositional biases and the intensity of natural selection. In this study, a comparative analysis was performed to investigate the characteristics of codon bias and factors in shaping the codon usage patterns among mitochondrion, chloroplast and nuclear genes in common wheat （Triticum aestivum L.）. GC contents in nuclear genes were higher than that in mitochondrion and chloroplast genes. The neutrality and correspondence analyses indicated that the codon usage in nuclear genes would be a result of relative strong mutational bias, while the codon usage patterns of mitochondrion and chloroplast genes were more conserved in GC content and influenced by translation level. The Parity Rule 2 （PR2） plot analysis showed that pyrimidines were used more frequently than purines at the third codon position in the three genomes. In addition, using a new alterative strategy, 11, 12, and 24 triplets were defined as preferred codons in the mitochondrion, chloroplast and nuclear genes, respectively. These findings suggested that the mitochondrion, chloroplast and nuclear genes shared particularly different features of codon usage and evolutionary constraints.展开更多
2017年10月18日,Science Translational Medicine发布题为"Aristolochic acids and their derivatives are widely implicated in liver cancers in Taiwan and throughout Asia"的研究论文,该文指出含马兜铃酸的草药可通过...2017年10月18日,Science Translational Medicine发布题为"Aristolochic acids and their derivatives are widely implicated in liver cancers in Taiwan and throughout Asia"的研究论文,该文指出含马兜铃酸的草药可通过诱导特异性的"马兜铃酸突变指纹"诱发肝癌,并建议公众避免摄入含有马兜铃酸的草药。我国自2000年始,针对含马兜铃酸的中草药,国家食品药品监督管理总局(CFDA)陆续取消了关木通、广防己和青木香等的药用标准,并通知加强相关药物监管;《中国药典》中也逐渐取消一系列相关中草药的记载。此文发表后,国家中医药管理局快速启动了关于马兜铃酸的"毒性"问题研讨会,与会专家对国内外关于马兜铃酸的毒性研究进行了充分讨论,发现暴露史、致癌剂量和潜伏期不明确,乙肝等关键影响因素未纳入分析,样本量小、混杂因素多,证据链不完整,数据间巨大差异缺少解析,基础研究论据不足等是目前研究存在的主要问题。为了正确认识马兜铃酸的毒性和致癌风险、指导临床安全合理用药,专家们提出如下建议:(1)尽快完善马兜铃酸致癌性的系统评价,科学阐明马兜铃酸与肝癌发生的关系;(2)制定含马兜铃酸类药物安全用药风险警示,进一步加大监管力度;(3)深化中药毒性的临床研究,逐步明确所有中药的临床不良反应。展开更多
基金Supported by the Sate Key Basic Research and Development Plan of China （2003CB715904） and the National Science Foundation for 0verseas Distinguished Young Scholar （30428003）
文摘In many organisms, the difference in codon usage patterns among genes reflects variation in local base compositional biases and the intensity of natural selection. In this study, a comparative analysis was performed to investigate the characteristics of codon bias and factors in shaping the codon usage patterns among mitochondrion, chloroplast and nuclear genes in common wheat （Triticum aestivum L.）. GC contents in nuclear genes were higher than that in mitochondrion and chloroplast genes. The neutrality and correspondence analyses indicated that the codon usage in nuclear genes would be a result of relative strong mutational bias, while the codon usage patterns of mitochondrion and chloroplast genes were more conserved in GC content and influenced by translation level. The Parity Rule 2 （PR2） plot analysis showed that pyrimidines were used more frequently than purines at the third codon position in the three genomes. In addition, using a new alterative strategy, 11, 12, and 24 triplets were defined as preferred codons in the mitochondrion, chloroplast and nuclear genes, respectively. These findings suggested that the mitochondrion, chloroplast and nuclear genes shared particularly different features of codon usage and evolutionary constraints.
文摘2017年10月18日,Science Translational Medicine发布题为"Aristolochic acids and their derivatives are widely implicated in liver cancers in Taiwan and throughout Asia"的研究论文,该文指出含马兜铃酸的草药可通过诱导特异性的"马兜铃酸突变指纹"诱发肝癌,并建议公众避免摄入含有马兜铃酸的草药。我国自2000年始,针对含马兜铃酸的中草药,国家食品药品监督管理总局(CFDA)陆续取消了关木通、广防己和青木香等的药用标准,并通知加强相关药物监管;《中国药典》中也逐渐取消一系列相关中草药的记载。此文发表后,国家中医药管理局快速启动了关于马兜铃酸的"毒性"问题研讨会,与会专家对国内外关于马兜铃酸的毒性研究进行了充分讨论,发现暴露史、致癌剂量和潜伏期不明确,乙肝等关键影响因素未纳入分析,样本量小、混杂因素多,证据链不完整,数据间巨大差异缺少解析,基础研究论据不足等是目前研究存在的主要问题。为了正确认识马兜铃酸的毒性和致癌风险、指导临床安全合理用药,专家们提出如下建议:(1)尽快完善马兜铃酸致癌性的系统评价,科学阐明马兜铃酸与肝癌发生的关系;(2)制定含马兜铃酸类药物安全用药风险警示,进一步加大监管力度;(3)深化中药毒性的临床研究,逐步明确所有中药的临床不良反应。
