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
Objective: To screen and analyze key express sequence tags (ESTs) which were differentially displayed in every period of SD rats' primary hepatic carcinoma and reveal the molecular mechanism of carcinogenesis. Met...Objective: To screen and analyze key express sequence tags (ESTs) which were differentially displayed in every period of SD rats' primary hepatic carcinoma and reveal the molecular mechanism of carcinogenesis. Methods: Using diethylnitrosamine (DENA) as a cancerigenic agent, animal models with different phases of primary hepatic cancer were constructed in SD rats. Rats were respectively sacrificed at d 14, d 28, d 56, d 77, d 105 and d 112 after the rats received DENA by gavage, then the livers were harvested. One part of the livers was classified according to their pathological changes, while the other was reserved for molecular mechanism studies on hepatocarcinogenesis. The differentially expressed genes were isolated from both normal and morbid tissues by mRNA differential display technique (DDRT-PCR). After the fragments were sequenced, bioinformatics were .used to analyze the results. Results: Twelve differentially expressed cDNA fragments were obtained. Nine fragments had the homology with known cDNA clones, especially EST-7 was similar to BN/SsNHsdMCW mitochondrion gene and the identity was 100% which suggested EST-7 may be the part of BN/SsNHsdMCW mitochondrion gene. In contrast, other three fragments (EST-1, EST-3 and EST-5) had extremely low identity to any genes registered in GENBANK databases. Conclusions: BN/SsNHsdMCW mitochondrion gene was expressed in different periods of hepatocarcinogenesis. Moreover, EST-I, EST-3 and EST-5 were suggested to contribute to the development of rat hepatocarcinogenesis, and thus may be candidates of new targets of oncogenes or cancer suppressor genes.展开更多
The present study established a rat model of chronic cerebral ischemia using bilateral common carotid artery permanent ligation to analyze cytochrome C oxidase activity and mRNA expression in hippocampal mitochondria....The present study established a rat model of chronic cerebral ischemia using bilateral common carotid artery permanent ligation to analyze cytochrome C oxidase activity and mRNA expression in hippocampal mitochondria. Results showed significantly decreased cytochrome C oxidase activity and cytochrome C oxidase II mRNA expression with prolonged ischemia time. Further analysis revealed five mitochondrial cytochrome C oxidase II gene mutations, two newly generated mutations, and four absent mutational sites at 1 month after cerebral ischemia, as well as three mitochondrial cytochrome C oxidase III gene mutations, including two newly generating mutations, and one disappeared mutational site at 1 month after cerebral ischemia. Results demonstrated that decreased cytochrome C oxidase gene expression and mutations, as well as decreased cytochrome C oxidase activity, resulting in energy dysmetabolism, which has been shown to be involved in the DatholoQical Process of ischemic brain iniurv.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.
基金supported by the Key Program for Science and Technology Development of Henan Province [122102310174]the Zoology Key Subject of Henan Province
文摘Objective: To screen and analyze key express sequence tags (ESTs) which were differentially displayed in every period of SD rats' primary hepatic carcinoma and reveal the molecular mechanism of carcinogenesis. Methods: Using diethylnitrosamine (DENA) as a cancerigenic agent, animal models with different phases of primary hepatic cancer were constructed in SD rats. Rats were respectively sacrificed at d 14, d 28, d 56, d 77, d 105 and d 112 after the rats received DENA by gavage, then the livers were harvested. One part of the livers was classified according to their pathological changes, while the other was reserved for molecular mechanism studies on hepatocarcinogenesis. The differentially expressed genes were isolated from both normal and morbid tissues by mRNA differential display technique (DDRT-PCR). After the fragments were sequenced, bioinformatics were .used to analyze the results. Results: Twelve differentially expressed cDNA fragments were obtained. Nine fragments had the homology with known cDNA clones, especially EST-7 was similar to BN/SsNHsdMCW mitochondrion gene and the identity was 100% which suggested EST-7 may be the part of BN/SsNHsdMCW mitochondrion gene. In contrast, other three fragments (EST-1, EST-3 and EST-5) had extremely low identity to any genes registered in GENBANK databases. Conclusions: BN/SsNHsdMCW mitochondrion gene was expressed in different periods of hepatocarcinogenesis. Moreover, EST-I, EST-3 and EST-5 were suggested to contribute to the development of rat hepatocarcinogenesis, and thus may be candidates of new targets of oncogenes or cancer suppressor genes.
文摘综述了有关线粒体基因组 (m t DNA)多态性与运动能力的研究 :mt DNA为 16 5 6 9bp的双链闭环分子 ,含有 37个基因 ,排列紧密 ,无内含子。其转录、复制受核 DNA调控 ,同时也不同程度地影响核 DNA表达 ;mt DNA的多样性很高的结论被进一步证实 ,且 m t DNA的差异主要分布在群体内的个体间 ,而群体间的差异较小 ;目前研究认为 ,m t DNA多态性可能造成群体中有氧代谢能力的个体差异 ,是决定有氧能力和训练敏感性的可能分子机制之一。展示了中国运动员和汉人 m t DNA HVR 多态性 ,及其与运动能力关联性研究的结果 ,并对比分析了限制性酶切、直接测序、活细胞培养等方法对 mt DNA多态性与运动能力的研究结果 ,发现众多研究结果还存在不少争议 ,仍需进一步深入研究。 m t DNA作为良好的遗传标记 ,对其单核苷酸多态性(SNP)的分析及其与运动能力表型的关联研究和分子遗传学探讨具有重要意义和研究前景。
基金the International Cooperation Program of Science and Technology Department of Jilin Province, No. 20100751
文摘The present study established a rat model of chronic cerebral ischemia using bilateral common carotid artery permanent ligation to analyze cytochrome C oxidase activity and mRNA expression in hippocampal mitochondria. Results showed significantly decreased cytochrome C oxidase activity and cytochrome C oxidase II mRNA expression with prolonged ischemia time. Further analysis revealed five mitochondrial cytochrome C oxidase II gene mutations, two newly generated mutations, and four absent mutational sites at 1 month after cerebral ischemia, as well as three mitochondrial cytochrome C oxidase III gene mutations, including two newly generating mutations, and one disappeared mutational site at 1 month after cerebral ischemia. Results demonstrated that decreased cytochrome C oxidase gene expression and mutations, as well as decreased cytochrome C oxidase activity, resulting in energy dysmetabolism, which has been shown to be involved in the DatholoQical Process of ischemic brain iniurv.