| 题名 | 酵母基因组进化中一些重要新性状的产生及其效应 |
| 作者 | 江会锋 |
| 学位类别 | 博士 |
| 答辩日期 | 2008-06 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 王文 |
| 关键词 | 线粒体 功能限制放松 全基因组重复 真核多细胞生物起源 密码子使用偏好 |
| 其他题名 | Evolution of genetic novelties and their effects in yeast genomes |
| 学位专业 | 动物学 |
| 中文摘要 | 本论文用生物信息学的方法对酵母基因组进化中产生的新性状进行了系统深入的研究。首先，在大多数的真核生物中，线粒体是生物能量生成所必需的细胞器。但当葡萄糖的含量丰富的时候，即使是在有氧条件下，经过基因组重复（WGD，whole genome duplication）后的大多酵母也都可以不需要线粒体而执行发酵过程，而且甚至在线粒体基因组缺陷的情况下仍可以生存。在本次研究中，我们揭示核编码的线粒体相关基因的进化速率在基因组重复后的物种中比其在基因组重复前的物种中显著加快。而且这些基因的密码子使用偏好也在基因组重复后的物种中减弱。密码子使用偏好的模式和一个特殊转录调控因子的分布显示在基因组重复后的进化支系中，有效的有氧发酵过程的起源时间大致是在Kluyveromyces polysporus 和 Saccharomyces castellii 从它们的共同祖先分化之后。根据上述结果我们得出结论，可能正是这种新的能量策略的产生导致了线粒体相关基因的功能在基因组重复后的物种中选择性放松。 其次，我们系统地研究了一个多细胞真菌Ashbya gossypii 和九个单细胞酵母之间密码子使用偏好性的差异。细胞周期调控基因一直被认为是它们形态差异的关键基因。由于A. gossypii 和典型的单细胞酵母Saccharomyces cerevisiae 有几乎完全一样的细胞周期调控基因，因此形态上的差异可能是由于直系同源基因的表达调控差异造成的。我们发现在A. gossypii 中细胞周期基因的翻译效率比在其他单细胞酵母中显著增高，同时也发现单细胞酵母中的新陈代谢基因比其在A.gossypii 中有显著增高的翻译效率。因为基因的翻译效率和该基因在物种中的重要性密切相关，所以我们观察到的这些基因翻译效率的显著差异可能可以阐明A. gossypii 和单细胞酵母的形态差异的原因。同时我们的结果对理解真核生物多细胞的起源过程也有提示意义。 |
| 英文摘要 | In this thesis, we extensively and systematically studied evolution patterns of newtraits in yeast genomes by bioinformatics methods. Mitochondria are essential forcellular energy production in most eukaryotic organisms. However, even whenglucose is abundant yeast species that underwent whole genome duplication (WGD)mostly conduct fermentation even under aerobic conditions and most can survive without a functional mitochondrial genome. In this study we show that evolutionary rate for the nuclear-encoded mitochondrial genes were greater in post-WGD speciesthan pre-WGD species. Furthermore, codon usage bias was relaxed for these genes in post-WGD yeast species. The codon usage pattern and the distribution of a particular transcription regulatory element suggest that the change to an efficient aerobic fermentation lifestyle in this lineage might have emerged after WGD between the divergence of Kluyveromyces polysporus and Saccharomyces castellii from their common ancestor. This new energy production strategy could have led to the relaxation of mitochondrial function in the relevant yeast species. Second, the emergence of multicellular organisms was one of the most profound developmental transitions in the history of life. The filamentous fungus Ashbya gossypii grows into multicellular mycelium which is distinct from its closely related unicellular yeast species. It has been proposed that genes functioning during cell cycle play central roles for such phenotypic differences. Because A. gossypii shares an almost identical set of cell cycle genes with the typical yeast Saccharomyces cerevisiae, the divergences might occur at the regulation level for orthologous genes. Here we show that cell cycle genes have significantly higher translation efficiency in A. gossypii than their orthologous genes in yeasts. Meanwhile, genes which have significantly higher translation efficiency in yeasts are enriched with metabolic functions. Because translation efficiency of a gene is closely related with its functional importance, the observed functional distributions of orthologous genes with different translation efficiency might account, at least partially, for the phenotypic differentiation between A. gossypii and the yeast species. |
| 语种 | 中文 |
| 公开日期 | 2010-10-14 |
| 内容类型 | 学位论文 |
| 源URL | [http://159.226.149.42:8088/handle/152453/6089]  |
| 专题 | 昆明动物研究所_基因起源组 |
| 推荐引用方式 GB/T 7714 | 江会锋. 酵母基因组进化中一些重要新性状的产生及其效应[D]. 北京. 中国科学院研究生院. 2008. |
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