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Comparative Analysis of Gene Expression in Camera Eye and its Implication to Genomic Diversification of Bilateria
https://ir.soken.ac.jp/records/981
https://ir.soken.ac.jp/records/981366fc7c0-5274-45eb-986e-0e457f0ac428
| 名前 / ファイル | ライセンス | アクション |
|---|---|---|
要旨・審査要旨 / Abstract, Screening Result (283.3 kB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||
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| 公開日 | 2010-02-22 | |||||
| タイトル | ||||||
| タイトル | Comparative Analysis of Gene Expression in Camera Eye and its Implication to Genomic Diversification of Bilateria | |||||
| タイトル | ||||||
| タイトル | Comparative Analysis of Gene Expression in Camera Eye and its Implication to Genomic Diversification of Bilateria | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_46ec | |||||
| 資源タイプ | thesis | |||||
| 著者名 |
小倉, 淳
× 小倉, 淳 |
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| フリガナ |
オグラ, アツシ
× オグラ, アツシ |
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| 著者 |
OGURA, Atsushi
× OGURA, Atsushi |
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| 学位授与機関 | ||||||
| 学位授与機関名 | 総合研究大学院大学 | |||||
| 学位名 | ||||||
| 学位名 | 博士（理学） | |||||
| 学位記番号 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 総研大甲第681号 | |||||
| 研究科 | ||||||
| 値 | 生命科学研究科 | |||||
| 専攻 | ||||||
| 値 | 18 遺伝学専攻 | |||||
| 学位授与年月日 | ||||||
| 学位授与年月日 | 2003-03-24 | |||||
| 学位授与年度 | ||||||
| 値 | 2002 | |||||
| 要旨 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | It has been extremely difficult to study the molecular evolution of bilaterian animals that consist of Protostomes and Deuterostomes, because none of complete genome sequences were known for any bilaterian animals until a decade years ago. However, the advancement of the genome sequencing has changed this situation completely. Not only the genomic sequences but also the gene expression data have been obtained for various kinds of bilaterian organisms such as fly, nematode, ascidian, fish, rat, mouse and human. Thus, I conducted the present study for the purpose of studying the evolutionary process of bilaterian animals and the mechanisms of species diversity through the vast number of genomic data and gene expression data.<br /> In chapter 1, l gave the overview of species diversity and evolution of bilaterian animals. In particular, I focused on the evolutionary diversification of organs such as eyes. In chapter 2, I then developed a novel method for estimating the ancestral gene set using all the available genome sequences and gene expression data.<br /> In chapter 3, to understand the molecular mechanism of species divergence, I focused upon the camera eye structures that were known to be very similar because of "convergent evolution". In fact, because human and octopus belong to Deuterostomes and Protostomes, respectively, the camera eye, the one of the most elaborate eye, evolved the camera eye independently after their speciation, which is well known as a typical example of the convergent evolution in the level of morphology. Then, l conducted the comparative analysis of gene expression in the camera eyes between human and octopus. In practice, I collected the gene expression data of octopus eye using EST sequencing, and compared these EST sequences with the complete genome sequences of nematode, fly and human as well as the gene expression data of human eye. As a result, I found that 729 genes were expressed commonly between the camera eyes of human and octopus. Applying my method to the estimation of the ancestral gene set, I found that 933 genes had already existed at the common ancestor of Protostomes and Deuterostomes. I also found that 886 out of 933 genes were conserved between human and octopus although nematode and fly are closely related to octopus than to human. This suggests that the conservation of the ancestral gene set of camera eye is required for the evolution of the camera eye even after the speciation of human and octopus, implying that the evolution of the camera eyes of human and octopus is not subjected to the convergent evolution, but rather the divergent evolution derived from the common ancestor.<br /> In chapter 4, to understand the process of bilaterian evolution, I conducted the evolutionary analysis of bilaterian animals. The animals belonging to bilaterian phyla had started sudden species diversification in only 5 to 10 million years from 530 million years ago. This sudden diversification is inscribed in the fossil records such as Burgess Shale and called "Cambrian explosion". The molecular mechanism of this "Cambrian explosion" is studied by many researchers using commonly conserved genes such as 18S rRNA. However, taking into account that species evolved by the changing the usage or conservation of gene set as shown in chapter 3, it is reasonable that we study the molecular mechanism of this phenomena using all the available data including the genomic sequences. For the study of the evolution of the bilaterian animals, l estimated the ancestral gene set of common bilaterian ancestor to be 6,577 gene clusters. Then, I studied how this ancestral gene set had been maintained since the split of plant-animal-fungus at 1,070 million years ago, and also how it has changed to the extant animals through the Cambrian explosion. As a result, I found the number of gene clusters belonging to the ancestral gene set of bilateria had emerged from 2,469 gene clusters to 6,577 gene clusters. Comparing these gene clusters to the genome of fungi and plants, I found that fungi have had been conserved much more gene clusters in the extant fungi rather than plants have. This observation indicates that fungi are closely related to bilaterian animals than plants. Moreover, I found that the extant bilaterian animals might tend to maintain the ancestral gene set and differentiate their function instead of to emerge novel genes. I observed many events of gene loss in the genome of nematode, fly, mouse, human, suggesting that gene loss events may have an important role in the evolution since the pre-Cambrian period.<br /> Finally, in chapter 5, l described the conclusion of the present study. Here, l conclude that the events of gene loss and the differentiation of usage of gene set may have an important role for the species diversity and organ diversity in the bilaterian evolution. | |||||
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| 値 | 有 | |||||
