| Research Abstract |
In this research project, from the viewpoint of evolutionary genetics we attempted to elucidate biodiversity that living organisms have acquired through evolution since the beginning of 3.5 billion years ago. Currently, a lot of complete genome sequences from a variety of species such as human are available, and hundreds of genome-sequencing projects are thought to be underway. Thus, these genomes gave us an opportunity to initiate the project of biodiversity analysis.
In the first academic year we conducted detection of duplicated regions in eukaryotic genomes such as human. In order to improve the accuracy of the detection, we developed a new statistical method of finding significant duplicated regions. Consequently, we successfully identified 74 duplicated regions in human, 59 in yeast, and 197 in worm. We constructed a database for these results, so that anyone can access our data through Internet by using a graphical user interface. The times of duplication events were estimated so as to study what the duplication affect to evolution.
In the second academic year, in order to analyze the MHC region of human in detail, a large DNA sequence (〜400 kb) in the region was newly determined. As a result, we found large genome duplication, and reconstructed the evolutionary process of the duplication. Moreover, high nucleotide diversity was found in non-coding regions, implying that hitchhiking effects might have occurred in the regions. Next, we extended our study to microbes, and could reveal that in general bacterial genome structures are quite unstable even in operons that are believed to be functionally important units. In addition, we developed a new method for the detection of evolutionary direction of GC-content change, which leads to high diversity of genomes.
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