Saitou’s research interests are broad: from history of modern humans to origin of life. His recent publications can be classified into two major fields: (1) genetic history of Japonesians and Negritos, (2) genome analysis of evolutionarily conserved non-coding sequences. After 2-year JSPS postdoc in Tokyo, he served assistant professor at Department of Anthropology, Faculty of Science, University of Tokyo during 1989-1991. He then moved to National Institute of Genetics as associate professor at Division of Evolutionary Genetics. In 2002, he was promoted to professor at Division of Population Genetics (current position). He also has joint appointments at Department of Genetics, Graduate University for Advanced Studies and Department of Biological Sciences, University of Tokyo
Evolutionary history and roles of conserved non-coding sequences in eukaryotes
A considerable region of eukaryote genomes is noncoding. Most of them are junk DNA and do not have functions. If we find evolutionary conservation, however, these conserved regions should have some function through purifying selection. From the initial stage of molecular evolutionary studies, protein noncoding regions were suspected to be involved in gene regulation. Now it is becoming clear that at least some noncoding regions play important roles in gene regulation. The functional elements are expected to evolve more slowly than surrounding nonfunctional DNA, as they are under purifying selection. Therefore, conserved noncoding sequences (CNSs) are likely to be important from the functional point of view.
Verterate CNSs were discovered by comparison of human and fugu fish genome sequences. CNS analyses have been proved to be powerful for detecting regulatory elements.
CNEs (conserved noncoding elements) were found through comparison of human, mouse, and rat genomes. Conserved noncoding DNA sequences are now found from diverse eukaryote organisms, from plants, invertebrates, and vertebrates, by comparing closely related species genomes. I will discuss our recent studies on conserved noncoding sequences.