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Two Drosophila heteroneura males fighting for a female. (Squeeze the window to make it visible at the right bottom corner.)
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Koichiro Tamura, PhD
Director, Researh Center for Genomics and Bioinformatics
Professor, Department of Biological Sciences
Tokyo Metropolitan University

Contact Information
1-1 Minami-osawa, Hachioji
Tokyo 192-0397, Japan
phone: +81-42-677-3128
email: ktamura@tmu.ac.jp

Research Interests
  1. Adaptative evolution of a tropical fruit fly species to temperate climate
    The distribution of Drosophila albomicans was limited in tropics in Southeast Asia until the mid-1980. Since then, however, the distribution has been extended toward the north to west Japan to date. In our study, we found that the cold tolerance of this species has been improved in the Japanese population with a higher response to cold acclimation. This suggests that improved cold tolerance is attributable to gene expression changes in response to the cold acclimation. Using RNA-seq method, we found many candidate genes responsible for the improvement of cold tolerance. We are trying to identify the causative genes among these genes by artificially modifying gene expression using the GAL4/UAS system in D. melanogaster. [Ref. 1]
  2. Genetic mechanisms of neo-sex chromosome evolution in a fruit fly species
    karyotypes
    Drosophila albomicans has giant X and Y chromosomes named neo-X and neo-Y chromosomes, which originated by fusions of the canonical X and Y chromosomes, respectively, and autosomes corresponding to the third chromosomes in its sister species, D. nasuta. As a result, a large part of the genome has become meiotic-recombination-free. What is the merit of these neo-sex chromosomes? This is a mystery as the meiotic recombination is believed to be evolutionarily advantageous. We are studying to solve this issue. [Ref. 2]
  3. Theoretical study for molecular evolution and molecular phylogenetics
    Evolutionary changes of genomic DNA sequences are an ultimate driving force of organismal evolutions. Therefore, it is important to study how DNA sequences change during the evolutionary period for a deep understanding of the evolution of genomes and organisms as well as performing accurate inferring phylogenetic trees and estimating divergence times. We are studying the molecular evolution of genes and genomes, using mathematical modeling, computer simulations, and real data analyses. A special focus is on developing methods for molecular evolutionary and phylogenetic analyses. The current project is to estimate divergence times in a phylogenetic tree in case of unequal evolutionary rates among lineages. [Ref. 3][Ref. 4] Reltime
    The phylogenetic tree of zinc finger protein genes from human and mouse, showing extreme evolutionary rate heterogeneity among genes and lineages (A), is successfully time-aligned by the RelTime method (B). x1: human ZFX, x2: mouse ZFX, y1: human ZFY, y2: mouse ZFY.
  4. Development of Molecular Evolutionary Genetics Analyses software
    With its theoretical basis firmly established in molecular evolutionary and population genetics, the comparative DNA and protein sequence analyses play a central role in reconstructing the evolutionary histories of species and multigene families, estimating rates of molecular evolution, and inferring the nature and extent of selective forces shaping the evolution of genes and genomes. As a response to the demand for easy-to-use computer programs for such analyses, we have produced Molecular Evolutionary Genetics Analysis (MEGA) software, with its focus on facilitating the exploration and analysis of DNA and protein sequence variations from an evolutionary perspective. [Ref. 5] MEGAX
  5. Bioinformatics for Drosophila species identification
    The identification of Drosophila species requires high expertise and thus not an easy practice for ordinary researchers. To facilitate this task, we took a bioinformatics approach, focusing on the pattern of wing vein, which is one of the important key characters in traditional taxonomy. Measuring the distances between crossing points of wing veins, we succeeded to identify each species from sixteen Drosophila species commonly observed around Tokyo area. [Ref. 6][Web app.] DrosoWing

Recent Publications
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