|Affiliation||Department of Applied chemistry and Life Science|
|Concurrent post||Research Center for Agrotechnology and Biotechnology|
|Fields of Research||Molecular Genetics / Molecular Biology / Functional Genomics|
|Degree||PhD in Pharmaceutical Sciences (The University of Tokyo)|
|Academic Societies||The Molecular Biology Society of Japan / The Pharmaceutical Society of Japan / The Japanese Biochemical Society / The Genetic Society of America|
Please append ".tut.ac.jp" to the end of the address above.
|Researcher information URL（researchmap）||Researcher information|
A number of chemicals or wastes are continuously produced by our social activities and are accumulated in the environment as well as in our bodies. These substances may be potentially and unexpectedly changed into genotoxic reagents, causing DNA damage to lead to regulatory dysfunctions of genetic information. Furthermore, it has been well known that excess DNA damage often shortens human lifespan mainly due to an increased risk of various cancers. The problem of "genome environment" is important in ecological life sciences as well as medical sciences. In addition, development of chemical sensing and environmental assessment technologies are in progress. So far, three research subjects have been carried out using model organisms S. cerevisiae and C. elegans by molecular, biochemical and genetic approaches. :
(1) Identification and characterization of novel nematode helicase-related proteins including DRH-3 that play roles in maintenance of genome integrity,
(2) Development of yeast-based assay systems for detecting genotoxicity and chemicals, and
(3) Analysis of soil nematodes by the DNA barcoding and development of C. elegans lifespan-based assay for ecotoxicants.
Theme1：Studies on a novel RNAi gene drh-3 involved in maintenance of genome integrity in C. elegans
We identified a novel nematode gene drh-3 that functions in both maintenance of chromosome integrity and RNA interference (RNAi). Since the relationship between RNAi and chromosome regulations has been largely unknown, we have focused on functional analyses of DRH-3 protein in C. elegans. This study will contribute to progress in basic biomedical sciences.
Selected publications and works
◆Toshihiko Eki., Takeshi Ishihara, Isao Katsura, and Fumio Hanaoka: A genome-wide survey and systematic RNAi-based characterization of helicase-like genes in Caenorhabditis elegans. DNA Res., 14(4), 183-199 (2007)
◆Masaharu Nakamura, Rumi Ando, Taro Nakazawa, Takuro Yudazono, Naoko Tsutsumi, Naoki Hatanaka, Toshiyasu Ohgake, Fumio Hanaoka, Toshihiko Eki: Dicer-related drh-3 gene functions in germ line development by maintenance of chromosomal integrity in Caenorhabditis elegans. Genes Cells, 12(9), 997-1010 (2007)◆Toshihiko Eki and Fumio Hanaoka: Discovery of orphan helicases and deorphanization by genome-wide analyses in two model organisms, S. cerevisiae and C. elegans, Bacterial DNA, DNA polymerase and DNA Helicases. pp.411-432, Nova Science Publishers (2010)
◆Taishi Kobayashi, Takuro Murakami, Yuu Hirose, and Toshihiko Eki: Purification and characterization of double-stranded nucleic acid-dependent ATPase activities of tagged Dicer-related helicase 1 and its short isoform in Caenorhabditis elegans. Genes, 11(7), 734 (2020)
Theme2：Development of genetically altered yeasts by synthetic biological approach
It is important to detect genome toxicities of chemicals and waste products. We have developed the biosensing assays by recombinant reporter yeasts for detecting genotoxicity. We also tried to develop recombinant yeasts for sensitive detection of genotoxicity by using the CRISPR/Cas9-mediated genome editing technology.
Selected publications and works
◆Kohei Ichikawa and Toshihiko Eki: A novel yeast-based reporter assay system for the sensitive detection of genotoxic agents mediated by a DNA damage-inducible LexA-GAL4 protein. The Journal of Biochemistry (Tokyo), 139(1), 105-112 (2006)
◆Yukari Ochi, Harumi Sugawara, Mio Iwami, Megumi Tanaka and Toshihiko Eki: Sensitive detection of chemical-induced genotoxicity by the Cypridina secretory luciferase reporter assay using DNA repair-deficient strains of Saccharomyces cerevisiae. Yeast, 35(1), 265-278 (2011)
◆Hajime Suzuki, Takahiro Sakabe, Yuu Hirose, and Toshihiko Eki: Development and evaluation of yeast-based GFP and luciferase reporter assays for chemical-induced genotoxicity and oxidative damage. Applied Microbiology and Biotechnology, 101(2), 659-671 (2017)
◆Toshihiko Eki: Yeast-based genotoxicity tests for assessing DNA alterations and DNA stress responses: a 40-year overview. Applied Microbiology and Biotechnology, 102(6), 2493-2507 (2018)
Theme3：DNA metabarcode analysis of soil organisms for assessment of soil environment
We are developing novel DNA barcoding technique of soil organisms, especially soil nematodes using the next-generation sequencer for evaluating soil environment. We developed a novel lifespan-based assay for detecting biotoxicity of materials. This test will be useful for risk management of wasted chemicals because nematodes including C. elegans are majority of the living organisms in soil.
Selected publications and works
◆Hiroaki Harada, Masaru Kurauchi, Rie Hayashi, and Toshihiko Eki: Shortened lifespan of nematode Caenorhabditis elegans after prolonged exposure to heavy metals and detergents. Ecotoxicol. Environ. Saf., 66(3), 378-383 (2007)
◆Masaru Kurauchi, Hisashi Morise, and Toshihiko Eki: Using the nematode Caenorhabditis elegans daf-16 mutant to assess the lifespan toxicity of prolonged exposure to ecotoxic agents. J. Health Sci., 55(5), 796-804 (2009)
◆Toshihiko Eki:Ecotoxicology of free-living nematode Caenorhabiditis elegans, Ecotoxicology Around the Grobe, pp.1-52, Nova Science Publishers (2011)
◆Hisashi Morise, Erika Miyazaki, Shoko Yoshimitsu, and Toshihiko Eki: Profiling nematode communities in unmanaged flowerbed and agricultural field soils in Japan by DNA barcode sequencing. PLoS One, 7(12), e51785 (10 pages) (2012)
◆Harutaro Kenmotsu, Kiichi Uchida, Yuu Hirose, and Toshihiko Eki: Taxonomic profiling of individual nematodes isolated from copse soils using deep amplicon sequencing of four distinct regions of the 18S ribosomal RNA gene. PLoS ONE, 15(10), e0240336 (31 pages) (2020)
◆Harutaro Kenmotsu, Masahiro Ishikawa, Tomokazu Nitta, Yuu Hirose, and Toshihiko Eki: Distinct community structures of soil nematodes from three ecologically different sites revealed by high-throughput amplicon sequencing of four 18S ribosomal RNA gene regions. PLoS ONE, 16(4), e0249571 (31 pages)(2021)
◆Harutaro Kenmotsu, Emi Takabayashi, Akinori Takase, Yuu Hirose, and Toshihiko Eki: Use of universal primers for the 18S ribosomal RNA gene and whole soil DNAs to reveal the taxonomic structures of soil nematodes by high-throughput amplicon sequencing. PLoS ONE, 16(11), e0259842 (31 pages)(2021)