Nobuhiko Nakashima / Professor / Division of Biosciences
Department of Integrated Biosciences / / Insect Virology (RNA viruses)

Career Summary
1988: Graduated, Faculty of Agriculture, Kyushu University
1991: Research Scientist, National Institute of Sericultural and Entomological Science
1996: Doctor of Agriculture from Kyushu University
2001: Senior Research Scientist, National Institute of Agrobiological Sciences
2011: Head of Insect-Microbe Research Unit, National Institute of Agrobiological Sciences
2011: Associate Professor, The University of Tokyo (Concurrent Position)
2013: Professor, The University of Tokyo (Concurrent Position)
Educational Activities
Graduate school: Applied Bioresource Sciences
Research Activities
Characterization of viruses in Hemiptera (1996-2000)
We described two new RNA viruses. The positive stranded RNA genome of these viruses contains an internal ribosome entry site (IRES) at the intergenic region (IGR). The IGR-IRES mediated initiation of translation does not use Met-tRMAi. These viruses have been classified into a new family, called Dicistroviridae.
Mechanism of IGR-IRES mediated initiation of translation (2001-2010)
We discovered that IGR-IRES is composed of four stem-loop structures containing three pseudoknots. This RNA tertiary structure was essential for binding with ribosome in the absence of eukaryotic translation initiation factors. Using a cross-link analysis of RNA, we identified rpS25 on 40S ribosome as the ligand protein of the IGR-IRES.
1) Nakashima, N. and Uchiumi, T. (2009) Functional analysis of structural motifs in dicistroviruses. Virus Research 139: 137-147.
2) Nishiyama, T., Yamamoto, H., Uchiumi, T., and Nakashima, N. (2007) Eukaryotic ribosomal protein RPS25 interacts with the conserved loop region in a dicistroviral intergenic internal ribosome entry site. Nucleic Acids Research 35: 1514-1521.
3) Sasaki, J. and Nakashima, N. (2000) Methionine-independent initiation of translation of the capsid protein in an insect RNA virus. Proceedings of the National Academy of Science, USA. 97: 1512-1515.
Other Activities
The Japanese Society of Applied Entomology and Zoology
The Japanese Society for Virology
The RNA Society of Japan
The Molecular Biology Society of Japan
American Society for Virology
Dicistroviridae Study group, International Committee for Taxonomy of Viruses
Future Plan
Insects in Hemiptera are an important vector of plant viruses. However, interaction between vector insects and plant viruses is largely unknown. We intend to reveal these interactions to prevent virus transmission by insects.
Messages to Students
There are no agro-chemicals to prevent virus diseases in crops. This is why pesticides are necessary for the stable production of crops. The problem here is that insects develop a resistance to pesticides. Our goal is to develop a strategy to fight viral diseases in plants, which are transmitted by insect vectors. Vector insects are small and research tools for them are limited, so this is a challenging endeavor. We welcome graduate students who have a strong will to reach our goal together.