Masataka G. Suzuki / Lecturer / Division of Biosciences
Department of Integrated Biosciences / / Molecular Entomology

Career Summary
1993: Bachelor of Agriculture, Tokyo University of Agriculture and Technology
1995: Master of Agriculture, The University of Tokyo
1998: Doctor of Agriculture, The University of Tokyo
1998-2000: Postdoctoral researcher, The Institute of Physics and Chemical Research (RIKEN)
2000-2002: Research fellow, The Japan Society for the Promotion of Science (JSPS)
2002-2010: Researcher, The Institute of Physics and Chemical Research (RIKEN)
2010: Lecturer, The University of Tokyo

Educational Activities
Graduate school: Insect development and physiology
Undergraduate school: Insect engineering, Exercise for Applied Biological Experiments (Faculty of Agriculture)
Research Activities
We are interested in sexual differentiation because it is an important theme in the field of development. The sex of insects is determined on a cell-by-cell basis. In other words, sex determination in insect cells is not influenced by the surrounding environment. Therefore, we believe that insect cells are a good model system for understanding sex determination. Since sex determination occurs at early embryonic stage, we set out to establish insect cell lines from male and female embryos. For this purpose, we used embryos of the silkworm strain 'Sex-limited black egg' because this strain allows us to identify the sex of embryos based on the color of the egg shells. We have found that a doublesex homolog, Bmdsx, plays an essential role in silkworm sexual development (2, 3). Bmdsx RNA is alternatively spliced in males and females, and as a result, males have the male-specific BmDSX protein and females have the female-specific BmDSX protein. Therefore, we can conclude that regulation of the sex-specific splicing of Bmdsx RNA is very important for sex determination.To explore how the alternative splicing of Bmdsx specifically regulates sex, we used our male and female cell lines to develop an in vivo splicing assay system. As a result, we successfully identified a cis-acting element CE1 and a trans-acting factor BmPSI that regulate sex-specific splicing of Bmdsx RNA (1).Now we are trying to identify factors that interact with BmPSI to elucidate how BmPSI represses inclusion of female-specific Bmdsx exons in a male-specific manner.We are also trying to develop an efficient gene-targeting technique in the silkworm.

(1) Masataka G. Suzuki, Shigeo Imanishi, Naoshi Dohmae, Tomoe Nishimura, Toru Shimada, and Shogo Matsumoto. (2008) Establishment of a novel in vivo sex-specific splicing assay system to identify a trans-acting factor that negatively regulates splicing of Bombyx mori dsx female exons. Molecular and Cellular Biology, 28:333-343.
(2) Masataka G. Suzuki, Shunsuke Funaguma, Toshio Kanda, Toshiki Tamura, and Toru Shimada (2005) Role of the male BmDSX protein in the sexual differentiation of Bombyx mori. Evolution and Development, 7:58-68.
(3) Masataka G. Suzuki, Shunsuke Funaguma, Toshio Kanda, Toshiki Tamura, and Toru Shimada (2003) Analysis of the biological functions of a doublesex homologue in Bombyx mori. Developmental Genes and Evolution, 213:345-354.

Other Activities
The Japanese Society of Sericultural Science (JSSS)
The Molecular Biology Society of Japan (MBSJ)
The Japanese Society of Applied Entomology & Zoology (JSAEZ)
Future Plan
On the basis of the findings for fruit flies and the silkworm, we will elucidate the sex-determining mechanisms of other insects. We also want to verify the unique characteristics of and the similarities between insects and vertebrates. We will attempt to investigate developmental mechanisms of germ cells in insects as closely related to sexual differentiation. In addition, we will focus on the functional characteristics of insects in an attempt to develop new biological resources.

Messages to Students
Insects are the most thriving creatures on Earth. Therefore, insects may have many excellent values as biological resources. In addition, insects may provide clues on how to overcome hurdles in life. I hope that you will master the skills necessary for scientists and learn some skills for everyday life through studying insects.