Department of Biological Sciences Graduate School of Science The University of Tokyo
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Hisayoshi Nozaki (Associate Professor)
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Research interests

Species taxonomy of eukaryotic algae based on morphology and molecular phylogeny; Origin of male and female as revealed by the comparative studies of the colonial Volvocales; Origin and macro-taxonomy of eukaryotic plants.

We welcome everyone who loves“lower eukaryotes”and is much interested in evolutionary biology.


We have two research objectives using living cultured materials of eukaryotic algae and protozoa. These cultures were basically established by ourselves based on the field-collected samples.  Thus, we welcome field survey and go to everywhere to get interesting organisms. 

One of our objectives is to construct  natural taxonomic systems of species of eukaryotic algae and their relatives based on  comparative morphology and molecular phylogeny.   We have firstly construct a natural taxonomic system of species of eukaryotic algae based on the morphological and monophyletic species concept in the genus Chlorogonium (Nozaki et al. 1998, J. Phycol.).  This taxonomic methodology has been applied to various green microalgae and the charalean genus Nitella (Sakayama et al. 2005, J. Phycol.). 

The other is to resolve fundamental biological problems such as origin of male-female sexuality and origin and macro-taxonomy of eukaryotic plants.   Recently, we have  firstly demonstrated the evolutionary link between the dominant isogametic mating type (minus) and the “male” by determining the male-specific gene “OTOKOGI” (PlestMID) in the anisogamous volvocalean Pleodorina starrii (Nozaki et al. 2006, Curr. Biol.).  This breakthrough provides an opportunity to address any number of extremely interesting questions regarding evolution of oogamy and the origins of male-female dichotomy. 

Based on the genome sequence data of the primitive red alga Cyanidioschyzon (e. g. Nozaki et al. 2007, BMC Biol.), we resolved the nonmonophyly of the primary photosynthetic eukaryotes (Archaeplastida) and proposed a new taxonomic concept of plants, Plantae emend. Nozaki et al. (2003, J. Mol. Evol.) or “Super” Plant Kingdom.  Although the recent multiple nuclear gene analyses using more than 100 nuclear genes demonstrated strong monophyly of the three groups of primary photosynthetic eukaryotes, our re-examination of such a data matrix using wider taxon sampling and slowly evolving nuclear genes showed the robust non-monophyly of Archaeplastida (Nozaki et al. 2007, Mol. Biol. Evol.).  We believe that the phylogenetic relationships of orgaisms must be single.

Lab members

Postdoctoral fellows: Hiroko KAWAI-TOYOOKA, Yuko MOGI

Graduate students: Yi YANG, Kaoru KAWAFUNE, Ryo MATSUZAKI, Nanako ISAKA, Rei MORI, Yoko ARAGAKI, Toshiyuki TAKAHASHI

Undergraduates: Rintato HIRAIDE

Guest Postdoctoral fellow: Masahiro SUZUKI (Toyo University)

Selected publications

Nozaki, H., Ohta, N., Morita, E. & Watanabe, M. M. 1998. Toward a natural system of species in Chlorogonium (Volvocales, Chlorophyta): a combined analysis of morphological and rbcL gene sequence data J. Phycol. 34: 1024-1037.

Nozaki, H., Misawa, K., Kajita, T., Kato, M., Nohara, S. and Watanabe, M. M. 2000. Origin and evolution of the colonial Volvocales (Chlorophyceae) as inferred from multiple, chloroplast gene sequences. Mol. Phylog. Evol. 17: 256-268.

Nozaki, H., Mori, T., Misumi, O., Matsunaga, S. and Kuroiwa, T. 2006. Males evolved from the dominant isogametic mating type. Curr. Biol. 16: R1018-R1020.

Nozaki, H., Takano, H., Misumi, O., Terasawa, K., Matuzaki, M., Maruyama, S., Nishida, K., Yagisawa, F., Yoshida, Y., Fujiwara, T., Takio, S., Tamura, K., Chung, S.-J., Nakamura, S., Kuroiwa, H., Tanaka, K., Sato, N. and Kuroiwa, T. 2007. A 100%-complete sequence reveals unusually simple genomic features in the hot spring red alga Cyanidioschyzon merolae. BMC Biology 5: 28.

Nozaki, H., Iseki, M., Hasegawa, M., Misawa, K., Nakada, T., Sasaki, N. and Watanabe, M. 2007. Phylogeny of primary photosynthetic eukaryotes as deduced from slowly evolving nuclear genes. Mol. Biol. Evol. 24: 1592-1595.

Ferris, P., Olson, B. J. S. C., De Hoff, P. L., Douglass, S., Casero Diaz-Cano, D., Prochnik, S., Geng, S., Rai, R., Grimwood, J., Schmutz, J., Nishii, I., Hamaji, T., Nozaki, H., Pellegrini, M., and Umen, J. G. 2010. Evolution of an expanded sex determining region in Volvox. Science 328: 351-354.

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Department of Biological Science, Graduate School of Science,The University of Tokyo