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Shigeyuki Kawano / Professor / Division of Integrated Biosciences
Department of Integrated Biosciences / / Flower development and the Y chromosome of the dioecious plant, Silene latifolia.Uniparental inheritance of mtDNA and cpDNA in the isogamous green alga, Ulva compressa.Chloroplast division and FtsZ in the micro-algae, Cyanophora paradoxa and Nannochloris bacillaris
http://park.itc.u-tokyo.ac.jp/pls/index.html

Career Summary

1977: Graduated, Faculty of Sciences, Okayama University

1978-87: Technician and Research Associate, National Institute for Basic Biology

1985: Researcher dispatched by MEXT, The University of Sheffield, UK

1982: Doctor of Science from Tokyo Metropolitan University

1988: Research Associate, The University of Tokyo

1991: Associate Professor, The University of Tokyo

1998: Professor, The University of Tokyo

Educational Activities

Graduate School: Origin of Eukaryotic Life Systems

Undergraduate School: Flower development, Origin of Sex

Research Activities
1) Homeotic genes exclusively expressed in male and female flowers of the dioecious plan Silene latifolia: S. latifolia is a dioecious plant in which sex is determined by heteromorphic X and Y chromosomes. The Y chromosome controls the floral sexual differentiation via stamen promoting function and gynoecium suppressing function. However, the genes directly controlling the floral sexual differentiation remain unknown. Through our research, we are identifying some homeotic genes encoded in the sex chromosomes of S. latifolia.

2) Asymmetry of eyespot and mating structure positions in Ulva compressa: In the past, plasmogamy of green algae was categorized solely by the relative sizes of gametes produced by two mating types (+ and ). Recently, however, locations of cell fusion sites and/or mating structures of gametes have been found to differ between mating types in several green algae (asymmetry of cell fusion site and/or mating structure positions). To use this asymmetry for determining gamete mating type, we are exploring a new method (FE-SEM) for visualizing the mating structure of U. compressa.

Literature

1) Yamamoto, M., Nishikawa, T., Kajitani, H. and Kawano, S.: Patterns of asecual reproduction in Nannochloris bacillaris and Marvania geminate (Chlorophyta, Trebouxiophyceae). Planta, 226, 917-927 (2007).
2) Koizumi, A., Amanai, Y., Ishii, K., Nishihara, K., Kazama, Y., Uchida, W., and Kawano, S.: Floral development of an asexual and female-like mutant carrying two deletions in gynoecium-suppressing and stamen-promoting functional regions on the Y Chromosome of the dioecious plant Silene latifolia. Plant Cell Physiol. 48, 1450-1461 (2007).
3) Sato, M., Nishikawa, T., Kajitani, H. and Kawano, S.: Conserved relationship between FtsZ and peptidoglycan in the cyanelles of Cyanophora paradoxa similar to that in bacterial cell division. Planta, 227, 177-187 (2007).

Other Activities

Associate Member of the Science Council of Japan (SCJ)

Botanical Society of Japan (BSJ)

Genetic Society of Japan (GSJ)

Japanese Society of Plant Physiologists (JSPP)

Japanese Society of Plant Morphology (JAPM)

Editor in Chief of Cytologia

Associate Editor of Physarum News Letter

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Future Plan
1) We have now identified another strong candidate gene for sexual differentiation in plants. Because all of these genes are located on autosomes, a sex-determining gene on the Y chromosome would be expected to directly or indirectly control their expression. The characterization of these sex-chromosome `master' genes would therefore greatly contribute to our knowledge of sex-differentiation in dioecious plant flowers.

2) Ulva compressa is at an intermediate stage of sexual differentiation between isogamy and anisogamy. Gametes of U. compressa may germinate parthenogenetically and develop into dioecious gametophytic thalli. We are using separate clones of mating type + and mating type gametophytes, respectively. Association of mating structure with flagellar roots is also examined by serial sectioning and three-dimensional reconstruction.

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