Kyushu University Academic Staff Educational and Research Activities Database
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Yoshitaka Kobayakawa Last modified date:2019.05.29

Professor / Division for Experimental Natural Science
Division for Experimental Natural Science
Faculty of Arts and Science

Graduate School
Undergraduate School

Academic Degree
Doctorate of Science
Country of degree conferring institution (Overseas)
Field of Specialization
Zoology, Evolutional Biology, Developmental Biology
Total Priod of education and research career in the foreign country
Research Interests
  • Symbiosis between Hydra and green algae
    keyword : Green Hydra, Chlorella, Brown Hydra, Chlorococcum, Symbiosis, molecular phylogeny
  • Molecular phylogeny of Hydra
    keyword : Hydra, molecular phylogeny
  • Gametogenesis in Hydra
    keyword : Hydra, gametogenesis, specific gene expression
  • Pattern formation in Hydra
    keyword : Hydra, pattern formation, epithelium, nerve, specific gene expression
Academic Activities
1. Ryo Miyokawa, Takuya Tsuda, Hiroyuki J Kanaya, Junko Kusumi, Hidenori Tachida, Yoshitaka Kobayakawa, Horizontal Transmission of Symbiotic Green Algae Between Hydra Strains, Biological Bulletin, 10.1086/699705, 235, 2, 113-122, 2018.10, Some hydra strains belonging to the vulgaris group show a symbiotic relationship with green algae Chlorococcum sp. The symbiotic green algae can escape from the host polyps and can form swimming zoospores (which have two flagella) in culture solution. We observed that co-culture with the symbiotic polyps caused horizontal transmission of the symbionts into some non-symbiotic hydra strains that have no symbionts in nature and that belong not only to the vulgaris group but also to other hydra species groups. Although most of the horizontal transmission has ended in transient symbioses, a newly formed symbiosis between the symbiotic Chlorococcum sp. and strain 105 of Hydra vulgaris (Hydra magnipapillata) has been sustained for more than five years and has caused morphological and behavioral changes in the host polyps. We named this strain 105G. The asexual proliferation rate by budding increased under light conditions, although the feeding activity decreased and the polyp size was reduced in strain 105G. This new symbiosis between Chlorococcum sp. and strain 105G of H. vulgaris provides us with an intriguing research system for investigating the origin of symbiosis..
2. Hitomi Kawaida, Kohki Ohba, Yuhki Koutake, Hiroshi Shimizu, Hidenori Tachida, Yoshitaka Kobayakawa, Symbiosis between hydra and chlorella: Molecular phylogenetic analysis and experimental study provide insight into its origin and evolution, Molecular Phylogeny and Evolution,, 66, 906-914, 2013.02, Although many physiological studies have been reported on the symbiosis between hydra and green algae, very little information from a molecular phylogenetic aspect of symbiosis is available. In order to understand the origin and evolution of symbiosis between the two organisms, we compared the phy- logenetic relationships among symbiotic green algae with the phylogenetic relationships among host hydra strains. To do so, we reconstructed molecular phylogenetic trees of several strains of symbiotic chlorella harbored in the endodermal epithelial cells of viridissima group hydra strains and investigated their congruence with the molecular phylogenetic trees of the host hydra strains. To examine the species specificity between the host and the symbiont with respect to the genetic distance, we also tried to intro- duce chlorella strains into two aposymbiotic strains of viridissima group hydra in which symbiotic chlo- rella had been eliminated in advance. We discussed the origin and history of symbiosis between hydra and green algae based on the analysis..
3. Hitomi Kawaida, Hiroshi Shimizu, Toshitaka Fujisawa, Hidenori Tachida, Yoshitaka Kobayakawa, Molecular phylogenetic study in genus Hydra, Gene, 10.1016/j.gene.2010.08.002, 468, 30-40, 2010.08.
4. Amimoto Y., Kodama R., Kobayakawa Y., Foot formation in Hydra: A novel gene, anklet, is involved in basal disk formation., Mechanisms of Development, 123, 352-361., 2006.01.
5. Kobayakawa Y & Kodama R., Foot formation in Hydra: Commitment of the basal disk cells in the lower peduncle., Develop. Growth Differ, 44, 6, 517-526, 44,517-526, 2002.12.
6. Nagano T., Ito Y., Tashiro K., Kobayakawa Y. & Sakai M., Dorsal induction from dorsal vegetal cells in Xenopus occurs after mid-blastula transution., Mechanisms of Development, 10.1016/S0925-4773(00)00251-3, 93, 1-2, 3-14, 93,3-14, 2000.01.
Membership in Academic Society
  • Japan Scientist Association
Other Educational Activities
  • 2018.08.
Professional and Outreach Activities
not applicable.