Press Releases

DATE2021.11.18 #Press Releases

Shiawasemo defends against strong light without running away from it.

Disclaimer: machine translated by DeepL which may contain errors.

~Discovery of a survival strategy of the 4-cell green alga Shiawasemo that differs from that of closely related algae.

Tokyo Institute of Technology

Graduate School of Science, The University of Tokyo

Hosei University


A research group led by a graduate student, Sho Tanno (at the time of the research) from the School of Bioscience and Biotechnology, School of Bioscience and Biotechnology, Tokyo Institute of Technology, Associate Professor Kenichi Wakabayashi from the Department of Chemistry and Biotechnology, Institute for the Creation of Science and Technology, Associate Professor Hisayoshi Nozaki from the Graduate School of Science, The University of Tokyo and Professor Noriko Ueki from the Hosei University Center for Natural Sciences have discovered that the multicellular green alga Tetrabaena (also known as "shearwaters") has a survival strategy different from that of related green algae in response to strong light stimuli. Tetrabaena (Japanese name: Shiawasemo), a multicellular green alga with only four cells, has been shown to have a different survival strategy in response to strong light stimuli than closely related green algae.

Tetrabaena is an algae that swims in water using cilia and belongs to the order Volvox, the class of green algae. Light is an important energy source for photosynthetic organisms such as green algae, but too much light poses a threat.

The research group has previously shown that Chlamydomonas and Volvox, algae belonging to the order Volvox of the Chlorophyta, exhibit phototaxis and phototremorism by ciliary movements in response to light stimuli. In the present study, when the tetrabayanas were exposed to similar light stimuli, they surprisingly lost their photoreceptor function and did not exhibit light-responsive behaviors. On the other hand, they found that the tetrabaeana had a very high ability to discard excessively strong light energy as heat. It is thought that the tetrabaeina has survived in nature by losing its ability for photoreactive behavior during multicellular evolution, but gaining high photoprotective ability instead.

The results were published online in PLOS ONE on October 26.

Figure: Chlamydomonas and Tetrabaeana (Japanese name: Shiawasemo) phototaxis test experiment. Each culture was placed in a petridish and irradiated from the right side with green light, to which photoreceptors at the eye point respond well. Chlamydomonas showed positive phototaxis and gathered to the right side, but Tetrabaena did not. modified from DOI: 10.1371/journal.pone.0259138.

For more information, please visit the Tokyo Institute of Technology website.