Graduate School of Frontier Sciences, The University of Tokyo Department of
Integrated Biosciences

Our research interest is how and why phenotypic diversity has evolved and has been maintained in nature. Organisms exhibit great phenotypic variation that may adapt to complex and fluctuating environments. What kinds of developmental, physiological, and neural modifications underlie such diversification? What specific genes have changed to produce the different phenotypes? How many genetic changes have controlled the variation of the traits? What kinds of mutations have occurred in these genes? Do these mutations share any molecular features? Such fundamental questions may help to understand how predictable evolution is.

　One of the crucial steps to address these questions is to identify causative genes and mutations responsible for such variation. Rapid advances in technologies will enable us to find not only the genes and mutations, but also genome structures, epigenetic features, and regulatory networks that may promote or constrain phenotypic diversification. It is also necessary to look into the evolutionary dynamics of the causative genes and mutations in natural ecosystems. Since evolution affects ecosystem functions and vice versa, a mutation with a large ecological effect may change the intensity or direction of selection on the mutation itself. Thus, comprehensive approaches to reveal the dynamics and functions of the genes and mutations underlying phenotypic diversification can further increase the predictability of evolution in nature.

“Enhancing plant power to save the global environment and supplementing animal functions with plant power”

　Plants, which account for 90% of the earth's biomass, support the global environment. We, humans, account for only 0.01%. In order to save the global environment, we are researching the hidden "plant power" of plants, especially their regenerative power and stress tolerance. Plants can live for thousands of years because they can regenerate their organs even when their branches and trunks are cut off by disasters. Plants can withstand environmental stresses that animals would give up. We will contribute to the development of methods for extracting even more plant power by unraveling the secrets of this power from the perspective of epigenetic regulation and live imaging analysis of the way plants live. In addition, understanding the principles underlying the symbiosis between photosynthetic and non-photosynthetic organisms, such as the endosymbiosis between coral symbiotic algae and cnidarians, will lead to the elucidation of how new biological functions emerge. Furthermore, if we can transfer the ability of plants to utilize light energy and fix carbon dioxide to animals, we will be able to power up their functions as well. We are taking on this challenge by using the latest cell engineering and synthetic biology techniques such as cell fusion and nucleic acid synthesis. Let's work together to carry out exciting and stimulating research.

　Graduates of the laboratory are active in jobs such as pharmaceutical development, agricultural research, food and cosmetic development, and bio-optical instrument development.

Our current research topics are as follows.

We create a pluripotent cell mass, callus, from plant organs and regenerate leaves and stems in the laboratory. The regeneration phenomenon involves priming, which prepares for regeneration from the callus stage. In addition, if environmental stress is given to the plant beforehand, its regeneration ability is also enhanced. The mechanisms of memory, regeneration, and stress tolerance in plants will be elucidated through epigenetic regulation.

Chromatin, which consists of DNA and proteins, changes its structure and nuclear arrangement in three dimensions in response to environmental stress. Based on the concept of four-dimensional spatial control with an additional time axis, we analyze chromatin dynamics in the plant nucleus by live imaging. This will allow us to get closer to the "individuality of plant cells" that cannot be found only through sequencing and biochemical analysis.

We will create animal-animal hybrid cells and planimal cells by cell fusion of cultured Chinese hamster cells, which are used for drug production, and human cancer cells, with the primitive red algae with minimal plant genomes. We aim to reproduce evolutionary symbiotic phenomena and to activate plant metabolic circuits in cultured animal cells.

Chloroplasts (plastids) in land plants and algae are thought to have been acquired by eukaryotic ancestors via endosymbiosis, a process incorporating cyanobacterium-like prokaryotes into their cells, but many mysteries remain as to how this process took place. Through the analyses of predation devices capturing prey organisms, photosynthetic antenna devices, and other ‘ancestral’ traits, we will reveal how primitive chloroplasts evolved.

Some cnidarians (e.g. reef-building corals, sea anemones, jellyfish) are known to endosymbiotize a type of dinoflagellate, formerly called zooxanthellae. In addition, many algae and non-photosynthetic organisms form a variety of "photosymbiotic" relationships in various local water environments such as rivers and ponds. We are conducting research to clarify how the mechanisms for maintaining these photosymbiotic systems evolved, and what kinds of environmental responses have driven the diversification of photosymbiotic systems.