Biohistory journal, Winter, 2006

     Insects, birds, fish... When I was a primary school student, I raised many living creatures. Even today I enjoy the tropical fish in my laboratory.

     The mainstream of developmental biology studies how individuality is acquired when the single cell that results from fertilization divides. I also wanted to solve this riddle, and when I was a graduate student, I had the idea to remove a homogenous cluster of lens cells from the lens of an eye to use as a model for cell differentiation. I was allowed to work at the new laboratory started by Prof. Tokindo Okada. I was happy to be a part of such an excellent environment, but I couldn't seem to make any headway on my research.
     Not only the crystalline lenses, but all the tissue I took from the bodies of animals were in tight adherence. When I separated them and placed them in a culture dish, they would adhere to the bottom of the dish as they expanded. This adhesion phenomenon had been known for some time, and it was also known that calcium and magnesium ions were involved. No one knew the mechanism, however. I noticed that depending on the conditions of cultivation, the speed at which the cells adhered to the bottom of the dish changed. I then became more interested in adhesion rather than differentiation. This is a secondary stream in developmental biology research, but Prof. Okada supported me.
     Eventually, this led to the discovery of the adhesion molecule "cadherin", whose operation is dependent on the calcium ion. The bodies of animals are created as the cells are linked through the cadherin protein of the cell membrane. I thought this was a secondary field, but in fact it focuses on an important aspect of the development phenomenon. You never know what research will lead to.
     The discovery of cadherin-that's it in essence, but I think there was significance in turning the adhesion phenomenon into an exact science, and asking individual questions that arose while observing the cells. Is the adhesion of the cells the same phenomenon as the adhesion at the bottom of a culture dish? Do magnesium and calcium play the same role? Because I enjoyed observing living creatures, my senses may have become more refined. I always say to young people that the most important thing is to conduct research by finding what it is you like the best.
Text: Atsushi Yamagishi

     Observing the cells that were involved with the discovery of cadherin.
     In the presence of calcium, the clustered cells tightly adhere to each other (left). The adhesion weakens without calcium (right).

     After the international seminar in Finland, I went for a drive on the lakeshore with Prof. Okada and his wife.

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