Research groups such as Okinawa Institute of Science and Technology Graduate University have succeeded for the first time in the world in capturing and observing images of the moment when coral cells that coexist with phytoplankton called "zooxanthellae" take up zooxanthellae. Was announced.


Coral bleaching has become a problem in Okinawa and other areas where the water temperature rises and zooxanthellae escape and become white, and it is expected to be a clue to elucidate the mechanism of bleaching in the future.

Coral takes in a type of phytoplankton, "zooxanthellae," and instead of providing a safe haven, "zooxanthellae" receive the nutrients produced by photosynthesis, creating a "symbiotic relationship."



A research group at Okinawa Institute of Science and Technology Graduate University and Kochi University has developed a technology for culturing coral cells called Usuedamidoriishi, and will take a picture of the moment when the cells cultivated in the experimental container take up zooxanthellae. Announced that it was the first successful in the world.



From the video, it is observed that coral cells with a length of about 0.03 mm extend long finger-like protrusions called pseudopodia, attach to zooxanthellae with a diameter of about 0.01 mm, and swallow for about 30 minutes. It's done.



Regarding coral, the "bleaching phenomenon" in which the water temperature rises in Okinawa and other areas causes zooxanthellae to escape and become white has become a problem, and this research is expected to be a clue to elucidate the mechanism of bleaching in the future.



Professor Noriyuki Sato of Okinawa Institute of Science and Technology Graduate University said, "In order to conserve and regenerate coral reefs, it is necessary to understand the symbiotic relationship between coral and zooxanthellae, and I think that research will accelerate." I am.

Symbiosis of coral and zooxanthellae Unknown reality revealed

The results of this research have revealed a number of unknown facts about the symbiosis of coral and zooxanthellae.



A type of phytoplankton, zooxanthellae, usually floats in the ocean in two forms, a sphere and a flagella that swim around, but these two types are placed in the same container as the coral cells. As a result, the coral did not look at the swimming cells, but approached and took up only the spherical cells.



It was assumed that the zooxanthellae, which are moving around vigorously, jump into the cells of the coral, but the coral side actively captures and takes in the zooxanthellae floating in the sea. It turned out that it can be seen.



There was also an interesting discovery from the observation of zooxanthellae after it was taken up by coral cells.

When zooxanthellae are observed for a few days after being taken up, they are divided into those that are decomposed into pieces and broken, and those that are surrounded by a membrane in coral cells, and only those that are surrounded are in a symbiotic relationship. Was built.



The research group said that the disintegration was originally thought to be a remnant of the zooxanthellae being eaten by the corals, and during evolution, the corals preyed on the zooxanthellae. It is believed that they have come to be regarded as a companion who nourishes by photosynthesis and have built a symbiotic relationship.



The research group of Okinawa Institute of Science and Technology Graduate University has succeeded in deciphering all the genetic information and genomes of the coral and zooxanthellae studied this time, and based on this discovery, which coral We will continue to elucidate whether genes are working to take in and keep zooxanthellae alive.



Professor Noriyuki Sato, who has been studying the development and evolution of living things for more than 50 years, said, "When I saw the images of coral cells taking up zooxanthellae, it was like dreaming. My research life It was the most moving event of all. "