National University Corporation Kumamoto University
Plankton in freshwater also produces zwitterions, which are the source of the scent of ocean beaches, to prevent freezing.
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・This discovery was made after 10 years of tracking phytoplankton and chemical substances that breed in the ice-covered Lake Baikal in Russia.
– A type of dinoflagellate grows in the gaps between ice crystals and in lake water. It has been discovered that these freshwater plankton store zwitterionic compounds in their cells, which are the source of the scent of seashore. Marine plankton produce this compound to cope with the osmotic pressure of salt water, but this is the first time that its production has been confirmed in freshwater, where there is no need for osmotic pressure regulation.
・Freshwater plankton also have the ability to produce this component, and when breeding in frozen lakes, it is thought that they create this sulfur-containing zwitterion in their cells to prevent freezing. [Summary explanation]
Professor Takashi Toda of Kumamoto University’s Graduate School of Advanced Science (Faculty of Science) and a research group from the Institute of Limnology of the Russian Academy of Sciences conducted field surveys in Lake Baikal for 10 years to determine the
phytoplankton that thrive in the ice-covered lake. discovered that they create zwitterions containing sulfur atoms to prevent freezing. This zwitterion (dimethylsulfoniopropionate: DMSP*4) is known as a compound produced by marine plankton to cope with the osmotic pressure of salt water, and its decomposition product is familiar to the general public as a component of the scent of the seashore. Thing. It is surprising that this compound can be detected in Lake Baikal, where there is no need for osmotic adjustment and the sulfate ions that supply sulfur atoms are only 1/500th that of seawater, and that its concentration is even higher than that of seawater. It turns out that freshwater plankton also have the genetic ability to produce DMSP and use this zwitterion to survive in ice and water at 0°C. The results of this research were published in the scientific journal “Communications Biology” published by Springer Nature on November 25, 2020 (Japan time).
【the next deployment】
DMSP was found to be an important chemical for plankton, which breeds even in freshwater Lake Baikal when it freezes. It is expected that it is an important chemical for survival near the freezing point not only in Lake Baikal, but also in many lakes and marshes in high latitudes, snowy valleys in alpine mountains, and plankton that breed in glaciers. In addition to clarifying the existence of antifreeze functions in various natural environments, laboratory-level research such as quantifying DMSP production factors through culture
experiments is expected. It is also thought that genetic elucidation will be developed to explain why humans have developed such a defense mechanism. This result is related to a wide range of scientific fields, including chemistry, biology, limnology, oceanography, and glaciology, and is expected to lead to a variety of developments. [Paper information]
Paper title: Abundant production of dimethylsulfoniopropionate as a cryoprotectant by freshwater phytoplanktonic dinoflagellates in ice-covered Lake Baikal Authors: Kei Toda, Vladimir Obolkin, Shin-Ichi Ohira, Kentaro Saeki Journal: Communications Biology, 6, no.1194 (2023)doi : 10.1038/s42003-023-05573-9
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[Contact information]
Kumamoto University Graduate School of Advanced Science Research (School of Science)
Person in charge: Professor Takashi Toda
Phone: 096-342-3389
e-mail: todakei*kumamoto-u.ac.jp (Please replace * with @)
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