- Associate Professor Kazuharu Arakawa
Introduction of the discussion
The Tardigrade, which is called “the strongest organism on the ground” because of its outstandingly high environmental resistance, has four pairs of limbs lacking joints and proliferates by parthenogenesis.
The land-bearing Tardigrade shifts to a non-metabolic state called cryptobiosis when water runs out of the environment, and the body’s water drops to less than 3%, but it can survive even in this extremely dry environment. This indicates that the land-bearing Tardigrade has a “system” that can survive without losing its biological function even if it loses water.
It has been confirmed so as that the Tardigrade in cryptobiosis is resistant to various environmental stresses, such as ultra-low temperature (273 degrees Celsius below the freezing point of water), ultra-high pressure (7.5GPa), extreme high vacuum (outer space), radiation (1000 times human lethal dose), extreme environments such as considerable doses), ultraviolet rays, and organic solvents.
Finding the problem
The genome analysis of the Tardigrade is currently in progress and has not been completely decoded. In other words, the correlation from the genotype to the phenotype has not been elucidated, and the gene expressing extreme environmental resistance has not been identified.
Argument
In general, when a living organism loses water from a cell, the cell and biological material are structurally broken and die. In other words, it means that the body tissue of the Tardigrade with dry resistance is protected from structural collapse due to drying by some mechanism.
Recent research has led to the identification of proteins (CAHS protein, SAHS protein, LEAM protein, MAHS protein) specific to the Tardigrade, and these proteins are now considered to be “the true nature of the mechanism”.
Conclusion
Therefore, I would like to contribute to the creation of a correlation map from the genotype to the phenotype based on the genome analysis data of the Tardigrade, and to identify the genes that express extreme environmental resistance.
Examining the conclusion
By studying with Associate Professor Kazuharu Arakawa, who is known by the achievement of establishing a whole genome analysis method using ultra-trace DNA derived from a single individual micro-organism, such as promoting the development of an ultra-trace analysis system and enabling whole genome analysis from about 50 pg of DNA that can be extracted from a single Tardigrade, I am sure that I could obtain various perspectives regarding my research and it would open up new horizons for me.
Therefore, I believe that Keio University’s Faculty of Environment and Information Studies is the most suitable place for pursuing my research and social contributions, and I am aspiring to enter your school and study in your laboratory.
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