Kumamushi Genome Project

Genome sequence of an extreme animal

Kumamushi is the tardigrades (water bears) in Japanese. This organism is scientifically interesting from a phylogenetic view point that water bears are believed to sit between worms and arthropods on the tree of life. Besides, this tiny animal is famous as they can survive the following extreme environments when dehydrated.

  • High (151°C)[1] and low (-273°C)[2] temperatures.
  • High (7.5GPa)[3] and low (open space vacuum)[4] pressures.
  • X-rays (5,000Gy)[5], Gamma-rays (6,000Gy)[6,7], and Helium ion beam (7,000Gy)[7] radiations.

Our goal is to reveal the molecular basis of tolerance to those enormous stresses by decoding the genome sequence of this creature.


We developed the efficient rearing system[8] of the extremotolerant tardigrade Ramazzottius varieornatus, one of the desiccation tolerant water bears. We isolated a strain named "YOKOZUNA-1" from an egg and established a culture for our genome project.


  1. Rahm P.G. (1921) Biologische und physiologische Beiträge zur Kenntnis de Moosfauna. Z. allgem. Physiol. 20, 1-35.
  2. Becquerel P. (1950) La suspension de la vie au dessous de 1/20 K absolu par demagnetization adiabatique de l’alun de fer dans le vide les plus eléve. C. R. hebd. Séances Acad. Sci. Paris 231, 261–263.
  3. Ono F. et al. (2008) Effect of high hydrostatic pressure on to life of the tiny animal tardigrade. J. Phys. Chem, Solids 69, 2297-2300.
  4. Jönsson K.I. et al. (2008) Tardigrades survive exposure to space in low Earth orbit. Curr. Biol. R729-R731.
  5. May R.M. et al. (1964) Action différentielle des rayons x et ultraviolets sur le tardigrade Macrobiotus areolatus, a l’état actif et desséché, Bull. Biol. Fr. Belg. 98, 349–367.
  6. Jönsson K.I. et al. (2005) Radiation tolerance in the eutardigrade Richtersius coronifer. Int. J. Radiat. Biol. 81, 649–656.
  7. Horikawa D.D. et al. (2006) Radiation tolerance in the tardigrade Milnesium tardigradum. Int. J. Radiat. Biol. 82, 843–848.
  8. Horikawa D.D. et al. (2008) Establishment of a rearing system of the extremotolerant tardigrade Ramazzottius varieornatus: a new model animal for astrobiology. Astrobiology, 8, 549-556.