Organic compounds including carbohydrates, amino acids, and lipids have a large diversity (and a much/less variation) in the stable isotopic composition for H, C, N, O, S, which is cased by isotopic discrimination due to the isotope effect and branched flux on ‘key’ biochemical processes in biosynthetic (or anabolic) and metabolic (or catabolic) pathways in organisms. An identification or assignment of ‘key process’ in these pathways is indispensable for better understanding of the isotopic composition and/or discrimination found in organisms, as well as of the accuracy and precision on the isotope evidence in application studies.
We would love to contribute to the understanding in-depth the complex biogeochemical processes in our planet, by using the following studies:

    • Illumination of ‘key process’ responsible for controlling molecular and stable isotopic compositions of organic compounds in organisms’ physiology;
    • Assessment of ‘universality vs. predictable fluctuation’ or ‘homogeneity vs. heterogeneity’ in the change of the compositions with respect to the ‘key process’ in nature; and
    • Illustration of ‘functional & energetic ecology’ in biogeochemical cycles.

To do that, we love/enjoy the challenges for developing new analytical methods of (or new methodologies using) compound-specific or position-specific isotope analysis of organic compounds in natural samples.


Yoshito Chikaraishi
Michie Tomoda 
Ph.D. Student
Yuko Takizawa

Research Interests

Fundamental knowledge on stable isotopes

High resolution food web viewed via 15N/14N of amino acids

Advances in compound-specific stable isotope analysis of amino acids

Contact Address

Name :   Yoshito Chikaraishi
Adress:  Isotope Physiology, Ecology, & Geochemistry Group,
              Institute of Low Temperature Science, Hokkaido University,
              Kita-19, Nishi-8, Kita-ku, Sapporo 060-0819, Japan
TEL:      +81-11-706-5472
E-mail:   ychikaraishi_AT_lowtem.hokudai.ac.jp