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Author Notes:

Correspondence: Shoichiro Ono; Email: sono@emory.edu

Acknowledgments: The wild-type C. elegans strain was provided by the Caenorhabditis Genetics Center, which is supported by the National Institute of Health National Center for Research Resources.


Research Funding:

This work was supported by grants from the Ministry of Education, Science and Culture, Japan (Grant number 20570075) to T.O. and the National Institute of Health (R01 AR48615) and University Research Committee of Emory University to S.O.


  • troponin
  • actin
  • actin-linked regulation
  • non-striated muscle
  • tardigrades

Detection of a troponin I-like protein in non-striated muscle of the tardigrades (water bears)


Journal Title:



Volume 1, Number 2


, Pages 96-102

Type of Work:

Article | Final Publisher PDF


Tardigrades, also known as water bears, have somatic muscle fibers that are responsible for movement of their body and legs. These muscle fibers contain thin and thick filaments in a non-striated pattern. However, the regulatory mechanism of muscle contraction in tardigrades is unknown. In the absence of extensive molecular and genomic information, we detected a protein of 31 kDa in whole lysates of tardigrades that cross-reacted with the antibody raised against nematode troponin I (TnI). TnI is a component of the troponin complex that regulates actin-myosin interaction in a Ca2+-dependent and actin-linked manner. This TnI-like protein was co-extracted with actin in a buffer containing ATP and EGTA, which is known to induce relaxation of a troponin-regulated contractile system. The TnI-like protein was specifically expressed in the somatic muscle fibers in adult animals and partially co-localized with actin filaments in a non-striated manner. Interestingly, the pharyngeal muscle did not express this protein. These observations suggest that the non-striated somatic muscle of tardigrades has an actin-linked and troponin-regulated system for muscle contraction.

Copyright information:

© 2011 Landes Bioscience

This is an Open Access work distributed under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported License (http://creativecommons.org/licenses/by-nc/3.0/).

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