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Title: Mechanics dictate where and how freshwater planarians fission

Abstract

Asexual freshwater planarians reproduce by tearing themselves into two pieces by a process called binary fission. The resulting head and tail pieces regenerate within about a week, forming two new worms. Understanding this process of ripping oneself into two parts poses a challenging biomechanical problem. Because planarians stop “doing it” at the slightest disturbance, this remained a centuries-old puzzle. In this paper, we focus on Dugesia japonica fission and show that it proceeds in three stages: a local constriction (“waist formation”), pulsation—which increases waist longitudinal stresses—and transverse rupture. We developed a linear mechanical model with a planarian represented by a thin shell. The model fully captures the pulsation dynamics leading to rupture and reproduces empirical time scales and stresses. It asserts that fission execution is a mechanical process. Moreover, we show that the location of waist formation, and thus fission, is determined by physical constraints. Together, our results demonstrate that where and how a planarian rips itself apart during asexual reproduction can be fully explained through biomechanics.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Univ. of California, San Diego, CA (United States)
Publication Date:
Research Org.:
Univ. of California, San Diego, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1529223
Grant/Contract Number:  
FG02-04ER54738
Resource Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 41; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; planarians; biomechanics; fission; rupture; traction forces

Citation Formats

Malinowski, Paul T., Cochet-Escartin, Olivier, Kaj, Kelson J., Ronan, Edward, Groisman, Alexander, Diamond, Patrick H., and Collins, Eva-Maria S. Mechanics dictate where and how freshwater planarians fission. United States: N. p., 2017. Web. doi:10.1073/pnas.1700762114.
Malinowski, Paul T., Cochet-Escartin, Olivier, Kaj, Kelson J., Ronan, Edward, Groisman, Alexander, Diamond, Patrick H., & Collins, Eva-Maria S. Mechanics dictate where and how freshwater planarians fission. United States. doi:10.1073/pnas.1700762114.
Malinowski, Paul T., Cochet-Escartin, Olivier, Kaj, Kelson J., Ronan, Edward, Groisman, Alexander, Diamond, Patrick H., and Collins, Eva-Maria S. Mon . "Mechanics dictate where and how freshwater planarians fission". United States. doi:10.1073/pnas.1700762114. https://www.osti.gov/servlets/purl/1529223.
@article{osti_1529223,
title = {Mechanics dictate where and how freshwater planarians fission},
author = {Malinowski, Paul T. and Cochet-Escartin, Olivier and Kaj, Kelson J. and Ronan, Edward and Groisman, Alexander and Diamond, Patrick H. and Collins, Eva-Maria S.},
abstractNote = {Asexual freshwater planarians reproduce by tearing themselves into two pieces by a process called binary fission. The resulting head and tail pieces regenerate within about a week, forming two new worms. Understanding this process of ripping oneself into two parts poses a challenging biomechanical problem. Because planarians stop “doing it” at the slightest disturbance, this remained a centuries-old puzzle. In this paper, we focus on Dugesia japonica fission and show that it proceeds in three stages: a local constriction (“waist formation”), pulsation—which increases waist longitudinal stresses—and transverse rupture. We developed a linear mechanical model with a planarian represented by a thin shell. The model fully captures the pulsation dynamics leading to rupture and reproduces empirical time scales and stresses. It asserts that fission execution is a mechanical process. Moreover, we show that the location of waist formation, and thus fission, is determined by physical constraints. Together, our results demonstrate that where and how a planarian rips itself apart during asexual reproduction can be fully explained through biomechanics.},
doi = {10.1073/pnas.1700762114},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 41,
volume = 114,
place = {United States},
year = {2017},
month = {9}
}

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Works referenced in this record:

Strain, stress and stretch of peripheral nerve Rabbit experiments in vitro and in vivo
journal, January 1992

  • Kwan, Michael K.; Wall, Eric J.; Massie, Jenni
  • Acta Orthopaedica Scandinavica, Vol. 63, Issue 3, p. 267-272
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