Eur. Phys. J. E 1, 215-225
Elastic properties of nematoid arrangements formed by amoeboid cells
R. Kemkemer1 - D. Kling1 - D. Kaufmann2 - H. Gruler1
1 Department of Biophysics, University of Ulm, 89069 Ulm, Germany
2 Department of Human Genetics,
University of Ulm, 89069 Ulm, Germany
hans.gruler@physik.uni-ulm.de
Received 3 May 1999 and Received in final form 29 September 1999
Abstract
In culture migrating and interacting amoeboid cells can form nematoid
arrangements in analogy to a nematic liquid crystal phase. A nematoid
arrangement is formed if the interaction has an apolar symmetry. Different cell
types like human melanocytes (= pigment cells of the skin), human fibroblasts
(= connective tissue cells), human osteoblasts (= bone cells), human adipocytes
(= fat cells) etc., form a nematoid structure. Our hypothesis is that elastic
properties of these nematoid structures can be described in analogy to that of
classical nematic liquid crystals. The orientational elastic energy is derived
and the orientational defects (disclination) of nematoid arrangements are
investigated. The existence of half-numbered disclinations shows that the
nematoid structure has an apolar symmetry. The density- and order parameter
dependence of the orientational elastic constants and their absolute values are
estimated. From the defect structure, one finds that the splay elastic constant
is smaller than the bend elastic constant (melanocytes). The core of a
disclination is either a cell free space or occupied by non oriented cells
(isotropic state), by a cell with a different symmetry, or by another cell type.
PACS
87.10.+e General theory and mathematical aspects
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61.30.-v Liquid crystals
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61.30.Jf Defects in liquid crystals
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
