Nematic order-disorder state transition in a liquid crystal analogue formed by oriented and migrating amoeboid cells |
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Authors: | R Kemkemer V Teichgräber S Schrank-Kaufmann D Kaufmann H Gruler |
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Institution: | (1) Department of bioPhysics, University of Ulm, D-89069 Ulm, Germany, DE;(2) Department of Human Genetics, University of Ulm, D-89069 Ulm, Germany, DE |
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Abstract: | In cell culture, liquid crystal analogues are formed by elongated, migrating, and interacting amoeboid cells. An apolar nematic
liquid crystal analogue is formed by 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. The nematic analogue is quite
well described by i) a stochastic machine equation responsible for cell orientation and ii) a self-organized extracellular
guiding signal, E2, which is proportional to the orientational order parameter as well as to the cell density. The investigations were mainly
made with melanocytes. The transition to an isotropic state analogue can be accomplished either by changing the strength of
interaction (e.g. variation of the cell density) or by influencing the cellular machinery by an externally applied signal: i) An isotropic
gaseous state analogue is observed at low cell density (melanocytes/mm^2) and a nematic liquid crystal state analogue at higher cell density. ii) The nematic state analogue disappears
if the bipolar shaped melanocytes are forced to become a star-like shape (induced by colchicine or staurosporine). The analogy
between nematic liquid crystal state analogue formed by elongated, migrating and interacting cells and the nematic liquid
crystal phase formed by interacting elongated molecules is discussed.
Received 2 August 1999 and Received in final form 5 January 2000 |
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Keywords: | PACS 87 18 -h Multicellular phenomena – 87 18 Ed Aggregation and other collective behavior of motile cells – 64 70 -p Specific phase transitions |
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