The Journal of Cell Biology, Vol 98, 2118-2125, Copyright © 1984 by The Rockefeller University Press

ARTICLES

The cytoskeletal system of nucleated erythrocytes. III. Marginal band function in mature cells

J Joseph-Silverstein and WD Cohen

Marginal bands (MBs) of microtubules are believed to function during morphogenesis of nonmammalian vertebrate erythrocytes, but there has been little evidence favoring a continuing role in mature cells. To test MB function, we prepared dogfish erythrocytes with and without MBs at the same temperature by (a) stabilization of the normally cold- labile MB at 0 degree C by taxol, and (b) inhibition of MB reassembly at room temperature by nocodazole or colchicine. We then compared the responses of these cells to mechanical stress by fluxing them through capillary tubes. Before fluxing , cells with or without MBs had normal flattened elliptical shape. After fluxing , deformation was consistently observed in a much greater percentage of cells lacking MBs. The difference in percent deformation between the two cell types was highly significant. That the MB is an effector of cell shape was further documented in studies of the formation of singly or doubly pointed dogfish erythrocytes that appear during long-term incubation of normal cells at room temperature. On-slide perfusion experiments revealed that the pointed cells contain MBs of corresponding pointed morphology. Incubation of cells with and without MBs showed that they become pointed only when they contain MBs, indicating that the MB acts as a flexible frame which can deform and support the cell surface from within. To test this idea further, cells with and without MBs were exposed to hyperosmotic conditions. Many of the cells without MBs collapsed and shriveled , whereas those with MBs did not. The results support the view that the MB has a continuing function in mature erythrocytes, resisting deformation and/or rapidly returning deformed cells to an efficient equilibrium shape in the circulation.
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This article has been cited by other articles:

• Conrad, M., DeNobile, J., Chaikhoutdinov, I., Escribano, D., Lee, K.-G., Cohen, W. D. (2004). Cytoskeletal Organization of Limulus Amebocytes Pre- and Post-Activation: Comparative Aspects. Biol. Bull. 207: 56-66 [Abstract] [Full Text]  
• Zhu, J, Bloom, S., Lazarides, E, Woods, C (1995). Identification of a novel Ca(2+)-regulated protein that is associated with the marginal band and centrosomes of chicken erythrocytes. J. Cell Sci. 108: 685-698 [Abstract]  

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