Pattern formation in the cellular slime molds.

Abstract

The prestalk/prespore pattern within a slug of the cellular slime molds presents a simple model system to the studies of biological pattern formation. Formation of a slug is accompanied by differentiation of prestalk and prespore cells which occupy the front part and the rear part of a slug, respectively. The proportion of the prestalk to prespore cells is regulated to be constant irrespective of the slug size. Isolated prespore and prestalk portion can regenerate the normal pattern by cell type conversion.Many experiments indicate that sorting out of the cells play an important role in both formation and regulation of the pattern. Differences between prestalk and prespore cells in chemotaxis toward cAMP are likely to be involved in the sorting out.Cells similar to prestalk cells in many respect are scattered in the prespore region. They are different from prestalk cells in behaviour and called anterior-like cells. Our observations indicate that they are constantly exchanging with prestalk cells during migration of the slug.Several experimental systems have been deviced in which cells can differentiate without morphogenesis. It has also been found that the normal spatial pattern of prestalk and prespore cells is not necessarily required of the proportion regulation between them.