POSITIONAL INFORMATION AND WHORL MORPHOGENESIS IN POLYSPHONDYLIUM

Cellular slime molds of the genus Polysphondylium periodically release cell masses from the base of culminating fruiting bodies. These masse s quickly undergo a change in symmetry from spherical to radial as the y differentiate into distinctive arrays of secondary fruiting bodies a rranged about a primary axis of stalk cells. Here we show that a major event in whorl morphogenesis is the activation of a prestalk-specific promoter early and globally in newly forming whorls. With time, trans cript synthesis and amplification become restricted to the equator of the whorl and then to patches which define where secondary tip morphog enesis will occur. The localization of early prestalk message synthesi s depends on positional information, in contrast to the establishment of early prestalk/prespore patterns in both Polysphondylium and Dictyo stelium. (C) 1996 Academic Press, Inc.