ACTIONS OF COLCHICINE ON MORPHOGENESIS OF ACETABULARIA

The paper reports on interactions of colchicine with certain morphogenetic processes in nucleate and enucleated cells of the green algae Acetabularia. The strictly polarized stalk growth was found to be only slightly affected by the pseudoalkaloid. Cap formation, however, was strongly inhibited. The inhibition effect was reversible in nucleate cells, but irreversible in the enucleated cells. According to results of grafting experiments it is concluded that colchicine exerts no effect on the production and on the function of the morphogenetic substances which determine the special properties of the species. It appears that the inhibition is caused by the stable inactivation of rather unspecific substances, which are necessary for the initiation of certain morphogenetic events during cell ontogeny. The production of these substances by the nucleus, however, is not affected by colchicine. Experimental evidence was received that they are released from the nucleus into the cytoplasm in a precursor stage, which is not affected by the pseudo-alkaloid. It is proposed that these substances represent protein which is able to become functionally active in morphogenesis by specific structural changes. Similar conclusions were drawn from results of experiments on the influence of colchicine on the differentiation of cysts from cap ray plasm. The behaviour of the substances which are influenced by colchicine and which are involved in the formation of a new polarity axis of a cell, shows similarities to that of the nonspecies specific morphogenetic substances". © 1969 Springer-Verlag."