Morphogenetic substances from sea urchin eggs. Isolation of animalizing and vegetalizing substances from unfertilized eggs of Paracentrotus lividus

Abstract

A method is described for the isolation of morphogenetic substances from mature, unfertilized eggs of the sea urchin Paracentrotus lividus. A complete separation of several different substances with specific animalizing or vegetalizing effect on the early development of sea urchins, when tested on whole eggs and on isolated animal and vegetal halves, was achieved by chromatography on Dowex 50 W-X2 and on Sephadex G-25. The results suggest that developmental processes can be influenced by various types of substances that may preexist in the unfertilized eggs. Two of the animalizing substances were obtained extensively purified. According to their ultraviolet absorption curves, on may contain tryptophan and the other consist of a nucleotide. They both exhibit a very high specific activity but differ significantly in their morphogenetic specificity. One induces strong animalization when tested on animal halves but has no effect when tested on whole eggs or on vegetal halves. In contrast, the other shows a strong animalizing activity in all three test systems. The high specific activity of the purified animalizing substances is demonstrated by their ability in very low concentrations to force the animal halves into their most extreme animal type of differentiation, i.e., with stereocilia all around the blastula wall, and to induce a differentiation on the vegetal halves not only to plutei but to a new extreme animalized larval type, the radial type. This type of vegetal half is characterized by the presence in the early stages of an apical tuft, and a further development with a thick ectoderm covering about half the body and with the skeleton in equatorial and radial position.