Inducing activity of fractionated microsomal material from theXenopus laevis gastrula stage.

The postmitochondrial supernatant fromXenopus gastrulae has been fractionated on sucrose gradients. Part of the microsomal material was treated with EDTA, which dissociates most of the polysomal and monosomal material into ribosomal subunits. In addition, a series of pooled fractions from the EDTA treated gradients has been applied to discontinuous gradients in more concentrated sucrose to separate membranous material from the remaining microsomal components.Pooled fractions from all gradients have been tested for inductive activity on amphibian gastrula ectoderm. The spinocaudal (trunk and tail) inducing activity was to some extent eneriched in the membrane fractions.