[Effect of heterogeneous inducers on the ectoderm of the early gastrula in Rana temporaria in vitro. IV. The inductive effect of embryonic tissue extracts after ribonuclease and proteinase treatment].

An attempt was undertaken to determine the chemical nature of the neuralizing and lens-inducing effect of the retina and brain extracts from 7-8 day old chick embryos. These extracts were treated with immobilized enzymes (RNAse, proteinase K) and the effect of treatment was then estimated in the organ cultures (reacting tissue - early gastrula ectoderm). The effect of the enzymes was studied in different experimental variants which allowed to exclude the effect of the own proteases and temperature on the inducing activity of the extracts under study. The neuralizing activity of the retinal extract was shown to preserve after its treatment with RNAse but to be almost fully lost (or decrease) after proteolytic hydrolysis. Proteinase suppressed as well completely the lens-inducing effect of the extract from the chick embryo brain. A conclusion is drawn that the inducing activity of the extracts under study is due to proteins, rather than to RNA.