Changes in patterns and synthesis of proteins in embryonic neural retina studied by 2-dimensional gel electrophoresis

Changes in protein patterns during early differentiation of embryonic neural retina (chick) were studied by 2-dimensional gel electrophoresis. The procedures employed here made it possible to visualize the overall population of proteins present in the tissue at a given time and, on the same gel to distinguish labeled from unlabeled proteins. 2-Dimensional gels were stained by a highly sensitive silver stain to visualize, map and quantitate proteins (and polypeptides) resolved by electrophoresis; the same gels were then autoradiographed in order to differentiate between actively synthesized and pre-existing proteins at each development stage. The effectiveness of this combinative analysis was first verified by identifying and localizing glutamine synthetase, an inducible enzyme marker of retina differentiation. Next, protein patterns in retina tissue at 2 embryonic ages were compared. Of the large number of spots visualized by the above methods approximately 10% showed distinct qualitative-quantitative developmental changes; these were grouped into 7 classes representative of major modes of alteration of protein patterns during cell differentiation.