Regional protein patterns of the embryonic chick brain: developmental shifts and the effects of light stimulation.

The developmental changes in the regional protein patterns of the embryonic brain of chick were analysed by micro-two-dimensional polyacrylamide gel electrophoresis stained by a highly sensitive procedure with Coomassie Brilliant Blue G-250 that completely avoids background staining. More than 400 protein spots were resolved in a computerized plot. Many proteins of the various embryonic brain regions varied with age. At least six of these proteins changed remarkably during development. One of them (Mr 14K) was prominent at 6 days and disappeared after 12 days of incubation. One acidic protein (Mr 30K) appeared at 12 days together with two acidic protein spots near tubulin and increased with development. A group of more basic proteins (Mr 94K) was prominent at 6 day incubation and decreased during development. One more basic protein (Mr 20K) was first observed at 18 days of incubation in the metencephalon. It was identified as myelin basic protein, and strikingly increased in all brain regions until hatching. A group of basic proteins with high molecular weight (Mr 94K) appeared at day 12 of incubation, and increased remarkably before hatching. They were identified to be collagen associated with brain capillary vessels. Stimulation by intermittent light in ovo from day 10 to day 16 caused a retarded appearance of these collagen proteins, and an increased formation of tubulin in the optic lobe of the developing chick embryo.