Enhanced labeling of a retinal protein during regeneration of optic nerve in goldfish

Goldfish retinas were examined for changes in the labeling pattern of protein during regeneration of retinal ganglion cell axons following unilateral optic nerve crush. At various times after optic nerve crush the normal retinas were incubated in vitro with [3H] methionine and retinas from the opposite side of the treated fish were inculbated with [35S] methionine. The incubated retinas were combined and a soluble protein fraction was isolated and separated by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis. A band on the gel showing an elevated 35S to 3H ratio appeared at 5 days following optic nerve crush, increased to a maximum at 15 days, and was barely detectable at 45 days, during which time vision is known to return. On the basis of several criteria, the protein fraction showing the increased incorporation of methionine in retina after optic nerve crush appears to be of the tubulin class.