4S RNA is present in regenerating optic axons of goldfish.

Regenerating optic axons of goldfish were loaded with [3H]RNA by injecting [3H]uridine into the eye and allowing time for the radioactivity to be delivered to the optic tectum. The axons were subsequently removed from the tecta by cutting the optic nerve and allowing the optic axons in the tectum to degenerate. Analysis of tectal [3H]RNA by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a selective loss of tritiated 4S RNA and not ribosomal RNA from the denervated tecta. These results support the hypothesis that regenerating optic axons of goldfish grow back into the tectum carrying 4C but not ribosomal RNA.