The distribution and renewal of RNA in retinal rods.

The distribution and renewal of RNA in mature rod visual cells has been studied by histochemical and autoradiographic technique in the rat and the frog. Staining with methyl green and pyronin, combined with ribonuclease extraction, revealed the presence of RNA in the nucleus and inner segments of rods in both species. Synthesis of RNA was studied by injecting cytidine-H, a radioactive precursor of RNA. Within 15 minutes after the injection, radioactive RNA could be detected in the nuclei of retinal rods in both the rat and the frog. RNA formation was not observed in other parts of the cell. By 1 hour after the injection, the new RNA began to move out of the nucleus and into the inner segment. This process was similar in both species, although it occurred more rapidly in the rat. These results demonstrate that RNA is continually renewed in mature visual cells and that inner segment RNA and nuclear RNA are both produced in the nucleus. The effect of prolonged bright light or total darkness on the renewal of RNA in retinal rods was studied in the frog. In both of these experimental situations RNA formation was depressed by a significant and similar amount.