RNA Synthesis in the Rod Cell of the Rat

¹ Department of Physiology, Neurosensory Laboratory, School of Medicine, State University of New York at Buffalo, Buffalo, N. Y. 14214

Labeled RNA precursor was injected intravitreally into the rat. At subsequent time intervals, RNA was selectively extracted from rod cell inner segments and nuclei and fractionated by linear sucrose density ultracentrifugation. The nuclear sedimentation profile was complex at all times, and radioactivity levels were sustained above those of the inner segment up through 20 days after intraocular injection. The 4S was the first component labeled in the inner segment between two and three hours following injection. Indication of labeled RNA sedimenting in the region of 8-11S of the gradient was present in the inner segment at six and seven hours. The earliest signs of ribosomal RNA labeling were present at 18 hours and reached a maximum between 21 and 24 hours. The findings indicated that most RNA classes turnover at a low rate in the visual cell.

Note:
Recipient of a Research Career Program Award No. NB 14,254 from the National Institute of Neurological Diseases and Stroke, United States Public Health Service, Bethesda, Md.

Key Words: rod cell • visual cell • RNA metabolism • uridine uptake • visual cell fractionation

Submitted on June 11, 1971
Accepted on July 29, 1971