PATTERN OF RNA SYNTHESIS IN THE SCIATIC NERVE OF THE HEN DURING WALLERIAN DEGENERATION

The pattern of synthesis of rapidly‐labelled RNA of hen sciatic nerve was studied during Wallerian degeneration. At 2,4,8, 16 and 30 days of degeneration the proximal and distal stumps of the severed nerve as well as the intact contralateral sciatic nerve (functional control) were excised and incubated with either [5‐ 3 H]uridine or [2‐ 14 C]uridine for 0.5 h. The electrophoretic pattern of RNA from the normal adult sciatic nerve showed that most of the radioactivity was incorporated into RNA species migrating between the 18 S and 4 S components of the bulk RNA. The synthesis of RNA was sensitive to actinomycin‐D, an indication that it was directed by a DNA template. The electrophoretic patterns of the rapidly‐labelled RNA in the proximal and distal nerve stumps demonstrated a change following nerve section. After 2–4 days of Wallerian degeneration the degenerating distal nerves incorporated more radioactivity in the 4 S region than the corresponding controls, but at 8 and 16‐days after degeneration relatively more label appeared in higher molecular weight RNA species. In the intact sciatic nerve of the operated hens progressively more radioactivity was detected in the 4 S region with increasing time after the contralateral nerve section. At each stage of Wallerian degeneration the specific radioactivities of RNA in the control nerves from experimental hens were higher than those of the normal adult sciatic nerve. These results indicated a change of RNA metabolism in increased functional activity and during Wallerian degeneration.