The neurotrophic influence on RNA precursor incorporation into polyribosomes of regenerating adult newt forelimbs

This study was designed to determine the effect of denervation on RNA and protein precursor incorporation into polyribosomes of nerve‐independent regenerates of the adult newt, Notophthalmus viridescens. The three stages of regeneration chosen for experimentation were the late paddle‐early digit stage (day 21), the 2–3 digit stage (day 28) and the 3–4 digit stage (day 35). Right forelimbs were denervated two days prior to polyribosome extraction while left forelimbs served as controls. To measure precursor incorporation, each newt was given either (1) H 3 ‐uridine (six hours), (2) Na 3 P 32 O 4 (90 minutes), or (3) H 3 ‐amino acids (60 minutes). Following incorporation, regenerates were prepared for examination of either polysome profiles or polysomal RNA profiles. A technique was used which yielded undegraded, non‐membrane bound polyribosomes relatively uncontaminated by labeled cosedimenting material. It was found that denervation reduced the incorporation of RNA precursors into both ribosomal and putative messenger RNA of polyribosomes of all three stages examined. Of the three stages tested, the 35 day stage was least affected by denervation. Amino acid incorporation into polysomal nascent peptides of regenerates was also adversely affected.