Neurotrophic dependence of macromolecular synthesis in the early limb regenerate of the newt, Triturus.

The well-documented nerve dependence of limb regeneration in the newt was analysed by study of accumulation of newly synthesized macromolecules following denervation. The specific activity of RNA and DNA in the denervated early regenerate bud was determined following intraperitoneal injection of [H]-uridine and [H]-thymidine. Results showed an outburst in the incorporation into RNA and DNA which reached a peak 3 h after denervation for the former and 7 h for the latter. There was then a decline in incorporation to a plateau about 50-60% of the control non-denervated side within 48 h. Combining these results with our previous demonstration of a similar outburst in the accumulation of newly synthesized protein with a peak at 4 h, the sequence of the outbursts was in order RNA, protein and DNA. The results are interpreted to mean that the nerve influences either macromolecular synthesis or macromolecular processing and turnover, and therefore accumulation in the regenerate.