Results of our work to date can be summarized as follows: 1) Small amounts of RNA appear to be axonally transported in normal goldfish optic nerves. 2) During regeneration of this nerve, the amount of RNA transported is greatly increased (approximately 10 times controls). EM autoradiographic results show that the RNA is primarily in elongating axons and growth cones. 3) Polyacrylamide gel electrophoresis of RNA in optic tecta receiving regenerating fibers indicates that the most enriched RNA fraction is small molecular weight 4S RNA (probably containing transfer RNA). We have postulated that transfer RNA is the only RNA species present in axons. 4) Putrescine a diamine associated in general with growing or developing tissue, is transported during nerve regeneration but not in normal fibers. In the coming year we plan the following experiments: 1) A study of axonal RNA transport in normal and regenerating rat sciatic nerves. We plan to crush the right nerve and then make bilateral injections of H3-uridine into the vicinity of the ventral horn cells giving rise to the sciatic nerve. RNA associated radioactivity is then assayed along the extent of both sciatic nerves. Characterization of the RNA by polyacrylamide gel electrophoresis and localization by EM autoradiography is also planned. 2) Using gel electrophoresis, we will analyze RNA in goldfish retinas and optic tecta following the intraocular injection of the RNA synthesis inhibitor cordycepin and H3-uridine, used as an RNA marker. These experiments attempt to characterize the molecular species of RNA which is axonally transported. Experiments are then repeated in regenerating nerves. 3) Experiments involving putrescine transport will be extended to the polyamine derivatives of putrescine, spermidine and spermine. We shall attempt to demonstrate the axonal transport (or lack of transport of the polyamines in normal and regenerating goldfish optic fibers. These experiments are being performed in an attempt to uncover the role of RNA in axonal regeneration and, in more general terms, to study the axonal movement of molecules during nerve growth. BIBLIOGRAPHIC REFERENCES: Gambetti, P., Ingoglia, N.A., Weis, P., and Autilio-Gambetti, L. RNA Distribution in Goldfish optic tectum after intraocular injection of H3-uridine. November, 1975 (Text Truncated - Exceeds Capacity)
NIH ExPorter
NIH ExPorter