Rate of Movement and Composition of Rapidly Transported Proteins in Regenerating Olfactory Nerve

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Abstract
In a previous study, 3 successive groups of regenerative fibers, growing initially at 5.8, 2.1 and 0.8 mm/day, were observed in the regenerating garfish olfactory nerve. In the present study, fast axonal transport in the most rapidly regenerating axons (phase I and II) was examined. Rapid transport in phase I fibers occurred at a velocity of 208 .+-. 9 mm/day at 23.degree. C, a rate identical to that measured in intact nerves. This 1st phase of regenerating fibers represents only 3-5% of the original axonal population but each fiber appears to contain 6-16 times more transported radioactivity than an axon in an intact nerve. Subcellular distribution of rapidly moving material in phase I and II fibers was closely related to the distribution obtained in intact nerves. Small but significant differences indicate a shift of the transported radioactivity from a heavier to a lighter axonal membranous fraction. This shift might be characteristic of the immature membrane of a growing axon. The polypeptide distribution of transported radioactivity was similar to that of a normal nerve, with most of the radioactivity associated with high-MW polypeptides.