Protein maintenance and degradation are examined in the
severed distal (anucleate) portions of crayfish medial giant
axons (MGAs), which remain viable for over 7 months following
axotomy. On polyacrylamide gels, the silver-stained
protein banding pattern of anucleate MGAs severed from
their cell bodies for up to 4 months remains remarkably similar
to that of intact MGAs. At 7 months postseverance, some
(but not all) proteins are decreased in anucleate MGAs compared
to intact MGAs. To determine the half-life of axonally
transported proteins, we radiolabeled MGA cell bodies and
monitored the degradation of newly synthesized transported
proteins. Assuming exponential decay, proteins in the fast
component of axonal transport have an average half-life of
14 d in anucleate MGAs and proteins in the slow component
have an average half-life of 17 d. Such half-lives are very
unlikely to account for the ability of anucleate MGAs to survive
for over 7 months after axotomy.This work was supported by an ATP grant to G.D.B.Neuroscienc
