Evidence that regenerating optic axons maintain long-term growth in the lizard Ctenophorus ornatus: growth-associated protein-43 and gefiltin expression.
In the lizard, Ctenophorus ornatus, the optic nerve regenerates but animals remain blind via the experimental eye, presumably as a result of axons failing to consolidate a retinotopic map in the optic tectum. Here we have examined immunohistochemically the expression of the growth-associated protein GAP-43 and the low-molecular-weight intermediate filament protein gefiltin, up to one year after optic nerve crush. Both proteins were found to be permanently up-regulated, suggesting that regenerating axons are held in a permanent state of re-growth. We speculate that, in the lizard, the continued expression of GAP-43 and the failure to switch from the expression of low- to high-molecular-weight intermediate filament proteins are associated with the inability to consolidate a retinotopic projection.
Rodger
J
J
Department of Zoology, The University of Western Australia, WA 6907, Nedlands, Australia. jrodger@cyllene.uwa.edu.au
Bartlett
C A
CA
Harman
A M
AM
Thomas
C
C
Beazley
L D
LD
Dunlop
S A
SA
D000818:Animals; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D029941:Fish Proteins; D019922:GAP-43 Protein / Q000032:analysis / Q000235:genetics*; D005786:Gene Expression Regulation / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007381:Intermediate Filament Proteins / Q000032:analysis / Q000235:genetics*; D008116:Lizards; D009409:Nerve Crush; D009412:Nerve Fibers / Q000502:physiology; D009416:Nerve Regeneration / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D009900:Optic Nerve / Q000166:cytology / Q000502:physiology*; D013477:Superior Colliculi / Q000502:physiology; D013997:Time Factors
D029941:Fish Proteins; D019922:GAP-43 Protein; D007381:Intermediate Filament Proteins; C085833:gefiltin protein, Carassius auratus