title: Positive injury signals induce growth and prolong survival in Aplysia neurons.
abstract: Injury to a peripheral nerve initiates changes that can lead to regeneration of the damaged axons. How information about a distant injury is communicated to the cell body is not clear. Using the nervous system of Aplysia californica, we tested the idea that some of this information is conveyed via positive injury signals-axoplasmic proteins that are activated at the injury site and transported to the cell soma. We collected these proteins by crushing pedal nerves and then placing a ligation proximal to the ligation. The contralateral nerves were ligated as controls. Twenty h later, axoplasm was extruded from the nerve segment just distal to the ligation on the crushed nerves (cr/lig) and on the control nerves (lig). The total proteins were rhodaminated and injected into the cytoplasm of neurons in vitro to look for nuclear import. Punctate fluorescence was detected in the nucleus of all seven neurons injected with the cr/lig axoplasm. Only two of five neurons injected with lig axoplasm had any fluorescence. Equal amounts of cr/lig and lig axoplasm were then injected directly into the cell bodies of neurons maintained in vitro. The cells injected with cr/lig axoplasm exhibited renewed growth and significantly longer survival: 25.9 +/- 2.1 days (mean +/- SEM: n = 22) relative to the cells injected with lig axoplasm (15.3 +/- 1.2 days; n = 14) and to those that were not injected (12.2 +/- 1.7 days; n = 24). Fractionation of the cr/lig axoplasm indicated that different factors are responsible for growth and survival.
authors.affiliation: Department of Anatomy and Cell Biology, 1204 Black Building, Columbia University, W. 168th Street, New York, New York 10032, USA.
authors.forename: X P
authors.initials: XP
authors.lastname: Zhang
authors.forename: R T
authors.initials: RT
authors.lastname: Ambron
mesh_terms: D000818:Animals; D001048:Aplysia / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D001370:Axonal Transport / Q000502:physiology*; D019771:Axotomy / Q000009:adverse effects; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D009409:Nerve Crush / Q000009:adverse effects; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D009419:Nerve Tissue Proteins