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Oorschot DE, Jones DG. Effect of cytosine arabinoside on rat cerebral explants: fibroblasts and reactive microglial cells as the primary cellular barrier to neurite growth. Neurosci Lett 1989; 102:332-6. [PMID: 2812510 DOI: 10.1016/0304-3940(89)90101-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Rat cerebral explants were cultured in the presence or absence of the mitotic inhibitor cytosine arabinoside (AraC) to investigate whether reports of increased neurite outgrowth may be primarily related to a decreased incidence of fibroblastic-reactive microglial cells. Treated explants were exposed to AraC from 7 to 10 days in vitro (DIV) and processed for transmission electron microscopy at 18 DIV. Morphometric analysis of the outgrowth zone revealed a statistically significant decrease in the incidence of fibroblastic-reactive microglial cells (from 12 to 0%), and a significant increase in the incidence of protoplasmic astrocytic-epithelial cells (from 82 to 96%), for AraC-treated explants compared to controls. In contrast, the incidence of fibrous astrocytes was similar to that of control explants (4 and 6%, respectively). Thus, it appears that AraC may primarily enhance neurite growth by curtailing the proliferation of fibroblastic-reactive microglial cells. These results suggest that fibroblastic-reactive microglial cells, rather than fibrous astrocytes, may constitute the primary cellular barrier to neurite growth.
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Affiliation(s)
- D E Oorschot
- Department of Anatomy, University of Otago, Dunedin, New Zealand
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Harel A, Fainaru M, Shafer Z, Hernandez M, Cohen A, Schwartz M. Optic nerve regeneration in adult fish and apolipoprotein A-I. J Neurochem 1989; 52:1218-28. [PMID: 2494299 DOI: 10.1111/j.1471-4159.1989.tb01869.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Fish optic nerves, unlike mammalian optic nerves, are endowed with a high capacity to regenerate. Injury to fish optic nerves causes pronounced changes in the composition of pulse-labeled substances derived from the surrounding non-neuronal cells. The most prominent of these injury-induced changes is in a 28-kilodalton (kDa) polypeptide whose level increases after injury, as revealed by one-dimensional gel electrophoresis and autoradiography. The present study identified as apolipoprotein A-I (apo-A-I) a polypeptide of 28 kDa in media conditioned by regenerating fish optic nerves. The level of this polypeptide increased after injury by approximately 35%. Apo-A-I was isolated by gel-permeation chromatography from delipidated high-density lipoproteins (HDL) that had been obtained from carp plasma by sequential ultracentrifugation. Further identification of the purified protein as apo-A-I was based on its molecular mass (28 kDa) as determined by gel electrophoresis, amino acid composition, and microheterogeneity studies. The isolated protein was further analyzed by immunoblots of two-dimensional gels and was found to contain six isoforms. Western blot analysis using antibodies directed against the isolated plasma protein showed that the 28-kDa polypeptide in the preparation of soluble substances derived from the fish optic nerves (conditioned media, CM) cross-reacted immunologically with the isolated fish plasma apo-A-I. Immunoblots of two-dimensional gels revealed the presence of three apo-A-I isoforms in the CM of regenerating fish optic nerves (pIs: 6.49, 6.64, and 6.73). At least some of the apo-A-I found in the CM is derived from the nerve, as was shown by pulse labeling with [35S]methionine, followed by immunoprecipitation. The apo-A-I immunoactive polypeptides in the CM of the fish optic nerve were found in high molecular-weight, putative HDL-like particles. Immunocytochemical staining revealed that apo-A-I immunoreactive sites were present in the fish optic nerves. Higher labeling was found in injured nerves (between the site of injury and the brain) than in non-injured nerves. The accumulation of apo-A-I in nerves that are capable of regenerating may be similar to that of apo-E in sciatic nerves of mammals (a regenerative system); in contrast, although its synthesis is increased, apo-A-I does not accumulate in avian optic nerves nor does apo-E in rat optic nerves (two nonregenerative systems).
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Affiliation(s)
- A Harel
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
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Uchida Y, Tomonaga M. Neurotrophic action of Alzheimer's disease brain extract is due to the loss of inhibitory factors for survival and neurite formation of cerebral cortical neurons. Brain Res 1989; 481:190-3. [PMID: 2706462 DOI: 10.1016/0006-8993(89)90503-9] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cell cultures of neonatal rat cerebral cortex in a serum-free medium were used to investigate whether specific neurotrophic factors are accumulated or inhibitory factors for neuronal survival and neurite formation decrease in AD brain extract. Neurotrophic activity in brain extract was quantified by using the ELISA for microtubule-associated protein 2 (MAP2). Inhibitory factors, which blocked neurotrophic activity, were present in normal brain extract. In AD brain extract, loss of the inhibitory factors resulted in a relative increase in neurotrophic activity. The inhibitory factors in normal brain extract were retained on the ultrafiltration membrane with molecular weight cutoff of 10 kDa.
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Affiliation(s)
- Y Uchida
- Department of Clinical Pathology, Tokyo Metropolitan Institute of Gerontology, Japan
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Fainaru M, Schafer Z, Gavish D, Harel A, Schwartz M. Interactions between human and carp (Cyprimus carpio) low density lipoproteins (LDL) and LDL receptors. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1988; 91:331-8. [PMID: 3197401 DOI: 10.1016/0305-0491(88)90150-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1. We have compared the concentration and chemical composition of carp and human plasma lipoproteins and studied their interaction with human fibroblast LDL receptors. 2. The main lipoproteins in carp are of high density (HDL) in contrast to low density lipoproteins (LDL) in human. 3. Carp lipoproteins are devoid of apolipoprotein (apo) E, a major ligand for interaction with LDL receptors in mammals. 4. Carp very low density lipoproteins (VLDL) and LDL but not HDL nor apoA-I cross react with human LDL in their interaction with LDL receptors on human cultured fibroblasts. 5. Carp liver membranes possess high affinity receptors that are saturable and have calcium dependent ligand specificity (apoB and apoE) similar to human LDL receptor. Carp VLDL and LDL but not HDL nor its major apolipoprotein complexed to L-alpha-phosphatidylcholine dimyristoyl (apoA-I-DMPC) competed with the specific binding of human LDL to this receptor.
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Affiliation(s)
- M Fainaru
- Department of Medicine A, Kaplan Hospital, Rehovot, Israel
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Finklestein SP, Benowitz LI, Olson AJ, Perrone-Bizzozero NI, Majocha RE, Apostolides PJ. Conditioned media from the injured lower vertebrate CNS promote neurite outgrowth from mammalian brain neurons in vitro. Brain Res 1987; 413:267-74. [PMID: 3607477 DOI: 10.1016/0006-8993(87)91017-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Unlike most pathways of the mature mammalian central nervous system (CNS), the CNS of lower vertebrates can regenerate after jury, a capacity that may be due to the secretion of neurite-promoting factors from the injured CNS. We report that conditioned media (CM) from the injured optic nerve of the mature goldfish promoted marked neurite outgrowth from dissociated embryonic rat cortical and hindbrain neurons in serum-free, neuron-enriched culture. This property was not shared by CM from intact goldfish optic nerve, or from intact or injured optic nerve of mature rats. Neurite-promoting activity was obtained at concentrations as low as 100 ng total protein/ml of CM from injured goldfish optic nerve, and was associated with a distinctive morphology of neurite outgrowth. Due its properties of non-dialyzability, heat lability, and trypsin sensitivity, the neurite-promoting factor(s) appeared to be one or more protein species of MW greater than 12,000. Factors secreted by the regenerating CNS of lower vertebrates can directly promote outgrowth of mammalian CNS neurons.
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Bawnik Y, Harel A, Stein-Izsak C, Schwartz M. Environmental changes induced by growth-associated triggering factors in injured optic nerve of adult rabbit. Proc Natl Acad Sci U S A 1987; 84:2528-31. [PMID: 3470808 PMCID: PMC304687 DOI: 10.1073/pnas.84.8.2528] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Central nervous system (CNS) neurons of mammals regenerate poorly after axonal injury. However, if an injured CNS neuron (rabbit optic nerve) is supplied with appropriate soluble substances ("growth-associated triggering factors") derived from medium conditioned by regenerating fish optic nerve or newborn rabbit optic nerve, it can express regeneration-associated characteristics. Such characteristics include a general increase in protein synthesis, changes in synthesis of specific polypeptides, and sprouting of nerve fibers in culture. The present study of rabbit optic nerves demonstrates that such active substances affect the neuronal environment (i.e., the non-neuronal cells), thereby perhaps causing a shift in the environment from an inhibitory to a regenerative supportive one. Apparently, such an environment is spontaneously achieved in injured CNS nerves of lower vertebrates (e.g., fish optic nerves), which are regenerable. Treatment of injured rabbit optic nerve with soluble factors from medium conditioned by regenerating carp optic nerve resulted in a selective increase in proliferation ([3H]thymidine incorporation) of perineural cells and the appearance of a 12-kDa polypeptide in a homogenate derived from the nerve and its associated cells. This polypeptide may be related to growth, since it comigrates in NaDodSO4/polyacrylamide gel electrophoresis with a 12-kDa polypeptide that is continuously present in a regenerative system. In addition, there were injury-induced changes in the polypeptides of the nerve that were independent of treatment with conditioned medium and were correlated with nerve maturation. The most prominent changes of this type were in 18-kDa and 25-kDa polypeptides whose levels were reduced after injury and were found to be correlated with the nerve maturation (myelination) state.
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Szaro BG, Loh YP. Changes in axonal transport and glial proteins during optic nerve regeneration in Xenopus laevis. Curr Top Dev Biol 1987; 21:217-54. [PMID: 2443306 DOI: 10.1016/s0070-2153(08)60139-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- B G Szaro
- Laboratory of Neurochemistry and Neuroimmunology, National Institute of Child Health and Human Development, Bethesda, Maryland 20892
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Schwartz M. Molecular and cellular aspects of nerve regeneration. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1987; 22:89-110. [PMID: 2445526 DOI: 10.3109/10409238709083737] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Injury of an axon leads to at least four independent events, summarized in Figure 1: first, deprivation of the nerve cell body from target-derived or mediated substances, which leads to a derepressed or a permissive state; second, disruption of anterograde transport, with a resultant accumulation of anterogradely transported molecules; third, environmental response with possible consequent changes in constituents of the extracellular matrix and substances secreted from the surrounding cells; and fourth, appearance of growth inhibitors and modified protease activity. It seems that the first three of these events are obligatory, but not sufficient, i.e., they lead to a growth state only if the cell body is able to respond to the injury-induced signals from the environment (a and b). The regenerative state is characterized by alterations in protein synthesis and axonal transport and by sprouting activity. The subsequent elongation of the growing fibers depends on a continuous supply of appropriate growth factors. These factors are presumably anchored to the appropriate extracellular matrix that serves as a substratum for elongating fibers. It should be mentioned that the proliferating nonneuronal cells have a conducive effect on regeneration by forming a scaffold for the growing fibers. Accordingly, the lack of regeneration may stem from a deficiency in the ability of glial cells to provide the appropriate soluble components or from insufficient formation of extracellular matrix. In this respect, one may consider regeneration of an injured axon as a process which involves regeneration of both the nonneuronal cells and the supported axons. The regeneration of glial cells may fulfill the rules which are applied to regeneration of any other proliferating tissue. Furthermore, the processes of regeneration in the axon and the glial cells are mutually dependent. Perhaps the triggering factors provided by the nonneuronal cells affect the nonneuronal cells themselves by modulating their postlesion gliosis and thereby inducing their appropriate activation. In such a case, regeneration of nonneuronal cells may resemble an autocrine type of regulation that exists also during ontogeny. The growth regulation is shifted back to the paracrine type upon neuronal maturation or cessation of axonal growth. When the elongating fibers reach the vicinity of the target organ, they are under the influence of the target-derived factors, which guide the fibers and eventually cease their elongation.
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Affiliation(s)
- M Schwartz
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
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Mizrachi Y, Rubinstein M, Kimhi Y, Schwartz M. A neurotrophic factor derived from goldfish brain: characterization and purification. J Neurochem 1986; 46:1675-82. [PMID: 3517229 DOI: 10.1111/j.1471-4159.1986.tb08484.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Previous studies carried out in our laboratory have demonstrated that goldfish brain contains substances that promote neurite extension from regenerating retinae in culture. Fractionation of the brain extract by molecular sieving chromatography revealed the presence of several molecular species, including two peaks that have neurotrophic activity, representing low-molecular-weight substances. One peak was eluted (P-a) with an apparent molecular weight of about 13 kDa and was designated substratum neurite extension factor (SNEF) because it retained its neurotrophic activity when adsorbed onto the substratum. This recovered Sephadex fraction (P-a) when applied in vivo intraocularly caused an earlier capacity of the corresponding retinae to sprout in vitro. Thus, at 3 and 5 days after injury the neuritic growth indices from the factor-treated retinae were of 0.9 +/- 0.2 and 2.8 +/- 0.5, respectively, as compared with indices of 0.3 +/- 0.1 and 0.9 +/- 0.2, respectively, in retinae of injured but nontreated nerves. The factor was further purified by two steps of HPLC (ion exchange followed by reversed phase). The results showed that it is an acidic glycoprotein with an apparent molecular weight of 10 kDa.
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Oorschot DE, Jones DG. Effect of cytosine arabinoside on the composition of the nonneuronal cell population in cerebral explants. Exp Neurol 1986; 92:404-12. [PMID: 3956670 DOI: 10.1016/0014-4886(86)90092-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Rat cortical explants were cultured in the presence or absence of the mitotic inhibitor cytosine arabinoside to determine whether or not it affects the composition of the nonneuronal cell population within the outgrowth zone. Ultrastructural morphometric analysis of the incidence of fibroblasts, fibrous astrocytes, and protoplasmic astrocytes-epithelial cells at 18 days in vitro, revealed statistically significant decreases in the incidence of fibroblasts and fibrous astrocytes in the explants treated with the inhibitor compared with control explants. Coupled with earlier findings of enhanced neurite outgrowth and decreased nonneuronal cell proliferation that follows such treatment, it appears that cytosine arabinoside may potentiate neurite outgrowth by altering the composition, as well as the number, of nonneuronal cells in the outgrowth zone. These data indicate that fibroblasts and fibrous astrocytes may limit the regenerative response of severed axons in the mammalian central nervous system.
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Oorschot DE, Jones DG. Non-neuronal cell proliferation in tissue culture: implications for axonal regeneration in the central nervous system. Brain Res 1986; 368:49-61. [PMID: 3513901 DOI: 10.1016/0006-8993(86)91041-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A tissue culture model has been developed to examine the hypothesis that proliferating non-neuronal cells may constitute a physical and/or chemical barrier to regenerating neurons in the central nervous system. Explants from the sensorimotor cortex of 20-day-old fetal rats were cultured in serum medium (control) or serum medium containing 10(-5) M cytosine arabinoside (AraC), a mitotic inhibitor, for varying periods: 2-10, 4-12, 4-10, 4-8 and 4-7 days in vitro (DIV). The center and outgrowth zone of the explants were examined by phase-contrast microscopy at varying intervals between 3 and 18 DIV. The extent of central degeneration was greatest in explants treated with AraC from 2 DIV, and was least in the 4-7 day treated group in which only minimal degeneration was evident at 13 and 18 DIV. In the outgrowth zone at 18 DIV non-neuronal cell proliferation was controlled in the 4-10 day treated explants, although this was accompanied by extensive degeneration of neurites. Further examination of neurite viability, using a neurite viability ratio, revealed that degeneration was first evident at 6 DIV in the 2-10 day treated explants, but not until 9 or 13 DIV in any of the explants exposed to AraC from 4 days onwards. There was minimal degeneration in the 4-7 day treated explants. Electron microscopic examination revealed the presence of atypical inclusions in non-neuronal cells of 4-8 day treated explants, suggesting that the cytotoxic effect of AraC may be due to a disturbance in lipid and/or ganglioside metabolism. Quantitative electron microscopic analysis of the outgrowth zone at 18 DIV revealed a significant increase in the summated area of neuronal tissue (from 7 to 18 microns2/100 microns2) and a decline in the summated area of non-neuronal cells (from 83 to 61 microns2/100 microns2) for explants treated with AraC from 4 to 7 DIV compared to control. Diminishing the potential of non-neuronal cells to act as a barrier by controlling their proliferation may, therefore, be of importance in enhancing the regenerative response of central neurons.
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Schwartz M, Belkin M, Harel A, Solomon A, Lavie V, Hadani M, Rachailovich I, Stein-Izsak C. Regenerating fish optic nerves and a regeneration-like response in injured optic nerves of adult rabbits. Science 1985; 228:600-3. [PMID: 3983646 DOI: 10.1126/science.3983646] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Regeneration of fish optic nerve (representing regenerative central nervous system) was accompanied by increased activity of regeneration-triggering factors produced by nonneuronal cells. A graft of regenerating fish optic nerve, or a "wrap-around" implant containing medium conditioned by it, induced a response associated with regeneration in injured optic nerves of adult rabbits (representing a nonregenerative central nervous system). This response was manifested by an increase of general protein synthesis and of selective polypeptides in the retinas and by the ability of the retina to sprout in culture.
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Solomon A, Belkin M, Hadani M, Harel A, Rachailovich I, Lavie V, Schwartz M. A new transorbital surgical approach to the rabbit's optic nerve. J Neurosci Methods 1985; 12:259-62. [PMID: 3982074 DOI: 10.1016/0165-0270(85)90009-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This work describes a surgical approach which establishes the rabbit's visual system as an experimental model for studying CNS regeneration. Using this model, the optic nerve, its cell bodies, and the axons, are easily accessible through an orbital approach, without the need for craniotomy and brain retraction. This surgical approach allows transplantation and 'wrap around' implantations of nerve segments from xenogeneic and syngeneic systems and diffusible substances derived from them, respectively. Furthermore, it enables studies aimed at determining deficiencies in mammalian CNS and investigating methods of augmentating mammalian CNS regeneration.
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Hadani M, Harel A, Solomon A, Belkin M, Lavie V, Schwartz M. Substances originating from the optic nerve of neonatal rabbit induce regeneration-associated response in the injured optic nerve of adult rabbit. Proc Natl Acad Sci U S A 1984; 81:7965-9. [PMID: 6595671 PMCID: PMC392274 DOI: 10.1073/pnas.81.24.7965] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We have recently shown that cell bodies of an injured optic nerve of adult rabbit can be induced to express regeneration-associated response by external signals derived from nonneuronal cells of regenerating nerves of lower vertebrates. In this study it is shown that even substances derived from a nonregenerating mammalian system also can trigger such a regenerative response. Thus, substances derived from intact nerves of neonatal rabbits and of adult rabbits, to a lesser extent, were active in triggering a regeneration-associated response, whereas substances derived from injured nerves of adult rabbit were not. However, if subsequent to the injury the nerve was implanted with silicone tube containing medium conditioned by neonatal optic nerves, the substances derived from the implanted injured nerve were active. Thus, it appears that the ability of a periaxonal environment to provide triggering substances correlates with axonal growth. Therefore, we named these substances "growth-associated triggering factors" (GATFs). It is suggested that mammalian cells are unable to express a regenerative response after an injury due to the failure of their nonneuronal cells to produce regeneration-triggering substances. This disability may be circumvented by an appropriate implantation procedure.
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Abstract
Goldfish retinae deprived of their target by tectal ablation showed characteristics of regeneration, such as sprouting activity in culture and changes in protein synthesis. These features resemble changes occurring in regenerating retinae of optic nerves which were subjected only to crush injury. Retinae of tectal ablated nerves maintained their ability to sprout in culture longer than retinae of crushed-injured optic nerves. This may indicate a possible absence of the machinery which regulates growth termination as reflected in this case, by the enduring growth activity in culture. Among the changes in protein synthesis which occurred in retinae following either tectal ablation or crush injury, the most pronounced were in tubulin and in some other polypeptides of the following molecular weights: 46-49, 65 and 74 kdalton. Results are discussed with respect to the possible role of the target in initiating regeneration upon disconnection of the nerve, and in terminating growth upon reconnection.
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