Relations between development and regeneration of tadpole spinal cord
- 48 Downloads
1. The developing spinal cords of bullfrogs and transected cords of stage IV tadpoles were subjected to two-dimensional gel electrophoresis and histological analysis. During development, the level of actin,α-tubulin orβ-tubulin in the 7–10th spinal segments increased with time and reached a maximum around stage XIII followed by a decrease, as shown from quantitative assay on protein spots of 2-dimensional gels of cord homogenates. In contrast, the level of 68 kD neurofilament subunit (NF68) was low in tadpoles but high in frog.
2. Following a complete transection made at the level of the 8th spinal segment, the cord tissue of the lesion zone degenerated; regeneration from each cut end then occurred, which lengthened for approximate 0.35 mm by 28 days after transection. The content of actin,α-tubulin andβ-tubulin in the cord within 1–2 mm of the transection site was elevated to 124–192% of control values 7–28 days post-transection, whereas NF68 declined to near non-detectable extent.
3. The regeneration of each cord stump included outgrowth of neuroepithelial cells and nerve fibers, reconstituting a newly regenerated cord segment. Ultrastructural examination revealed that features of the regrowth of fibers and guidance of neuroepithelial cells to the axonal growth resembled that seen in the developing cord. Thus the biochemical and morphological data support that the regeneration of the nervous system recaptulates its developmental events, providing evidence for molecular mechanisms underlying central axonal regeneration.
Key wordsCNS regeneration development ultrastructure 2-D gel electrophoresis cytoskeletal proteins
Unable to display preview. Download preview PDF.
- Bernstein, J. J., and Bernstein, M. E. (1969). Ultrastructure of normal regeneration and loss of regenerative capacity following teflon blockade in goldfish spinal cord.Exp. Neurol. 25:538–557.Google Scholar
- Bunge, M. B. (1986). The axonal cytoskeleton: its role in generating and maintaining cell form.Trends Neurosci. 9:477–482.Google Scholar
- Davis, B. M., Carlson, J. L., Goldstein, L. D., Anderson, M. C., and Simpson, S. B. Jr. (1989). Neurogenesis in naturally occurring spinal cord regeneration.Soc. Neurosci. Abst. 15:332.Google Scholar
- Forehand, C. J., and Farel, P. L. (1982). Anatomical and behavioral recovery from the effects of spinal cord transection: Dependence on metamorphosis in anuran larvae.J. Neurosci. 5:654–662.Google Scholar
- Hoffman, P. N., Griffin, J. W., Gold, B. G., and Price, D. L. (1985). Slowing of neurofilament transport and radial growth of developing nerve fibers.J. Neurosci. 11:2920–2929.Google Scholar
- Nordlander, R. H., and Singer, M. (1982). Morphology and position of growth cones in the developingXenopus spinal cord.Devel. Brain Res. 4:181–193.Google Scholar
- Piatt, J. (1955). Regeneration in the central nervous system of amphibia. In Windle, W. F. (ed.),Regeneration in the Central Nervous System, Thomas, Springfield, pp. 20–46.Google Scholar
- Riederer, B. M. (1990). Some aspects of the neuronal cytoskeleton in development.Eur. J. Neurosci. 3:1134–1145.Google Scholar
- Robinson, P. A., and Anderton, B. H. (1988). Neurofilament probes—a review of neurofilament distribution and biology.Rev. Neurosci. 2:1–40.Google Scholar
- Sims, R. T. (1962). Transection of the spinal cord in developingXenopus laevis.J. Embry. Exp. Morphol. 10:115–126.Google Scholar
- Taylor, A. C., and Kollros, J. J. (1946). Stages in the normal development ofRana pipiens larvae.Anat. Rec. 94:7–24.Google Scholar
- Yin, H. S., Chou, H. C., and Chiu, M. M. (1995). Changes in the microtubule proteins in the developing and transected spinal cord of the bullfrog tadpoles: Induction of MAP2c and enhanced levels of Tau and tubulin in regenerating central axons.Neurosci. 67:763–775.Google Scholar