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. 1974 Apr 1;61(1):146–155. doi: 10.1083/jcb.61.1.146

CALCIUM-CONTAINING ELECTRON-DENSE STRUCTURES IN THE AXONS OF THE SQUID GIANT SYNAPSE

D E Hillman 1, R Llins 1
PMCID: PMC2109256  PMID: 4819304

Abstract

Following the Oschman and Wall technique, electron-dense structures (EDS) were found on unstained, unosmicated membranes of squid giant synapse axons. These densities contain high concentrations of calcium and phosphorus as identified by energy dispersive X-ray analysis. Based on the signal strength, the quantity is significantly greater than that of other regions of the membrane or tissue spaces. The calcium EDS occur as plaques or globules along the axonic membrane, and small globules are found between sheath cell processes. EDS also occur at the synaptic site. These densities were correlated with the opacity change seen in giant axons. It is proposed that these structures represent sites where the calcium-binding protein found by other investigators has become nearly saturated with calcium.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Alemà S., Calissano P., Rusca G., Giuditta A. Identification of a calcium-binding, brain specific protein in the axoplasm of squid giant axons. J Neurochem. 1973 Mar;20(3):681–689. doi: 10.1111/j.1471-4159.1973.tb00028.x. [DOI] [PubMed] [Google Scholar]
  2. Baker P. F., Crawford A. C. Mobility and transport of magnesium in squid giant axons. J Physiol. 1972 Dec;227(3):855–874. doi: 10.1113/jphysiol.1972.sp010062. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Baker P. F. Transport and metabolism of calcium ions in nerve. Prog Biophys Mol Biol. 1972;24:177–223. doi: 10.1016/0079-6107(72)90007-7. [DOI] [PubMed] [Google Scholar]
  4. Blaustein M. P., Hodgkin A. L. The effect of cyanide on the efflux of calcium from squid axons. J Physiol. 1969 Feb;200(2):497–527. doi: 10.1113/jphysiol.1969.sp008704. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Ebashi S., Endo M., Otsuki I. Control of muscle contraction. Q Rev Biophys. 1969 Nov;2(4):351–384. doi: 10.1017/s0033583500001190. [DOI] [PubMed] [Google Scholar]
  6. HODGKIN A. L., KATZ B. The effect of calcium on the axoplasm of giant nerve fibers. J Exp Biol. 1949 Oct;26(3):292-4, pl. doi: 10.1242/jeb.26.3.292. [DOI] [PubMed] [Google Scholar]
  7. HODGKIN A. L., KEYNES R. D. Movements of labelled calcium in squid giant axons. J Physiol. 1957 Sep 30;138(2):253–281. doi: 10.1113/jphysiol.1957.sp005850. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Harvey A. M., Macintosh F. C. Calcium and synaptic transmission in a sympathetic ganglion. J Physiol. 1940 Jan 15;97(3):408–416. doi: 10.1113/jphysiol.1940.sp003818. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Heuser J. E., Reese T. S. Evidence for recycling of synaptic vesicle membrane during transmitter release at the frog neuromuscular junction. J Cell Biol. 1973 May;57(2):315–344. doi: 10.1083/jcb.57.2.315. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Hoyle G., McNeill P. A., Selverston A. I. Ultrastructure of barnacle giant muscle fibers. J Cell Biol. 1973 Jan;56(1):74–91. doi: 10.1083/jcb.56.1.74. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. KATZ B., MILEDI R. THE EFFECT OF CALCIUM ON ACETYLCHOLINE RELEASE FROM MOTOR NERVE TERMINALS. Proc R Soc Lond B Biol Sci. 1965 Feb 16;161:496–503. doi: 10.1098/rspb.1965.0017. [DOI] [PubMed] [Google Scholar]
  12. KEYNES R. D., LEWIS P. R. The intracellular calcium contents of some invertebrate nerves. J Physiol. 1956 Nov 28;134(2):399–407. doi: 10.1113/jphysiol.1956.sp005652. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Katz B., Miledi R. Ionic requirements of synaptic transmitter release. Nature. 1967 Aug 5;215(5101):651–651. doi: 10.1038/215651a0. [DOI] [PubMed] [Google Scholar]
  14. Katz B., Miledi R. Tetrodotoxin-resistant electric activity in presynaptic terminals. J Physiol. 1969 Aug;203(2):459–487. doi: 10.1113/jphysiol.1969.sp008875. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Kirpekar S. M., Misu Y. Release of noradrenaline by splenic nerve stimulation and its dependence on calcium. J Physiol. 1967 Jan;188(2):219–234. doi: 10.1113/jphysiol.1967.sp008135. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Kirpekar S. M., Wakade A. R. Release of noradrenaline from the cat spleen by potassium. J Physiol. 1968 Feb;194(3):595–608. doi: 10.1113/jphysiol.1968.sp008427. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Llinás R., Blinks J. R., Nicholson C. Calcium transient in presynaptic terminal of squid giant synapse: detection with aequorin. Science. 1972 Jun 9;176(4039):1127–1129. doi: 10.1126/science.176.4039.1127. [DOI] [PubMed] [Google Scholar]
  18. Miledi R., Slater C. R. The action of calcium on neuronal synapses in the squid. J Physiol. 1966 May;184(2):473–498. doi: 10.1113/jphysiol.1966.sp007927. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Miledi R. Transmitter release induced by injection of calcium ions into nerve terminals. Proc R Soc Lond B Biol Sci. 1973 Jul 3;183(1073):421–425. doi: 10.1098/rspb.1973.0026. [DOI] [PubMed] [Google Scholar]
  20. Oschman J. L., Wall B. J. Calcium binding to intestinal membranes. J Cell Biol. 1972 Oct;55(1):58–73. doi: 10.1083/jcb.55.1.58. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Spurr A. R. A low-viscosity epoxy resin embedding medium for electron microscopy. J Ultrastruct Res. 1969 Jan;26(1):31–43. doi: 10.1016/s0022-5320(69)90033-1. [DOI] [PubMed] [Google Scholar]
  22. Tasaki I., Watanabe A., Lerman L. Role of divalent cations in excitation of squid giant axons. Am J Physiol. 1967 Dec;213(6):1465–1474. doi: 10.1152/ajplegacy.1967.213.6.1465. [DOI] [PubMed] [Google Scholar]

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