High-resolution electron microscopy is integrated with physicochemical methods in order to investigate the following preparations of the giant nerve fibers of the squid (Loligo pealii L.): (1) Thin sections of fibers fixed in four different fixatives; (2) fresh axoplasm stained negatively in solutions of different pH and composition; (3) chemically isolated threadlike elements of the axoplasm. A continuous, three-dimensional network can be identified in all these preparations of the axoplasm. The network is composed of coiled or looped unit-filaments ∼30 A wide. The unit-filaments are intercoiled in strands ∼ 70–250 A wide. The strands are oriented longitudinally in the axoplasm, often having a sinuous course and cross-associations. Microtubules are surrounded by intercoiled unit-filaments and filamentous strands. Calcium ions cause loosening and disintegration of the network configuration. UO2++ ions of a 1% uranyl acetate solution at pH 4.4 display a specific affinity for filamentous protein structures of the squid giant nerve fiber axoplasm, segregating the filamentous elements of the axoplasm in a coiled, threadlike preparation. The uranyl ions combine probably with the carboxyl groups of the main amino acids of the protein—glutamic and aspartic acids. It is proposed that by coiling/decoiling and folding/unfolding of the unit-filaments, shifts in physicochemical properties of the axoplasm are maintained.
Article| December 01 1969
CONFIGURATION OF A FILAMENTOUS NETWORK IN THE AXOPLASM OF THE SQUID (LOLIGO PEALII L.) GIANT NERVE FIBER
From the Department of Histology and Embryology, Faculty of Medicine, University of Ottawa, Ottawa, Canada, and the Marine Biological Laboratory, Woods Hole, Massachusetts 02543.
The author's present address is the Institute of Neurobiology, Faculty of Medicine, University of Göteborg, Göteborg, Sweden
Received: March 20 1969
Revision Received: July 29 1969
Online Issn: 1540-8140
Print Issn: 0021-9525
Copyright © 1969 by The Rockefeller University Press
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J. Metuzals; CONFIGURATION OF A FILAMENTOUS NETWORK IN THE AXOPLASM OF THE SQUID (LOLIGO PEALII L.) GIANT NERVE FIBER . J Cell Biol 1 December 1969; 43 (3): 480–505. doi: https://doi.org/10.1083/jcb.43.3.480
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