Studies on the mechanism of axoplasmic transport in the crayfish cord

Fernández, Hugo L.; Huneeus, Francisco; Davison, Peter F.

doi:10.1002/neu.480010404

Cited by 99 publications

(18 citation statements)

References 19 publications

(10 reference statements)

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“…There are now several studies which show that low temperatures block or suppress the rate of axoplasmic transport (Fernandez et al, 1970;Grafstein et aL, z 972). It is not yet clear what the effect of blockage of transport will be on pre-terminal parts of the axon, but blockage induced by colchicine is known to cause reversible degeneration and transmission deficits at axon terminals (Cutnod et al,I972;Perisic and Cutnod,I972).…”

Section: Discussionmentioning

confidence: 97%

Induced hypothermia in peripheral nerve: Electron microscopic and electrophysiological observations

Basbaum

1973

J Neurocytol

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SummaryLocalized cooling of the cat sciatic nerve was achieved by application of a thermoelectric device to the exposed nerve at mid-thigh. The temperature of the nerve was maintained at 5°C for z h. Before, during, and after cooling, the response of the nerve to electrical stimulation was monitored, and compared with responses obtained in normothermic control preparations. In all cases, dropping the temperature of the nerve to 5°C resulted in total nerve block, and in all cases, function was restored when cooling stopped. Light and electron microscopic analysis of the cooled nerves revealed that despite functional recovery, a lesion affecting large myelinated axons developed over the course of 7 days. Both Wallerian degeneration and segmental demyelination occurred. Unmyelinated fibres were not affected.

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Section: Discussionmentioning

confidence: 97%

Induced hypothermia in peripheral nerve: Electron microscopic and electrophysiological observations

Basbaum

1973

J Neurocytol

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“…Such an energy-dependent process could act as a basis for microtubule-dependent motility. It is interesting in this regard that we have shown that colchicine blocks subunit flow and that it has also been found that colchicine blocks axonal transport even in cases in which it does not disrupt microtubules (Fernandez et al, 1970;Norstrom, 1975).…”

Section: K+/umentioning

confidence: 95%

Kinetic and steady-state analysis of microtubules in the presence of colchicine

Deery¹,

Weisenberg²

1981

Biochemistry

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The effects of colchicine on bovine brain microtubules under steady-state conditions have been studied by combined kinetic and equilibrium analysis. Colchicine induces an initially rapid rate of depolymerization when added to microtubules which are at steady state. The initial rate of disassembly follows the kinetics of colchicine binding to free tubulin. However, disassembly is incomplete, and a new steady-state concentration of microtubules is established provided that a sufficient concentration of colchicine-tubulin is present. When steady state is attained from the disassembly direction, colchicine decreases the formation the fraction of tubulin which is participating in the assembly reaction, without measurably changing the apparent critical concentration for polymerization. The extent of depolymerization of microtubules by colchicine is greater the lower the content of microtubule-associated proteins (MAPs). Microtubules at steady state in the presence of either colchicine or GDP do not exhibit subunit flow which occurs in microtubules at steady state in GTP. Colchicine-tubulin will stabilize microtubules in the presence of MAPs but will not support microtubule elongation. Microtubules at steady state in the presence of colchicine depolymerize upon dilution at about the same rate as untreated microtubules, and, in either case, disassembly appears to occur from both ends of the microtubule. These observations appear to be inconsistent with simple reversible assembly mechanisms but may be explained by a model based upon the cooperative interactions of MAP-tubulin oligomers.

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“…We have previously characterized the protein subunit of neurofilaments from squid but subsequent work has shown that this protein is chemically distinguishable from neurofilament protein from mammalian brain. Other studies by our collaborators have shown that sectioned cockroach (Smith, 1968) and crayfish (Fernandez, Huneeus and Davison, 1970;Fernandez, Burton and Samson, 1971) nerves do not contain typical neurofilaments; further unpublished ultrastructural investigations of negatively stained dispersions of crayfish and lobster axons failed to reveal neurofilameiits although microtubules were plentiful (Davison, 1968). Therefore, if some arthropods do not have neurofilaments, and the neurofilaments of other species are dis-119 tinguishable, it seems desirable to investigate these structures in greater detail and to compare the properties of the protein in different species.…”

Section: Introductionmentioning

confidence: 95%

The protein subunit of calf brain neurofilament

1974

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A preparation of the protein subunits from calf neurofilaments has been obtained. Axon segments from an homogenate of calf brain white matter have been concentrated by a subcellular fractionation procedure. After further steps to achieve a complete elimination of unbound lipid, the neurofilament protein was dissolved in 4M guanidine hydrochloride solutions. The neurofilalment subunit was the major constituent of the guanidine hydrochloride extracts; other proteins of higher molecular weight were eliminated by agarose gel filtration in urea solutions. Dialysis to solutions of low ionic strength allowed the reformation of fibril aggregates, some of which, under electron microscopy, resembled the original neurofilaments in morphology. The physical characteristics of the neurofilament subunit protein are reported and a preliminary amino acid analysis is given. The neurofilament protein is clearly distinguishable from actin and tubulin on physical and chemical grounds.

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Studies on the mechanism of axoplasmic transport in the crayfish cord

Cited by 99 publications

References 19 publications

Induced hypothermia in peripheral nerve: Electron microscopic and electrophysiological observations

Induced hypothermia in peripheral nerve: Electron microscopic and electrophysiological observations

Kinetic and steady-state analysis of microtubules in the presence of colchicine

The protein subunit of calf brain neurofilament

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