J Gautron's research while affiliated with Institut de France, Académie des sciences and other places

Publications (20)

Article
—Au cours d'une période de stimulation, la réponse électrophysiologique de l'organe électrique évolue en trois phases successives: décroissance, palier, décroissance. Le taux d'acétylcholine (ACh) totale baisse durant la première décroissance. Il augmente pendant le palier, pouvant atteindre et même dépasser sa valeur initiale. Une nouvelle baisse...
Article
Résumé— L'acétylcholine ‘libre’ et ‘liée’ a été mesurée avant et après stimulation de l'organe électrique de la Torpille in vivo ou in vitro, sur des tranches de tissu incubées dans une solution physiologique. Des potentiels de plaque miniatures peuvent être enregistrés. Des déharges d'une amplitude atteignant 30 V ont été obtenues après stimulatio...
Article
Résumé— L'acètylcholine a été localisée au niveau d'une fraction de vésicules synaptiques isolée à partir de l'organe électrique; le taux d'acétylcholine est fonction de la pression osmotique du milieu. La choline-acétyltransfèrase (EC 2.3.1.6) n'est pas associée à cette fraction. Les distributions sont comparées à celles de diverses enzymes.Abstra...
Article
—Des séparations sur gel de polyacrylamide ont permis d'établir la distribution électrophorétique des protéines, de l'incorporation d'acides aminés et de l'acétylcholinestérase (AChE; EC 3.1.1.7) du ganglion sympathique au repos et stimulé. Une étude conjointe d'histochimie ultrastructurale a montré que l'essentiel de l'activité acétylcholinestéras...
Article
Abstract— In sucrose gradient centrifugation, acetylcholinesterase (AChE, EC 3.1.1.7.) from the rat superior cervical ganglion (SCG) has been found to contain four molecular forms, characterized by their sedimentation coefficients (4 S, 6.5 S, 10 S and 16 S). Homogenization of the ganglia in various media showed that the 4 S enzyme was readily solu...
Article
Section of the preganglionic nerve of the superior cervical ganglion of the Rat produced a decrease followed by an increase of the acetylcholinesterasic activity. By cytochemical study it was possible to localize, from the seventh day after denervation, a strong acetylcholinesterase activity in the glial cells which lay close to the pericarya of th...
Article
The electrophoretic patterns of proteins, radioactivity and acetylcholinesterase (AChE, EC 3.1.1.7.) extracted by water or Triton X-100 from resting and stimulated sympathetic ganglia were determined by analysis on polyacrylamide gels. A concomitant study by ultrastructural histochemistry showed that the bulk of the acetylcholinesterase activity of...
Article
The chapter discusses the cellular and subcellular localization of acetylcholine in electric organs with the help of the studies of vesicles conducted on guinea pig or rat brain and pure cholinergic tissues, such as neuromuscular and nerve electroplaque junctions. It describes the results of these studies. The studies conducted with muscle and elec...

Citations

... The large granular vesicles may be present close to the junctional zone, but there are also clusters of clear synaptic vesicles (40 nm in average diameter). The tryptaminergic nerve endings of the ABRM thus resemble those described by Taxi and Gautron (1969) in the heart of Aplysia, or by Pentreath (1976) in the ganglionic neuropile of Helix. The morphological variability of the vesicular content is a rule, and may be explained by sequential physiological changes in serotonin packaging (see Shkolnik and Schwartz 1980). ...
... The indisputable evidence appeared in 1968, when IsraEl and his colleagues isolated cholinergic vesicles from the Torpedo electric organ. This pure fraction of vesicles was associated with as much as 140 nmol of ACh per g of original tissue, i.e. about 40 70 of the ACh measured in the homogenate (IsraEl et al., 1968 IsraEl and Gautron, 1969;). The condition which permitted the recovery of such a high amount of vesicles filled with their ACh was the use of fractionation media containing NaCI in addition to sucrose in order to get an iso-osmotic solution as compared to the plasma of elasmobranch fishes, without having too high a density as in the case of the previous experimental attempts (Sheridan et al., 1966). ...
... The enzyme responsible for ACh synthesis, choline acetylase, discovered by Nachmansohn and Machado (1943), and which was later called choline acetyltransferase, is not contained within synaptic vesicles. It behaves as a soluble cytoplasmic component in fractionation experiments performed with various preparations from many animal species (Fonnum, 1966;IsraEl, 1970;IsraEl et al., 1970;Marchbanks and IsraEl, 1972). The consequence is that at least the newly-synthetized transmitter must be cytoplasmic. ...
... Exchange of compounds or ions between the bathing medium and the core of the prisms can only occur by diffusion. This requires about 1 h for a compound like bafilomycin in a 4 mm prism (Dunant et al. 1972). Excised prisms were placed on a small piece of nylon cloth under continuous superfusion with the saline medium (Fig. 1A). ...
... Instead, AChE is present mainly as the globular form G4, which is predominantly located in the endoplasmic reticulum of neurons ( Figure 2C), from where it is secreted in the extracellular space [83]. In denervated ganglia, AChE activity is sharply reduced in parallel with the disruption of the neuron's endoplasmic reticulum cisternae [84]. These changes following denervation might suggest that AChE is one of the proteins whose synthesis is regulated by activity-induced trans-synaptic mechanisms [85,86]. ...
... It was a surprise to find that modifications of the ACh stores, far from being a simple decline, exhibited large and undamped oscillations. Another unexpected finding was that the ACh contained in synaptic vesicles behaved as a relatively stable pool which was not available for immediate release on stimulation (Dunant et al., 1972(Dunant et al., , 1974(Dunant et al., , 1977Suszkiw et al., 1978). ...
... Crude preparations of electric organ homogenate were available, though very heterogeneous. To simplify the system, Changeux introduced a new approach based upon the electron microscopy of membrane fragments purified from E. electricus electric tissue (on the basis of their high content of acetylcholinesterase) which revealed that the majority of the fragments reseal into closed vesicles or "microsacs" [20]. As shown by Kasai and Changeux [21] such microsacs retain permeant ions like radioactive Na + or K + and using a simple filtration technique nAChR agonists caused an increase of the rate of ion flux while the "apparent volume" of the microsacs population did not change ( Figure 3). ...
... pieces of excised tissue, and by Zimmerman and Whittaker (21), who carried out in vivo stimulation. No loss of vesicles was observed when excised tissue was stimulated (8). On the other hand, in vivo stimulation produced a progressive fall in ACh, ATP, total nucleotide, and vesicle protein in the isolated vesicles, along with an eventual 50% loss of vesicle profiles in fatigued nerve terminals (21). ...
... The presence of ACh in muscle fibres is a constant finding in all species investigated. Its concentration is apparently lower than in nerve endings but this pool may contribute to the so-called non-quantal transmitter release which is described in Section 2.2 (Bhatnagar and McIntosh, 1960; Mitchell and Silver, 1963; Israel, 1970; Miledi et al., 1977 Miledi et al., , 1982 Miledi et al., , 1983 Kriebel et al., 1978; Rose et aL, 1977; Dolezal and Tu~ek, 1983). The presence of ACh in muscle fibres has been explained only recently. ...