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Journal of Cell Science, Vol 94, 127-134, Copyright © 1989 by Company of Biologists
Submitted on April 21, 1989
Accepted on May 31, 1989
1 Laboratoire de Biochimie (UA 1130 du CNRS), Fédération des Laboratoires de Biologie
2 Laboratoire de Biochimie (UA 1130 du CNRS), Fédération des Laboratoires de Biologie;Department of Biological Sciences, University of Windsor, Ontario, Canada
3 DRF/SPh/Résonance Magnétique en Biologie et Médecine, Centre d'Etudes Nucléaires de Grenoble, 85 X, 38041 Grenoble Cedex, France
Author for correspondence
Axenic growth of amoebae of the slime mold Dictyostelium discoideum was found to be reversibly inhibited by vanadate. Pinocytosis, when measured with fluorescein-labeled dextran as a fluorescent fluid-phase marker was strongly inhibited by vanadate. Inhibition was observable at vanadate concentrations as low as 0*2 mM. Sucrose entry through pinocytosis induced massive cell vacuolation and this effect was blocked by vanadate. Secretion of soluble lysosomal enzymes is another aspect of membrane traffic in Dictyostelium. Secretion of two typical lysosomal enzymes, acid phosphatase and hexosaminidase, was inhibited by concentrations of vanadate in the same range as for pinocytosis inhibition. Vanadate also prevented the morphogenetic developmental program that follows nutrient starvation. In contrast, vanadate did not prevent heat-induced spore germination. Vanadate had no significant action on the intracellular nucleoside triphosphate level or on the cytosolic pH. It is suggested that the particular effect of vanadate in Dictyostelium is to inhibit the fusion of endosomes with lysosomes. Our results provide a probe that could be useful to clarify the mechanisms of endocytosis.
Key words: Dictyostelium amoebae, vanadate, endocytosis, multicellular development, spore germination
Submitted on April 21, 1989
Accepted on May 31, 1989
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