The secretory vesicle in living Paramecium is acidic.
In Paramecium, secretory proteins are packaged within membrane-bounded vesicles in a condensed form. This form expands when the proteins are released. We have now determined that a proton gradient is present in the secretory vesicles of living Paramecium. Acridine Orange, used as an in vivo indicator of acidic compartments, stained the secretory vesicles in both wild-type and mutant cells. Addition of the two agents that dissipate proton gradients (protonophores), namely, 2,4-dinitrophenol (DNP) and carbonylcyanide m-chlorophenylhydrazone (CCCP), eliminated this staining. Washed cells re-established their intravesicular acidity. Effects of sodium azide on vesicular acidity suggest that proton transport in these vesicles involves an ATP-dependent mechanism.
Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461.
G R
GR
Busch
B H
BH
Satir
D000165:Acridine Orange; D000818:Animals; D015388:Organelles / Q000648:ultrastructure*; D010247:Paramecium / Q000648:ultrastructure*
D000165:Acridine Orange