Na,K-ATPase and V-ATPase in ovarian follicles of Drosophila melanogaster.
Uncovering the cause and meaning of bioelectric phenomena in developing systems requires investigations of the distribution and activity of ion-transport mechanisms. In order to identify and localize ion pumps in ovarian follicles of Drosophila, we used immunofluorescence microscopy, immunoelectron microscopy, subcellular fractionation, immunoblots, and acridine-orange staining. We applied various antibodies directed against the Na,K-pump (Na,K-ATPase) and against vacuolar-type proton pumps (V-ATPase). During all phases of oogenesis, Na,K-ATPase were found in apical and lateral follicle-cell membranes and, during rapid follicle growth (beginning with stage 10), also in nurse-cell membranes and in the oolemma. V-ATPase were detected in various cytoplasmic vesicles and in yolk spheres and, beginning with stage 10, also in apical follicle-cell membranes and in the oolemma. Given these and earlier results, we propose that: 1) V-ATPase coupled to secondary active antiporters represent the ouabain-intensitive potassium pumps described previously; 2) both Na,K-ATPase and V-ATPase are involved in bioelectric phenomena as well as in osmoregulation and follicle growth, especially during stages 10-12; 3) organelle-associated V-ATPase play a role in vesicle acidification and in yolk processing; and 4) the channel-forming protein ductin is a component of both V-ATPase and gap junctions in ovarian follicles of Drosophila.
Institut für Biologie I (Zoologie), Universität Freiburg, Germany.
J
J
Bohrmann
B
B
Braun
D000818:Animals; D000911:Antibodies, Monoclonal; D001692:Biological Transport / Q000502:physiology; D004331:Drosophila melanogaster; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D017629:Gap Junctions / Q000201:enzymology / Q000648:ultrastructure; D019476:Insect Proteins / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D007425:Intracellular Membranes / Q000201:enzymology / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D009866:Oogenesis / Q000502:physiology; D006080:Ovarian Follicle / Q000201:enzymology* / Q000648:ultrastructure; D011188:Potassium / Q000378:metabolism; D011510:Proteolipids / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases
D000911:Antibodies, Monoclonal; D019476:Insect Proteins; D011510:Proteolipids; C082471:ductin; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium