title: Ductin, a component of the V-ATPase, is developmentally regulated in Heliothis virescens midgut, and anti-ductin antibodies label lateral membranes.
abstract: We previously cloned from Heliothis virescens a 16-kDa protein that is homologous to other ductin sequences. We also reported its immunolocalization with a specific affinity-purified anti-peptide antibody in the midgut and Malpighian tubule of feeding larvae, and concluded that the cloned proteolipid encodes the V-ATPase proton-transporting subunit c from the V0 sector. We now present the immunolocalization of this protein in the midgut during the L4-L5 larval molt and early post-ecdysis into the fifth instar in H. virescens. The results show that the spatial expression of the 16-kDa protein is developmentally regulated. Labeling by anti-peptide antibody varies during the molt in the midgut goblet cell apical plasma membrane and the goblet cell apical valve. Epifluorescence and confocal microscopy revealed strong anti-ductin labeling in areas of cell-to-cell contact during the molt, and during early post-ecdysis into the fifth larval instar. The characteristic labeling pattern observed in areas of cell-to-cell contact is consistent with the claimed involvement of ductins in gap junctions. Conclusive evidence for the presence of the 16-kDa protein in areas of cell-to-cell contact in the midgut of feeding larvae is, however, lacking. V-ATPase regulation during the molt was also investigated by simultaneous immunohistochemistry with an anti-B subunit antiserum, a probe for the V1 sector.
authors.affiliation: Department of Entomology, University of California, Riverside, CA 92521, USA.
authors.forename: P V
authors.initials: PV
authors.lastname: Pietrantonio
authors.forename: S S
authors.initials: SS
authors.lastname: Gill
mesh_terms: D000818:Animals; D000906:Antibodies; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism; D004064:Digestive System / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D009036:Moths / Q000196:embryology / Q000201:enzymology / Q000378:metabolism*; D011510:Proteolipids / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases
chemical_list: D000906:Antibodies; D011510:Proteolipids; C082471:ductin; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases