title: Oxidation of External NAD(P)H by Mitochondria from Taproots and Tissue Cultures of Sugar Beet (Beta vulgaris).
abstract: The present study compares the exogenous NAD(P)H oxidation and the membrane potential ([delta][psi]) generated in mitochondria isolated from different tissues of an important agricultural crop, sugar beet (Beta vulgaris}. We observed that mitochondria from taproots, cold-stored taproots, and in vitro-grown tissue cultures contain a functional NADH dehydrogenase, whereas only those isolated from tissue cultures displayed a functional NAD(P)H dehydrogenase. It is interesting that the NADH-dependent [delta][psi] of mitochondria from cold-stored taproots and from tissue cultures was not affected by free Ca2+ ions, whereas free Ca2+ was required for the mitochondrial NADPH oxidation by in vitro-grown cells and cytosolic NADH oxidation by mitochondria from fresh taproots. A tentative model accounting for the different response to Ca2+ ions of the NADH dehydrogenase in mitochondria from cold-stored taproots and tissue cultures of B. vulgaris is discussed.
authors.affiliation: Department of Biology, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy (M.Z., D.Z.).
authors.forename: M.
authors.initials: M
authors.lastname: Zottini
authors.forename: G.
authors.initials: G
authors.lastname: Mandolino
authors.forename: D.
authors.initials: D
authors.lastname: Zannoni