Functional characterization of mitochondria isolated from the ancient gymnosperm Araucaria angustifolia

Mitochondria were isolated from embryogenic cell cultures of Araucaria angustifolia, an ancient gymnosperm. The mitochondria obtained oxidized NADH and succinate as respiratory substrates and were able to sustain a high transmembrane electrical potential. They were able to take up Ca2+ supported by substrate oxidation, sensitive to ruthenium red and dependent on membrane potential. The influx of the ion was Pi dependent and at least one efflux pathway was demonstrated by ruthenium red addition. The mitochondria also oxidized externally added NADH, and presented oxygen consumption insensitive to cyanide and sensitive to salicyl hydroxamic acid (SHAM) suggesting the presence of external NADH dehydrogenase and alternative oxidase (AOX), respectively. Besides, mitochondria were uncoupled, in the absence of BSA, by the addition of oleic acid suggesting the presence of the plant uncoupling mitochondrial protein.