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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 3911

R.R. Weik and D.T. John; Preparation and Properties of Mitochondria from Naegleria gruberi. J.Protozool. 26(2):311-318, 1979

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Whole cell respiration rates were measured polarographically for Naegleria gruberi during growth in agitated cultures. Log growth phase amebae consumed 80 ng atoms O/min/mg cell protein. At stationary phase, respiration rate decrease 4-fold. Intact mitochondria were isolated from N. gruberi and their oxidative and phosphorylative capacities were studied polarographically. As with the mammalian system, the mitochondria oxidized succinate and NAD-linked substrates, but unlike rat liver mitochondria, those from the protozoan rapidly oxidized citrate and NADH. The rates of substrate oxidation were ADP-dependent, with ADP:O ratios equalling ~2.8 for NAD-linked substrates and ~2.2 for succinate. The respiratory control ratios, 2 to 4 for 11 substrates, were dependent on Pi, Mg2+, and serum albumin. Potassium cyanide, azide, malonate, and rotenone inhibited electron transport the same way as that of the mammalian system; however, amytal inhibited both glutamate and succinate respiration. Pentachlorophenol, DNP, and bilirubin uncoupled oxidation from phosphorylation. Difference spectra of oxidized and dithionite-reduced mitochondria had distinct absorption bands of flavins and of c-, b- and a-type cytochromes.