EFFECT OF OXYGEN ON END-PRODUCTS OF GLYCOLYSIS IN RANGIA CUNEATA

1. 1. The investigation reported here deals with the effect of oxygen on the utilization of U-14C-glucose by the clam Rangia cuneata, in vivo and in vitro. 2. 2. In vivo, Rangia utilizes oxygen for limited purposes, namely to oxidize NADH and to a minor extent succinate as indicated by the ratio of alanine to succinate produced over a period of 72 hr. 3. 3. When isolated mantle is incubated with U-14C-glucose in a medium saturated with oxygen, the glucose is converted nearly quantitatively into alanine while succinate formation is suppressed. The high yield of alanine is a strong indication that pyruvate is poorly oxidized or not oxidized at all under optimal aerobic conditions. Succinate fails to form under these conditions as the redox pair NADH/NAD is in a more oxidized state. 4. 4. Isolated mantle mitochondria do not oxidize pyruvate, malate or α-ketoglutarate as determined with the oxygen electrode. NADH and succinate are oxidized to some extent. When a large excess of cytochrome-c is added there is stimulation of oxygen uptake but only with NADH and succinate can it be considered significant. 5. 5. All the results are in harmony with the contention that Rangia and perhaps other bivalves satisfy their energy requirement mainly by anaerobic reactions utilizing oxygen when available only to a limited extent. © 1969.