A comparative study on vertebrate brain mitochondria

Brain mitochondria from catfish, frog, turtle, chicken and rat were studied after separation by differential centrifugation. It was found that per gram of brain: (1) The wet weight of mitochondria ranges from 225 mg in the frog to 472 mg in the rat; (2) The dry weight of mitochondria ranges from 36 mg in the frog to 80 mg in the rat; (3) The mitochondrial protein ranges from 15 mg in the frog to 32 mg in the rat; (4) The oxidative capacity of rat brain is 10 times that of catfish brain; (5) The number of mitochondria ranges from 18·8×10 10 in the frog to 33·2×10 10 in The rat. The corresponding values for the turtle and the chicken were in the order of: frog, turtle, chicken and rat. With the exception of the catfish, the average mitochondria for all the animals is strikingly similar with 1·69×10 −12 g wet weight, 0·27×10 −12 g dry weight and 0·11×10 −12 g protein.