Characteristic of mitochondrial nucleic acids obtained from calf brain gray and white matter.

The brain mitochondrial system is of a special interest because of the high concentration of mitochondria in the synaptic regions of neurons. Klee and Sokoloff (1965) have demonstrated the occurrence of protein synthesis in brain mitochondria. Campbell et al. (1966) have isolated two distinct cell-free protein synthesizing systeins from immature rat brain, one localized in purified ribosomes, the other in mitochondria. The participation of the mitochondrial synthesizing system in synaptosoma1 protein synthesis is still discussed (Barondes 1966, 1968, Morgan and Austin 1968). Recent studies lend support to the view that mitochondria posses a remarkable degree of autonomy; they appear to contain some of the information and apparatus for macromolecular biosynthesis and possibly for their own biogenesis (Nass 1967, Karol and Simpson 1968, Meyer and Simpson 1969). In our previous work (Borkowski et al. 1967, 1968) we have demonstrated the difference between nucleic acids obtained from the whole brain and liver mitochondria. I t is evident that the tissue of the central nervous system is morphologically heterogeneous. Therefore in this communication the experiments performed on two anatomically distinct parts of an adult brain have been described.