Incorporation of Ortho [32p]phosphate Into the Subcellular Fractions of Developing Rat Brain*

The refinement of techniques for the isolation of the cytoplasmic fractions of rat brain has now made it possible to study more accurately the biochemical development and turnover of the various subcellular elements of the neuron. A previous communication (Abdel‐Latif and Abood, 1964) described enzymic studies with cytoplasmic constituents prepared from embryonic and neonatal rat brains by the technique of density gradient centrifugation. It was the object of the present study to examine, with the aid of ortho [32P]phosphate, the formation and turnover of the phospholipids, phosphoproteins, and other phosphate‐containing compounds of the various subcellular components of the rat brain at various stages of development. While several investigations have dealt with the incorporation of32P1 into the phospholipids of rat brain (Ansell, 1960; Davison and Dobbing, 1960; Ansell and Spanner, 1959; Rossiter, 1957; and Dziewiatkowski and Bodian, 1950) none has dealt with the incorporation into the phospholipids and phosphoproteins of the various subfractions, and very little work has been done on the turnover of well‐defined phospholipids in the developing brain.