The objective of this proposal is to study the mechanism of myelin formation and to determine the regulatory controls affecting myelin metabolism during development and adulthood. Studies on the turnover of phospholipids and sphingolipids have indicated that these lipids in myelin turn over at different rates. Apparent and relative turnover rates of individual proteins of purified myelin will be determined after intracerebral injection of radioactive precursors into adult and developing rats. Various studies have indicated that the site of synthesis of complex-lipids, such as phospholipids, sphingolipids and cholesterol, is in the endoplasmic reticulum (microsomes). It is not known how these lipids in myelin membranes are assembled. It is suggested that intra-cellular transport and/or exchange of newly synthesized lipid molecules can occur. 'Pulse-chase' experiments with rat brain slices and various precursors of phospholipids and sphingolipids, exchange of these lipids between isolated microsomes and myelin, 'myelin-like' and other subcellular membranes and isolation and identification of intermediary membranes would provide evidence for such a concept. Dissociated embryonic brain cell-cultures will be employed to study myelination and environmental factors affecting myelination. The regulation of phospholipid biosynthesis during brain development and myelination will be studied by measuring the characteristics of the enzymes and substrates pools. The biosynthesis of phosphatidylserine will be investigated in vivo. High performance liquid chromatography technique will be employed for the analysis of individual phospholipids in human amniotic and cerebrospinal fluids and blood. New methods will be developed for the antenatal diagnosis of respiratory distress syndrome, Neimann-Pick disease, anencephaly, etc. BIBLIOGRAPHIC REFERENCES: Jungalwala, F.B., Turel, R.J., Evans, J.E. and McCluer, R.H.: Sensitive analysis of ethanolamine and serine containing phosphoglycerides by high-performance liquid chromatography. Biochem J. 145 (1975) 517-526. Jungalwala, F.B., Evans, J.E. and McCluer, R.H.: High-performance liquid chromatography of phosphatidylcholine and sphingomyelin with detection in the region of 200 nm. Biochem J. 155 (1976) 55-60.