The objective of this research is to study the biochemical controls involved in the differenciation and development of lung tissue. Nutritional, hormonal and genetic factors will be analyzed using radioisotipic and immunochemical techniques. Since vitamin A is apparently involved in the differenciation of the lung epithelium, efforts will be made to elucidate the role of intracellular binding proteins for retinol and a separate one for retinoic acid in lung metabolism. These proteins have been recently characterized in this laboratory. Striking alterations in the levels of the binding proteins were observed during lung maturation. It will be attempted to identify the stimuli which influence the levels of the binding proteins in the lung. The properties of the lung chromatin and its components during ontogeny of the lung as well as interaction of retinol, retinoic acid and their respective cellular binding proteins with the components of the lung nucleus will be studied. Using an immunochemical method developed in this laboratory in conjunction with chemical procedures the changes in the structure and function of chromatin will be studied during perinatal development of the lung.