Dr. Schmidt is one of the few researchers in the area of organelle biosynthesis that is addressed the role of past - transcriptional processes in the establishment of the phenotypes of chloroplasts. A complete overview on regulation of chloroplast gene expression cannot be achieved without a thorough understanding of these events. He has, in the last grant period, made some significant findings. The processes involved in maturations of proteins into chloroplasts have been characterized. The extent to which photosynthetic protein accumulation is regulated at the posttranscriptional level by selective chloroplasts proteases has been investigated. Additionally, analyses of translational versus post-translational regulatory processes that mediate the stoichiometric accumulation of RuBPcase, photosystems I and II, and the light harvesting complexes of thylakoid membranes have been carried out. Future plans are logical extensions of this work. Five publications have resulted from these investigations. Dr. Coggin will join Dr. Schmidt this summer. He will focus on isolating and characterizing mutant Chlamydomonas strains with photosynthetic systems deficient xanthophylls. He will chemically mutagenize the cells and then screen them by their larger chromolography. The cells would then be characterized.