We aim to investigate iron homeostasis in the model organism C. reinhardtii. Ferritin, a 24-multimeric complex involved in iron storage and located in the chloroplast, is a key component to regulate iron intracellular concentration. We first will construct strains that over or under express ferritin. For this we will take advantage of the existence of a ferritin cDNA, that will be inserted in both orientations under the control of an HSP70 promoter. Nuclear transformation will allow the insertion of the constructs into the genome of a recipient strain. We will compare the phenotype of the resulting strains with wild-type strains grown under different iron concentrations I mainly at two levels. The expression of certain genes that are known to respond to iron concentration will be investigated by Northern Blot. The chloroplast protein content will be monitored by two-dimensional gel electrophoresis, and proteins that display a differential expression will be analyzed by mass spectrometry. Protein network involved in chloroplast iron homeostasis or ferritin regulation will then be identified. Our goal is to dissect ferritin function in chloroplast relevant and in general aspects of iron homeostasis. The proposed research project will allow me to develop new competencies on the Biochemistry of the model organism C. reinhardtii (chloroplast proteome analysis by 2D electrophoresis and mass spectrometry, protein complex purification using FPLC). I will also learn nuclear transformations which complete my experience in chloroplast transformation. I think that having a broad and integrated knowledge on many aspects of C. reinhardtii Biology will be a great advantage in my carrier. The host group will take benefit of my strong background in Molecular Biology and my knowledge in Genetics.