Project Summary Many invasive fungal diseases start when spores inhaled from the environment break dormancy and begin active growth within the host. Despite their critical importance to the fungal life cycle and potential as antifungal targets, the establishment and maintenance of spore dormancy are poorly understood. The proposed pilot study in the human pathogen Aspergillus fumigatus focuses on fungal- specific genes of unknown function that have high transcript levels in dormant asexual spores (conidia) and low levels in actively growing cells. Genes with this particular expression pattern, designated hic (high in conidia) genes, are likely to be involved in the establishment or maintenance of spore dormancy. In the proposed pilot study, the 25 hic genes with the most differential transcript levels in dormant vs nondormant cells will be characterized through deletion and tagging. Deletion strains will be analyzed for changes in development, dormancy, and germination using flow cytometry and microscopy. Tagged strains will be analyzed for localization of Hic proteins during development, dormancy, and germination using fluorescence microscopy. Tagged strains will also be used in affinity purification and mass spectroscopy to identify interacting proteins. Successful completion of the proposed pilot study will identify a set of genes important for establishing and maintaining dormancy in fungal conidia along with localization and interaction data for the transition to dormancy during development and from dormancy to active growth.