We propose to begin a molecular analysis of the sensory properties of the fungus, Phycomyces blakesleeanus. Several mutations have been identified which block signal transfer at specific steps in the sensory transduction pathway. We plan to design a vector system for manipulating Phycomyces genes and to work out a procedure for introducing such vectors into Phycomyces by transformation or by microinjection. We will attempt to identify the sensory genes from a genomic library by their ability to restore function when introduced into host strains carrying the appropriate mutations in the sensory pathway. We can then hope to begin a detailed molecular analysis of these genes and their products to explore how their interactions lay down the sensory network.