9318708 Snell Dr. Snell proposes to study cell fusion in the biflagellated alga, Chlamydomonas. During the mating reaction of this unicellular organism, gametes of opposite mating types initially adhere to each other via adhesion molecules, agglutinins, on their flagella. Adhesion and fusion of the cell bodies of the two interacting gametes occur at the tips of protuberances termed mating structures, whose activation at the apical ends of the cell bodies is induced by signals generated during the initial flagellar adhesion. The activated mt minus mating structure is a dome-shaped, apical swelling of the plasma membrane, whereas the activated mt plus mating structure is a microvillus-like, actin-filled tubule called the fertilization tubule, that extends several microns from the surface of the mt plus gamete. Dr. Snell will use an integrated approach to identify and characterize the molecules on these fusion organelles that bring about their adhesion and fusion. He will isolate mt plus fertilization tubules and apply biochemical and immunological methods to identify the membrane proteins that are responsible for adhesion/fusion with the tip of the mt minus mating structure. These experiments will be complemented by both biochemical and molecular genetic studies on mutants with non-adhesive fertilization tubules, including new fusion-defective mt plus mutants generated in his laboratory by insertional mutagenesis. Dr. Snell will clone the genes that were tagged by the inserted DNA and will study their role in cell fusion. The distinctive properties of these fusion organelles in Chlamydomonas, along with excit ing new developments in molecular methods for studying this organism, offer a unique possibility for learning more about the molecular and chemical mechanisms underlying fusion of cellular membranes. *** ( 4 ( 9318708 Snell Dr. Snell proposes to study cell fusion in the biflagellated alga, Chlamydomonas. During the mating reaction ! ! F << ( Times New Roman Symbol & Arial " h C e# + Dana Brigham Dana Brigham
