This collaborative project integrates key aspects of cytology, physiology, and biochemistry to resolve a major problem in developmental biology: explaining the most fundamental growth process in fungi -- apical growth of hyphae. Hyphae elongate by a complex mechanism involving movement of wall-building vesicles to the apex. In higher fungi, vesicles assemble in the hyphal tip to form a unique complex called the Spitzenkorper. The Spitzenkorper is suspected of playing a central role in apical growth, but its exact function and mechanisms controlling its action remain unknown. By correlation video-enhanced light microscopy of growing cells, electron microscopy, cytochemistry, and immunocytochemistry, the research will characterize Spitzenkorper organization and behavior. Characterization of apical vesicles will allow determination of their biochemical roles in cell growth. Developmental mutants will be used to correlate Spitzenkorper behavior with hyphal growth and provide clues concerning the control of polarity and apical growth. //