Cytoskeleton interactions in the ascus development and sporulation of Sordaria macrospora

Abstract

The organization of actin during meiosis and sporulation in the ascus of the filamentous ascomycete Sordaria macrospora was determined by immunofluorescence without removal of the cell wall. Actin is present as a dense cortical network of microfilaments (MF) and plaques, a perinuclear shell of actin in prophase I of meiosis, and a complex array of MF involved in alignment of prespore nuclei and closure of spore cell membranes. The relationship of actin to the previously examined microtubule system of the ascus was determined by double-label immunofluorescence. The cytoskeletal inhibitors nocodazole, cytochalasin D and 2,3-butanedione monoxime were used to examine the roles of actin and myosin in ascus development. Microfilament and microtubule arrays are interdependant; disruption of one network results in abnormalities in the other. Both microfilaments and actin-myosin interaction are required for separation and migration of duplicated spindle pole bodies, septation and sporulation