Figure 1. N. crassa SIN components are required for septum formation but display distinct mutant characteristics.

(A) Deletion strains defective in the indicated SIN components generate thin and aseptate hypha in young colonies (18 h time point). In older colonies, the septation defects were suppressed in ∆sid-1 and ∆cdc-14 strains (36 h time point). Cell wall and septa were labeled with Calcofluor White. (B) SIN mutants showed cytoplasmic leakage (magnified inserts), but, due to the fast ability to septate, ∆sid-1 and ∆cdc-14 generated abundant aerial mycelium and asexual spores (conidia; plate morphology). (C) SIN mutants displayed distinct abnormalities during sexual development. wt x ∆ crosses with ∆cdc-7(het) and ∆dbf-2(het) resulted in the frequent formation of large, banana-shaped ascospores. In contrast, wt x ∆sid-1(het) progeny morphology was normal, while crosses of wt x ∆cdc-14(het) produced no mature perithecia .