Figure 1.

Duplication of the matA gene in the haploid genome of A. nidulans prevents ascospore formation. Differentiation of cleistothecia and ascospores are compared in the wild type (WT) and a transformant with a matA duplication (T). (Top panels) Mature, dark-pigmented cleistothecia and mature white conidiophores. (Middle panels) (Left) Contents of the individual broken cleistothecium with mature ascospores (arrow). (Right) Undeveloped ascogenous tissue with orange debris (arrow). (Bottom panels) (Left) Mature ascospores (arrow) produced by wild-type strain. (Right) Debris (arrow) with absence of ascospores. Magnification bars are shown.