FIG. 3.
(A) Phenotype effect of signaling mutants. Strains shown are wild-type A. nidulans (a), ΔfluG (b), ΔflbA (c), fadAG42R (d), and ΔpkaA (e). (B) Proposed model of G-protein signal transduction regulating sterigmatocystin production and sporulation. Arrows indicate positive regulation, and blocked arrows indicate negative regulation. Solid lines indicate known pathways. Dashed lines indicate postulated pathways. Abbreviations: FluG, early acting developmental regulator; FlbA, regulator of G-protein signaling; FadA, α subunit of G-protein; PkaA, catalytic subunit of PKA; LaeA, AflR regulator; AflR, sterigmatocystin-aflatoxin-specific transcription factor; BrlA, conidiation-specific transcription factor (55, 106).