Figure 3. Effects of mtfA deletion on ST production in A. nidulans strains with a veA+ allele.

A) TLC analysis showing ST production in GMM cultures. Wild type (WT) veA+ control (TRV50.2), ΔmtfA (TRVpΔmtfA) and ΔmtfA-com complementation strain (TRVΔmtfA-com) were spread-inoculated with 5 mL of top agar containing 10⁶ conidia mL⁻¹ and incubated at 37°C in the dark or in the light for 48 h and 72 h. ST was extracted and analyzed by TLC as described in the Materials and Methods section. White arrows indicate unknown compounds whose synthesis is also affected by the presence or absence of mtfA. B) Effect of the mftA deletion on aflR and stcU expression. Wild type (WT) veA+ control (TRV50.2), ΔmtfA (TRVpΔmftA) and ΔmtfA-com complementation strain (TRVΔmtfA-com) were inoculated in liquid GMM. Mycelia were collected 24 h and 48 h after inoculation. Cultures were grown in a shaker incubator at 37°C at 250 rpm. Expression of aflR and stcU was analyzed by Northern blot. 18S rRNA serves as loading control. Asterisk indicates not detected. C) TLC showing accumulation of ST in the cultures described in (B). Densitometries were carried out with the Scion Image Beta 4.03 software.