1 °C s−1 to 95 °C. Fluorescence was monitored at regular intervals during the extension step and continuously during the melting. The experiment was

completed in approximately 45 min. The target sequence is detected when the fluorescence curve MK-1775 concentration turns abruptly upward above the threshold. Each DNA sample is characterized by this point of the curve, called the crossing point (Cp). The specificity of the primers tested on type strains was then validated using DNA extracted from a set of 11 Aspergillus section Flavi strains, two other Aspergillus species and six fungal genera commonly found in the environment (Table 1). Within the section Flavi, PCR results were compared with the identification data obtained by means of the calmodulin gene sequencing as described previously (O’Donnell et al., 2000). Three RAPD analyses were performed as described by Yuan et al. (1995) with the primers OPA-04, OPB-10, OPR-01, and sequences AATCGGGCTG, CTGCTGGGAC and TGCGGGTCCT, respectively. DNA amplification was carried out in a final volume of 25 μL containing 100 ng of template DNA, 5 pmol of primer (Sigma-Aldrich), 1 U of Taq DNA polymerase (Sigma-Aldrich), Daporinad cost 1 × of Taq DNA buffer (Sigma-Aldrich), 100 μM of dNTPs and 1.5 mM MgCl2. Amplification was performed

in a thermocycler (Biometra, Tgradient, Göttingen, Germany) and the amplified products were separated by gel electrophoresis according to Yuan et al. (1995), except that the gel was stained with GelRed™ (Biotium Inc., Hayward, CA). One microgram of DNA was digested with SmaI (Klich & Mullaney, 1987) under the following conditions: overnight incubation at 25 °C in a final

volume of 25 μL containing 1 U of SmaI (Roche Diagnostics GmbH) and 1 × of buffer. Restriction was fractionated by electrophoresis on a 0.7% agarose gel stained with GelRed™ (Biotium Inc.). Two primers, Afaflt-F (forward) and Afaflt-R (reverse), were designed Silibinin on a region of the aflT gene presenting a low level of homology between A. flavus, A. oryzae and other four species of the section Flavi for which the gene sequences were available in GenBank (Fig. 1a). A second primer set, Anits-F (forward) and Anits-R (reverse), was designed on a region of the A. nomius ITS1–ITS2 region unique to this species (Fig. 1b). Before PCR amplification, the theoretical specificity stringency of the primers designed for species of the Aspergillus section Flavi was evaluated using the basic local alignment search tool (blast, NCBI). For each set, no fungal species other than the target Aspergillus species were proposed, i.e. A. oryzae and A. flavus for Afaflt-F/Afaflt-R and A. nomius for Anits-F/Anits-R. Different times and annealing temperatures were tested to define the optimal conditions required for each primer set specificity.