The wild type and silenced isolate were grown for eight days in Tinline medium , which contains 83 mM AZD1480 glucose and 2 mM asparagine as carbon selleck products and nitrogen sources. Since starvation for at least one amino acid is sufficient to induce cpcA expression in A. fumigatus , amino acid starvation was induced in cultures of L. maculans wild type and cpcA-sil isolates by addition of the ‘false
feedback’ inhibitor, 3-aminotriazole (3AT), a histidine analog that inhibits the histidine biosynthetic enzyme, imidazole glycerol phosphate dehydratase . Five hours later, levels of transcripts of several genes relative to actin were measured by q RT-PCR. In the absence of 3AT, transcript levels of cpcA in the silenced isolate, cpcA-sil, were 7% of that of wild type. In the presence
of 5 mM 3AT, transcript levels of cpcA increased significantly in the wild type (3 fold; p = 0.004) and in the silenced isolate (6 fold; p = 0.009) and yet the transcript levels of cpcA in the silenced isolate remained only 16% of that of wild type (Figure 3A). Next the ability of learn more L. maculans CpcA to regulate amino acid biosynthesis was examined. In Aspergillus spp., transcript levels of tryptophan synthase, trpC, increase upon amino acid starvation, but remain low in isolates that are mutated in cpcA, whereas transcript levels of chorismate synthase, aroC, remain unchanged [14, 18]. After 8 days in Tinline media, there was no significant difference in transcript levels of trpC of wild type or silenced isolates of L. maculans (data not shown). As expected, transcript levels of trpC increased significantly in wild type L. maculans
in the presence of 5 mM 3AT (4 fold; p = 0.0003); a smaller increase was seen in the cpcA-silenced isolate (2 fold; p = 0.01). No significant differences in transcript levels of aroC were observed, even during amino acid starvation (Figure 3A). The levels of transcripts Montelukast Sodium of sirZ and sirP, which are involved in sirodesmin PL biosynthesis did not differ significantly (p = 0.9 and 0.5) in the wild type in the presence or absence of 5 mM 3AT. However, there was a significant increase in transcript levels of sirZ (p = 0.008) and sirP (p = 0.0005) in the cpcA-silenced isolate after 5 h of amino acid starvation (Figure 3B). Figure 3 Quantitative Reverse Transcription PCR analysis of (A) cpcA, trpC and aroC , (B) sirZ and sirP in wild type (wt) and a cpcA -silenced (cpcA-sil) isolate of Leptosphaeria maculans. Six replicates of each isolate were grown in Tinline for eight days and then mycelia were washed and then transferred to fresh Tinline media for 5 h with 5 mM 3AT (+) or without 3AT (-). RNA was isolated from all treatments, cDNA prepared and q RT-PCR carried out. Transcript level is normalised to that of actin. Values are means ± SE of triplicate reactions of three independent biological samples. Asterisks mark values that have a significant increase (p < 0.