Figure 3

Gene module reorganization in complete clusters and modularity in partial clusters. The cluster schematic shows the chromosomal location, gene order and direction of transcription of genes in ST, AF and partial gene clusters. To simplify comparisons among AF and ST clusters we adopt the new AF gene nomenclature throughout [17]. The seven inferred gene modules are color coded. The arrows in the cluster at the top indicate the location of noncontiguous recombination blocks in the A. parasiticus gene cluster [40]. The intergenic regions indicated by the black arrows share a common evolutionary history and can be concatenated into a single contiguous block such that aflB and aflL are adjacent in a hypothetical ancestor. Similarly the intergenic regions shown with grey arrows can be reunited such that aflE and aflW are adjacent. Overall this reorganization mirrors the order of these genes in the A. nidulans ST cluster and highlights the importance of gene module reorganization in the evolution of AF and ST clusters. A partial cluster duplication has been reported for some strains of A. parasiticus [71]. Syntenic partial clusters of five genes (aflC, aflS, aflR, aflX and aflY) were identified in A. fumigatus and A. terreus.