Schematic representation of the ALS7 gene. The schematic is based on the gene in strain SC5314. Shapes are used to show the arrangement of the following repetitive elements: the 108-bp element (hollow boxes); the 87-bp element (gray ovals); the 138-bp element (gray boxes); VA/TSES repeats (black boxes; the thickness of the box varies according to the number of tandemly arranged 15-bp units present); and the 141-bp element (hollow circles). At the top of the figure, brackets show the borders of the different domains and regions within the gene, as defined by Hoyer (2001). Labeled thin arrows represent the primers used, with gray arrows indicating primers used for RT–PCR. The hollow arrow indicates a reverse ORF. Numbers at the bottom indicate the position within the gene (in base pairs). Note that the GPG-specific AFLP fragment corresponds to the region from bp 3719 to bp 4957 in the SC5314 gene; however, a point mutation in bp 3723 in SC5314 prevents amplification in the AFLP reaction. Note also that the VASES region of SC5314 is 290 bp longer than that amplified by AFLP for most cluster strains; thus SC5314 DNA did not generate the GPG cluster-specific AFLP product.
