Figure 1

Complete structure of DIRS1 -like retrotransposons indicating the position of degenerate primers along the pol region. A. Structure of the DIRS1 element identified in the slime mold Dictyostelium discoideum. The inverted terminal repeats (ITR) and the Internal Complementary Region (ICR) are represented by black triangles and hatched box, respectively. The three ORFs, encoding the GAG, the tyrosine recombinase (YR) and the pol regions (Reverse transcriptase (RT)/RnaseH (RH)/MethylTransferase (MT) domain series) correspond to shaded boxes. B. Positions of the degenerated primers defined in this study along the DIRS1-like pol region. Three types of primers are represented: in grey bold, the GD primers that correspond to conserved motifs of Ty3/gypsy-like retrotransposons, also shared with DIRS1-like elements; in black bold, the DD primers that correspond to conserved motifs specific to DIRS1-like elements and underlined, the non degenerate primer Retro1+ that spans the highly well-conserved YLDD motif that is present in both LTR retrotransposons and DIRS-like elements. For each primer, the orientation (arrow) and the corresponding conserved motif (uppercase) are indicated.