HeT-A regions amplified in this study. Middle, schematic drawing of the HeT-A complete element. Upper and lower, nucleotide alignment of the amplified fragments from the gag gene and the 3'UTR using all previously sequences of the HeT-A elements from Drosophila melanogaster containing this region available in the data base. Sequences corresponding to the fragment inside the gag gene (from upper to lower): 01D09, 4R6265, 4R6274, XL4800, 17B3, 4R6262, 4R6268, 23Zn-1, 4R6276 and 9D4. Sequences from the fragment inside the 3'UTR region (from upper to lower): 1187X, 3Zn-1, RT394, 44PChrIII, 4R6276, 23Zn-3, RT473, 4R6270, 4R6278, 4R6269, XL4800, AJ549609, XL6255, XL5504, CS-T-A1, CS-T-A2, HTChrIII, XL4795, 4R6262, XL6256, 4R6268, 4R6277, 4R6265 and 4R6274. For correspondence of sequence name with the accession numbers see Additional file 2.