Characterisation of a polymorphic Tc1-like transposable element of the parasitic nematode Haemonchus contortus

Hctc1, a member of the Tc1-family of transposable elements was isolated fro m the parasitic nematode Haemonchus contortus. Hctc1 is 1590 bp long, is fl anked by 55 bp inverted repeats and carries a single open reading frame of a 340 amino acid transposase-like protein. Hctc1 is similar to Tc1 of Caeno rhabditis elegans and elements Tcb1 and Tcb2 of Caenorhabditis briggsae in the inverted terminal repeats, the open reading frame, as well as the targe t insertion sequence. Furthermore, the copy number of Hctc1 is comparable w ith the Tc1 copy number in low copy strains of C. elegans. The sequence of Hctc1 is highly variable in H. contortus due to deletions, insertions and p oint mutations, with at least five distinct length variants of Hctc1. Most of the Hctc1 variation was within rather than between H. contortus populati ons. The high level of sequence variation is probably due to variation gene rally found for members of the Tc1-family, as well as a high background lev el of genetic variation of H. contortus. (C) 1999 Elsevier Science B.V. All rights reserved.