Transposon associated markers for the parasitic nematode Haemonchus contortus

We have previously characterized a Tc1-like transposable element Hctc1. fro m the parasitic nematode Haemonchus contortus. Here we describe the genetic variation of Hctc1 insertion sites in H. contortus populations differing i n geographical origin, resistance to chemotherapeutics and level of inbreed ing, Clear differences between populations were observed on Southern blots with a Hctc1-specific probe. Sequencing the 5'- or 3'-flanks of individual Hctc1 integration sites allowed the design of PCR reactions between a Hctc1 -specific primer and the flanking regions. This revealed a considerable var iation of integration sites of Hctc1 both within and between populations. a lthough several integrations were shared by populations of different geogra phical origin. For four of the eight markers allele frequencies were shifte d during selection for resistance to chemotherapeutics and/or inbreeding. F or two positions both the 5' and 3' regions flanking Hctc1 were isolated an d PCR showed that For these two positions the variation of transposon assoc iated markers between populations were indeed caused by variation in integr ation of Hctc1. For these two positions co-dominant markers were developed. These results indicate that Hctc1 insertions may serve as genetic markers for H. contortus. (C) 2000 Elsevier Science B.V. All rights reserved.