Characterization of Tc1 transposon-like sequences in notothenioids

The Tc1 family of transposable elements is composed of DNA-mediated transpo sons with inverted terminal repeats and an open reading frame encoding a pu tative transposase. These elements have been identified in a wide range of organisms, among which several fish species. Here we report on the presence of a Tc1-like element in the ice-fish Chionodraco hamatus. This clement, o nly 800 bp long, is shorter than those observed so far and contains a degen erate open reading frame of approximately 440 bp bearing several deletions, Corresponding sequences were found in thc genomes of other notothenioid sp ecies after Southern-blot hybridization and polymerase chain reaction ampli fication. Although the efficiency of this widespread Tc1 element as a phylo genetic marker is still debated, it can br hypothesized that the Tc1-like f amily isolated in C, hamatus appeared early in the genome of notothenioids, and its divergence probably accompanied or occurred in parallel to thr evo lutionary history of this taxon.