GYPSY TY3-LIKE ELEMENTS IN THE GENOME OF THE TERRESTRIAL SALAMANDER HYDROMANTES (AMPHIBIA, URODELA)/

We have studied a family of long repetitive DNA sequences (Hsr1) inter spersed in the large genome of the European plethodontid salamander Hy dromantes. The sequence analysis of a 5-kb fragment (Hsr1A) of one mem ber has revealed significant similarities with aminoacidic domains of retroviruses and retrotransposons. The similarity of the reverse trans criptase domain and the gene organization identifies Hsr1A as a member of the gypsy/Ty3 class of retrotransposons. We hypothesize that Hsr1 sequences are vestiges of an invasion of the Hydromantes genome that o ccurred early in the evolutionary history of these European plethodont ids. About 10(6) Hsr1 sequences are present in the large Hydromantes g enome. This is the highest number of copies so far discovered for retr otransposon-like elements in eukaryote organisms.