Comparative study of the L1 family in the genus Mus. Possible role of retroposition and conversion events in its concerted evolution.

The long interspersed repetitive family L1 was analysed in different species belonging to the genus Mus. It is shown to be highly conserved even in M.n. setulosus, which diverged from the other species around ten million years ago. The study of the linkage between diagnostic restriction sites in the various species and the sequence variations of different regions of the L1Md repeat shows that the L1 family undergoes concerted changes involving subsets of repeats. The rate at which this homogenization process occurs does not appear to be the same for all the subfamilies detected. The L1Md repeat in the twelfth intron of the serum albumin gene of Balb/c mice is shown to be a recent insertion. The role retroposon- and gene conversion-like events may play in the concerted evolution of the L1 family is discussed.