Abstract
The presence of the Ll sequences, L1Md4 next to the pseudogene βh3 and 112 found in the twelfth intron of the albumin gene, in certain strains of laboratory mice but not of others has led to the suggestion that these sequences were recent insertions into the Mus mus domesticus genome. To be sure that they are really recent insertions and not relics of an ancestral chromosome, we investigated the presence or absence of these sequences in populations of wild mice belonging to the semispecies M. m. domesticus and M. m. muscuIus as well as in other species of the genus Mus and in related murids. The sequence 112 in the albumin gene was found in 34% of the chromosomes of the wild mice belonging to M. m. do- mesticus and to a lesser extent (6%) in M. m. musculus. Of 114 M. m. domesticus chromosomes, L1Md4 was found in only nine, seven of which came from the same locality. Its presence was associated with the haplotype HbbP, which is relatively rare in European populations of M. musculus. Since there was no evidence for the presence of these two Ll sequences in more distantly related species, we conclude that they are recent insertions in the M. musculus genome.