Repetitive DNA sequence homologies and amplifications in South American cricetid rodents

The extent of conservation of repetitive DNA sequences in five species of South American cricetid rodents, belonging to three tribes and genera, exhibiting clear karyological differences has been investigated. Dot blot evaluation of interspecific hybridization percentages underscored sharp discrepancies in some reciprocal assays, suggesting sequence amplification events might have taken place since the evolutionary divergence of the species studied. Southern blot analysis, employing the most intense restriction bands of three species' DNAs as radiolabeled probes, allowed to confirm the sequence amplification events initially suspected. Although homologous repetitive sequences are conserved in the genomes of the species investigated, differential organization of such sequences does exist, as judged by the species-specific Southern blot patterns.