Primate evolution of the α-globin gene cluster and its Alu-like repeats

Abstract

The arrangement of α-globin genes in Old World and New World monkeys and a prosimian, galago, has been determined by restriction mapping. Recombinant DNAs containing galago and Old World monkey α-globin genes have been isolated and subjected to a partial sequence determination for comparison to α-globin genes in human, chimpanzee and non-primate mammals. The results of this extensive structural analysis are relevant to several topics concerning the evolution of primate α-globin genes and Alu family repeats. All orders of higher primates (i.e. Old and New World monkeys, chimpanzee and human) have the same arrangement of α-globin genes. In contrast, the arrangement and correction of galago α-globin genes differ from those of higher primates, but are similar to those of non-primate mammals. The 5- and 3-flanking regions of the human α1 gene are orthologous to the corresponding region in galago, identifying the human α2 gene as the more recently duplicated gene. The human ψα1 gene is found to be inactivated after divergence of the human and galago lineages but prior to the divergence of human and monkey. Orthologous Alu family members in human and monkey DNAs indicate that the dispersion of some Alu repeats occurred prior to the divergence of these lineages. However, the Alu-like repeats of prosimian and higher primates result from entirely independent events giving rise to different repeat elements inserted at distinct genomic positions.