The molecular organization of the beta-globin complex of the deer mouse, Peromyscus maniculatus

Recombinant DNA clones have been isolated that contain 80 kb of thebeta-globin complex from the deer mouse, Peromyscus maniculatus.Comparisons of this complex with that from the laboratory mouse, Musdomesticus (with an order 5'-Hbby, Hbb-bhO, Hbb-bhl, Hbb-bh2, Hbb-bh3,Hbb-bl, Hbb-b2 3') highlight organizational trends in the beta-globincomplex since the two species diverged. Unlike other mammals studied thusfar, the deer mouse possesses three adult genes. Partial sequence analysisindicates that each of the three adult genes is intact and hence may befunctional. Hybridization of one of the two Mus pseudogenes, Hbb-bh3, togenomic blots from Peromyscus reveals that it has a homologous counterpartin Peromyscus. Homologous genes to the two gamma-like Mus genes, Hbb-bhOand Hbb-bhl, are also found in Peromyscus. The strong hybridization betweenthe Hbb-bhl genes and significant nucleotide similarity between the Hbb-bhOgenes suggest that both pairs are important for the ontogeny of these micealthough no known product has been identified for the Hbb-bhO genes. Thepresence of Hbb-bhO and Hbb-bhl in Peromyscus suggests that the duplicationthat created this related gene set occurred before the two lineagesdiverged. A single gene for Hbb-y has been isolated from Peromyscus. Theadult region in Peromyscus has undergone significant divergence from thesame region in Mus, having three rather than two adult genes, theacquisition of at least 15 kb of extra DNA relative to Mus, and possiblythe loss of the Hbb-bh2 pseudogene. The nonadult region of the complex, incontrast, contains the same set of genes apparently distributed over thesame amount of DNA as in the Mus beta- globin complex. This observationsuggests that the embryonic region of the complex is more evolutionarilystable than the adult region.