Speciation in the Baboon and its Relation to "y-Chain Heterogeneity and to the Response to Induction of HbF by 5-Azacytidine

In the baboon (Papio species), the two nonallelic 'y-genes produce "y-chains that differ at a minimum at residue 75. where isoleucine ("y-chain) or valine (�y) may be present. This situation obtains in baboons that are sometimes designated as Papio anubis, Papio hamadryas, and Papio papio. However, in Papio cynocephalus. although the "y- chains are identical with those in the above mentioned types. the vchains have the substitutions ala -' gly at residue 9 and ala -' val at residue 23. The"y-chains of P. cynocephalus are called VyC to distinguish them from the v��,Achains of P. anubis. etc. A single cynocephalus animal has been found to have only normal 7-chains and LyCchains (that is, glycine in residue 9. valine in 23, and isoleucine in 75). When HbF is produced in response to stress with 5-azacytidine. P. anubis baboons respond with greater