The expression of epsilon- and gamma-globin mRNA and protein has been determined 
in three Old World monkey species (Macaca mulatta, Macaca nemestrina, and 
Cercopithecus aethiops). Using RT-PCR with primers for epsilon- and 
gamma-globin, both mRNAs were detected in early fetal stages, whereas at 128 
days (85% of full term), only gamma was expressed. High-performance liquid 
chromatography was used for separation and quantitation, and matrix-assisted 
laser desorption/ionization mass spectrometry was used for identification of 
globin polypeptides. An alpha-globin polymorphism was observed in all of the 
species examined. During fetal life, gamma-globin was the predominant expressed 
beta-type globin. The red blood cells of infants still contained substantial 
amounts of gamma-globin, which declined to negligible levels in 14 weeks as 
beta-globin expression reached adult values. The ratio of gamma1- to 
gamma2-globins (equivalent to Ggamma/Agamma in humans) was approximately 2.5, 
similar to the Ggamma/Agamma ratio observed in humans. Thus, gamma-globin gene 
expression in these Old World monkeys species has three features in common with 
human expression: expression of both duplicated gamma genes, the relative 
preponderance of gamma1 over gamma2 expression, and the delay of the switch from 
gamma- to beta-globin until the perinatal period. Thus, the catarrhines seem to 
share a common pattern of developmental switching in the beta-globin gene 
cluster, which is distinct from the timing of expression in either prosimians or 
the New World monkeys. Our results indicate that an Old World monkey, such as 
Rhesus, could serve as a model organism (resembling humans) for experimentally 
investigating globin gene expression patterns during the embryonic, fetal, and 
postnatal stages.