Embryonic ε and γ globin genes of a prosimian primate (Galago crassicaudatus). Nucleotide and amino acid sequences, developmental regulation and phylogenetic footprints

Sequence analysis of ε and γ genes and encoded globins and high-pressure liquid chromatography analysis of globin compositions in blood hemolysates obtained from embryos, fetuses and adults show that the prosimian primate Galago crassicaudatus expresses its ε and γ genes only embryonically. Since rabbit, mouse and galago all have embryonic γ genes but simian primates have fetal γ genes, we conclude that γ_E evolved into γ_F in stem-simians. An elevated non-synonymous substitution rate characterizes this transition. The alignment of ε and γ nucleotide sequences and the parsimoniously reconstructed evolutionary history of these sequences identify several anciently conserved cis-regulatory elements (phylogenetic footprints) important for γ expression in primates and also cis-mutations which may have been involved in the recruitment of the γ gene to a fetal program in simian primates.