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J DeSimone, WA Schroeder, JB Shelton, JR Shelton, Z Espinueva, V Huynh, L Hall and D Zwiers
In the baboon (Papio species), the two nonallelic gamma-genes produce
gamma-chains that differ at a minimum at residue 75, where isoleucine (I
gamma-chain) or valine (V gamma) 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 I gamma-chains
are identical with those in the above mentioned types, the V gamma-chains
have the substitutions ala----gly at residue 9 and ala----val at residue
23. The V gamma-chains of P. cynocephalus are called V gamma C to
distinguish them from the V gamma A-chains of P. anubis, etc. A single
cynocephalus animal has been found to have only normal I gamma-chains and I
gamma C-chains (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 production than do P. cynocephalus, and
hybrids fall between. Minimal data on P. hamadryas and P. papio suggest an
even lower response than P. cynocephalus. As HbF increases under stress,
the ratio of I gamma to V gamma-chains changes from the value in the adult
or juvenile baboon toward the ratio in the newborn baboon. However, it does
not attain the newborn value. The V gamma A and V gamma C-genes respond
differently to stress. In hybrids, the production of V gamma A- chains
exceeds that of V gamma C-chains. A controlling factor in cis apparently is
present and may be responsible for the species-related extent of total HbF
production. It may be concluded that the more primitive the cell in the
erythroid maturation series that has been subjected to 5-azacytidine, the
more active is the I gamma-gene.
This article has been cited by other articles:
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| Copyright © 1984 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
