Fast evolution of interleukin-2 in mammals and positive selection in ruminants.
J Mol Evol
; 51(3): 234-44, 2000 Sep.
Article
em En
| MEDLINE
| ID: mdl-11029068
ABSTRACT
Interleukin-2 (IL-2) is a cytokine involved in induction and regulation of the immune response in mammals. There have been numerous reports about the search for IL-2 in species other than mammals, and recently an IL-2-like gene has been isolated in chicken. Using PCR, we searched for IL-2 gene sequences in a wide variety of mammals, including marsupials and monotremes, as well as in birds. Although we can readily amplify IL-2 gene fragments in placental mammals, no amplification was obtained in other species. This is best explained by very high substitution rates. This suggest that strategies to isolate IL-2 homologous genes outside mammals should involve functional assays, as for the chicken gene, and not hybridization-based techniques. Nonsynonymous substitution rates are especially high in ruminants, due to positive selection acting on regions important in term of structure-function. We suggest that, although globally similar, the immune response of various mammals is not identical, mainly at the level of cytokine-mediated regulations.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Seleção Genética
/
Ruminantes
/
Interleucina-2
/
Evolução Molecular
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Mol Evol
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
França