Contrasting evolution of diversity at two disease-associated chicken genes
- 300 Downloads
There have been significant evolutionary pressures on the chicken during both its speciation and its subsequent domestication by man. Infectious diseases are expected to have exerted strong selective pressures during these processes. Consequently, it is likely that genes associated with disease susceptibility or resistance have been subject to some form of selection. Two genes involved in the immune response (interferon-γ and interleukin 1-β) were selected for sequencing in diverse chicken populations from Pakistan, Sri Lanka, Bangladesh, Kenya, Senegal, Burkina Faso and Botswana, as well as six outgroup samples (grey, green, red and Ceylon jungle fowl and grey francolin and bamboo partridge). Haplotype frequencies, tests of neutrality, summary statistics, coalescent simulations and phylogenetic analysis by maximum likelihood were used to determine the population genetic characteristics of the genes. Networks indicate that these chicken genes are most closely related to the red jungle fowl. Interferon-γ had lower diversity and considerable coding sequence conservation, which is consistent with its function as a key inflammatory cytokine of the immune response. In contrast, the pleiotropic cytokine interleukin 1-β had higher diversity and showed signals of balancing selection moderated by recombination, yielding high numbers of diverse alleles, possibly reflecting broader functionality and potential roles in more diseases in different environments.
KeywordsChicken Interleukin 1 beta Interferon gamma Selection Population genetics
This work is supported by Government of Ireland Department of Agriculture FIRM grant 04/R + D/D/295. We would like to thank the Department of Ornithology and Mammalogy, Californian Academy of Sciences (San Francisco, USA) and Donal Campion, Wallslough Farm (Co. Kilkenny, Ireland) for bird samples and Karsten Hokamp (Trinity College, University of Dublin) for help in implementing LDhat.
- De Nardo D, Masendycz P, Ho S, Cross M, Fleetwood AJ, Reynolds EC, Hamilton JA, Scholz GM (2005) A central role for the Hsp90.Cdc37 molecular chaperone module in interleukin-1 receptor-associated-kinase-dependent signaling by Toll-like receptors. J Biol Chem 280(11):9813–9822PubMedCrossRefGoogle Scholar
- Kogut MH, He H, Kaiser P (2005b) Lipopolysaccharide binding protein/CD14/ TLR4-dependent recognition of salmonella LPS induces the functional activation of chicken heterophils and up-regulation of pro-inflammatory cytokine and chemokine gene expression in these cells. Anim Biotechnol 16(2):165–181PubMedCrossRefGoogle Scholar
- Kogut MH, Swaggerty C, He H, Pevzner I, Kaiser P (2006) Toll-like receptor agonists stimulate differential functional activation and cytokine and chemokine gene expression in heterophils isolated from chickens with differential innate responses. Microbes Infect 8(7):1866–1874PubMedCrossRefGoogle Scholar
- Long JE, Huang LN, Qin ZQ, Wang WY, Qu D (2004) IFN-gamma increases efficiency of DNA vaccine in protecting ducks against infection. World J Gastroenterol 11(32):4967–4973Google Scholar
- Okamura M, Lillehoj HS, Raybourne RB, Babu US, Heckert RA (2004) Cell-mediated immune responses to a killed Salmonella enteritidis vaccine: lymphocyte proliferation, T-cell changes and interleukin-6 (IL-6), IL-1, IL-2, and IFN-gamma production. Comp Immunol Microbiol Infect Dis 27(4):255–272PubMedCrossRefGoogle Scholar
- Quesada H, Ramirez UE, Rozas J, Aguade M (2006) Large-scale adaptive hitchhiking upon high recombination in Drosophila simulans. Genetics 165(2):895–900Google Scholar
- Schneider S, Roessli D, Excoffier L (2000) Arlequin: a software for population genetics data analysis, ver 2.000. Genetics and Biometry Lab, Department of Anthropology, University of GenevaGoogle Scholar