Discovery of alpha-defensins in basal mammals.
Alpha-defensins are essential molecules of the innate immune system that have broad spectrum antimicrobial activity against a range of bacteria and viruses. To date, alpha-defensins have only been identified in the Euarchontoglires branch of the mammals. This has led to speculation that alpha-defensins may be specific to this group, a somewhat surprising finding, given their importance in the immune system. The mammalian genome project provided us with the opportunity to search for alpha-defensins in previously unexamined mammalian superorders. Using hidden Markov model (HMM) profile searching, we report the discovery of alpha-defensins in the African savanna elephant, the lesser hedgehog tenrec, and the nine-banded armadillo genomes representing two of the most basal mammalian superorders, Afrotheria and Xenarthra. Furthermore, we identify an alpha-defensin-like gene in the gray short-tailed opossum, suggesting that alpha-defensins may have evolved much earlier than previously thought, before the divergence of placental mammals and marsupials approximately 130 mya.
Lynn
David J
DJ
Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland. david.lynn@tcd.ie
Bradley
Daniel G
DG
D000595:Amino Acid Sequence; D000818:Animals; D019143:Evolution, Molecular; D008322:Mammals / Q000378:metabolism*; D008969:Molecular Sequence Data; D023084:alpha-Defensins / Q000737:chemistry* / Q000378:metabolism*
D023084:alpha-Defensins