N&N: Immunity before the backbone
“New and Noted” in PLoS ONE
The Identification of Lymphocyte-Like Cells and Lymphoid-Related Genes in Amphioxus Indicates the Twilight for the Emergency of Adaptive Immune System.
Huang G, Xie X, Han Y, Fan L, Chen J, et al. (2007) PLoS ONE 2(2): e206. doi:10.1371/journal.pone.0000206
The amphioxus comes from an ancient evolutionary lineage that diverged from that of mammals some 600 million years ago. Nevertheless, this paper reveals cells and genes in amphioxus that react to microbial pathogens as white blood cells do. This suggests that the adaptive immune system may have appeared even before animals had backbones.