Solbakken Monica H, Rise Matthew L, Jakobsen Kjetill S, Jentoft Sissel
Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada.
Genome Biol Evol. 2016 Dec 31;8(11):3508-3515. doi: 10.1093/gbe/evw250.
Great genetic variability among teleost immunomes, with gene losses and expansions of central adaptive and innate components, has been discovered through genome sequencing over the last few years. Here, we demonstrate that the innate Myxovirus resistance gene (Mx) is lost from the ancestor of Gadiformes and the closely related Stylephorus chordatus, thus predating the loss of Major Histocompatibility Complex class II (MHCII) in Gadiformes. Although the functional implication of Mx loss is still unknown, we demonstrate that this loss is one of several ancient events appearing in successive order throughout the evolution of teleost immunity. In particular, we find that the loss of Toll-like receptor 5 predates the loss of Mx involving the entire Paracanthopterygii lineage. Using a time-calibrated phylogeny, we show that loss of MHCII and Mx overlap with major paleoclimatic and geological events indicating that these genetic changes were adaptive responses to the changing environment at the time.
在过去几年中，通过基因组测序发现，硬骨鱼免疫组之间存在巨大的遗传变异性，同时中央适应性和先天性成分的基因出现丢失和扩增。在此，我们证明，在鳕形目及其近缘的线口鳗的祖先中，先天性抗黏液病毒基因（Mx）已经丢失，因此这一事件早于鳕形目中主要组织相容性复合体II类（MHCII）的丢失。虽然Mx基因丢失的功能影响仍然未知，但我们证明，这种丢失是硬骨鱼免疫进化过程中依次出现的几个古老事件之一。特别是，我们发现Toll样受体5的丢失早于整个副棘鳍总目谱系中Mx基因的丢失。通过时间校准的系统发育分析，我们表明，MHCII和Mx基因的丢失与主要的古气候和地质事件重叠，这表明这些基因变化是当时对不断变化的环境的适应性反应。
