Shih Juliann, Hodge Russ, Andrade-Navarro Miguel A
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA ; Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA, USA.
Max Delbrück Center for Molecular Medicine, Germany.
Genom Data. 2014 Nov 22;3:49-54. doi: 10.1016/j.gdata.2014.11.010. eCollection 2015 Mar.
Variation is essential to species survival and adaptation during evolution. This variation is conferred by the imperfection of biochemical processes, such as mutations and alterations in DNA sequences, and can also be seen within genomes through processes such as the generation of antibodies. Recent sequencing projects have produced multiple versions of the genomes of humans and fruit flies (Drosophila melanogaster). These give us a chance to study how individual gene sequences vary within and between species. Here we arranged human and fly genes in orthologous pairs and compared such within-species variability with their degree of conservation between flies and humans. We observed that a significant number of proteins associated with mRNA translation are highly conserved between species and yet are highly variable within each species. The fact that we observe this in two species whose lineages separated more than 700 million years ago suggests that this is the result of a very ancient process. We hypothesize that this effect might be attributed to a positive selection for variability of virus-interacting proteins that confers a general resistance to viral hijacking of the mRNA translation machinery within populations. Our analysis points to this and to other processes resulting in positive selection for gene variation.
在进化过程中，变异对于物种的生存和适应至关重要。这种变异是由生化过程的不完美导致的，比如基因突变和DNA序列改变，并且在基因组内通过诸如抗体产生等过程也能观察到。最近的测序项目已经产生了人类和果蝇（黑腹果蝇）基因组的多个版本。这些使我们有机会研究个体基因序列在物种内部以及物种之间是如何变化的。在这里，我们将人类和果蝇的基因排列成直系同源对，并比较了这种物种内部的变异性与其在果蝇和人类之间的保守程度。我们观察到，大量与mRNA翻译相关的蛋白质在物种之间高度保守，但在每个物种内部却高度可变。我们在两个谱系分化超过7亿年的物种中观察到这一现象，这表明这是一个非常古老过程的结果。我们推测这种效应可能归因于对病毒相互作用蛋白变异性的正向选择，这种选择赋予了群体对病毒劫持mRNA翻译机制的普遍抗性。我们的分析指出了这一点以及导致基因变异正向选择的其他过程。
