Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, D-14195 Berlin, Germany.
J Fish Biol. 2012 Apr;80(4):785-801. doi: 10.1111/j.1095-8649.2012.03220.x. Epub 2012 Feb 23.
This study evaluated variation in expression of 11 genes within and among six wild populations of the black-chinned tilapia Sarotherodon melanotheron distributed along a salinity gradient from 0 to 100. Previous laboratory studies had shown that expression of these genes was sensitive to water salinity; the current study confirmed that a number of them also varied in expression in wild populations along the salinity gradient. Principal component analysis (PCA) first distinguished two, not mutually exclusive, sets of genes: trade-off genes that were highly expressed at one or other extreme of the salinity gradient and stress genes that were up-regulated at the two salinity extremes (i.e. a U-shaped expression pattern). The PCA clearly partitioned the populations into three groups based on their gene expression patterns and their position along the salinity gradient: a freshwater (GL; 0) population, four brackish and seawater (GB, HB, SM, SF; ranging from 20 to 50) populations and a hypersaline (SK, 100) population. Individual variation in gene expression was significantly greater within the populations at the extreme compared to intermediate salinities. These results reveal phenotypically plastic regulation of gene expression in S. melanotheron, and greater osmoregulatory and plasticity costs at extreme salinities, where fitness-related traits are known to be altered.
本研究评估了分布在 0 至 100 盐度梯度的六个野生黑唇罗非鱼 Sarotherodon melanotheron 群体中 11 个基因的表达变化。先前的实验室研究表明，这些基因的表达对水盐度敏感；本研究证实，其中一些基因在野生种群中也随着盐度梯度的变化而表达。主成分分析（PCA）首先区分了两组非互斥的基因：在盐度梯度的一个或另一个极端高度表达的权衡基因和在两个盐度极端上调的应激基因（即 U 型表达模式）。PCA 根据基因表达模式及其在盐度梯度上的位置，将种群清晰地分为三组：一个淡水（GL；0）种群、四个半咸水和海水（GB、HB、SM、SF；范围从 20 到 50）种群和一个高盐（SK，100）种群。与中间盐度相比，在种群的极端盐度下，基因表达的个体变异显著更大。这些结果揭示了 S. melanotheron 中表型可塑性的基因表达调控，以及在极端盐度下更高的渗透调节和可塑性成本，已知这些成本会改变与适应性相关的特征。
