Data from: Adaptive differences in gene expression associated with heavy metal tolerance in the soil arthropod Orchesella cincta

Field-selected tolerance to heavy metals has been reported for Orchesella cincta (Arthropoda: Collembola) populations occurring at metal-contaminated mining sites. This tolerance is correlated with heritable increase of metal excretion efficiency; less pronounced cadmium (Cd) induced growth reduction and, over-expression of the metallothionein gene. We applied transcriptomics to determine differential gene expression caused by this abiotic stress in reference and Cd tolerant populations. Many cDNAs responded to Cd exposure in the reference population. Significantly fewer clones were Cd responsive in tolerant animals. Analysis of variance revealed transcripts that interact between Cd exposure and population. Hierarchical cluster analysis of these clones identified two major groups. The first one contained cDNAs that were up regulated by Cd in the reference culture, but non-responsive or down regulated in tolerant animals. This cluster was also characterized by elevated constitutive expression in the tolerant population. Gene ontology analysis revealed that these cDNAs were involved in structural integrity of the cuticle, anti-microbial defense, calcium-channel blocking, sulfur assimilation and chromatin remodeling. The second group consisted of cDNAs down regulated in reference animals but not responding or slightly up regulated in tolerant animals. Their functions involved carbohydrate metabolic processes, Ca2+ dependent stress signaling, redox state, proteolysis and digestion. The reference population showed a strong signature of stress-induced genome-wide perturbation of gene expression, whereas the tolerant animals maintained normal gene expression upon Cd exposure. We confirmed the micro-evolutionary processes occurring in soil arthropod populations and suggest a major contribution of gene regulation to the evolution of a stress-adapted phenotype.已有研究报道，栖息于重金属污染矿区的长角跳虫（Orchesella cincta，节肢动物门：弹尾纲）种群对重金属具有野外筛选获得的耐受性。该耐受性与金属排泄效率的可遗传提升、镉（Cd）诱导的生长抑制程度减轻以及金属硫蛋白（metallothionein）基因的过表达显著相关。本研究采用转录组学（transcriptomics）技术，探究参考种群与镉耐受种群在该非生物胁迫下的差异基因表达情况。参考种群中大量互补DNA（cDNA）可响应镉暴露胁迫；而耐受种群中响应镉暴露的转录本克隆数量显著更少。方差分析结果显示，存在部分转录本的表达量同时受镉暴露与种群类型的交互影响。对这些转录本克隆进行系统聚类分析，可将其划分为两大主要类群。第一类群包含的互补DNA在参考种群中可被镉暴露诱导上调，但在耐受种群中无响应或呈现下调表达；该类群同时以耐受种群中较高的组成型表达为特征。基因本体（Gene Ontology, GO）分析显示，该类群的互补DNA参与角质层结构完整性维持、抗菌防御、钙通道阻滞、硫同化以及染色质重塑等生物学过程。第二类群包含的互补DNA在参考种群中被镉暴露下调，但在耐受种群中无响应或仅呈现轻微上调表达。该类群的功能涉及碳水化合物代谢过程、钙离子依赖型胁迫信号通路、氧化还原稳态、蛋白水解以及消化等生理活动。参考种群呈现出显著的胁迫诱导全基因组基因表达扰动特征，而耐受种群在镉暴露条件下可维持正常的基因表达水平。本研究证实了土壤节肢动物种群中存在的微进化过程，并表明基因调控在胁迫适应表型的进化过程中发挥了重要作用。