Data from: Early and late response of Nematostella vectensis transcriptome to heavy metals

Environmental contamination from heavy metals poses a global concern for the marine environment, as heavy metals are passed up the food chain and persist in the environment long after the pollution source is contained. Cnidarians play an important role in shaping marine ecosystems, but environmental pollution profoundly affects their vitality. Among the cnidarians, the sea anemone Nematostella vectensis is an advantageous model for addressing questions in molecular ecology and toxicology as it tolerates extreme environments and its genome has been published. Here we employed a transcriptome-wide RNA-Seq approach to analyze N.vectensis molecular defense mechanisms against four heavy metals: Hg, Cu, Cd and Zn. Altogether, more than 4800 transcripts showed significant changes in gene expression. Hg had the greatest impact on up-regulating transcripts, followed by Cu, Zn and Cd. We identified, for the first time in Cnidaria, co-up-regulation of immediate-early transcription factors such as Egr1, AP1 and NF-κB. Time-course analysis of these genes revealed their early expression as rapidly as one hour after exposure to heavy metals, suggesting that they may complement or substitute for the roles of the metal mediating Mtf1 transcription factor. We further characterized the regulation of a large array of stress-response gene families including Hsp, ABC, CYP members and phytochelatin synthase that may regulate synthesis of the metal-binding phytochelatins instead of the methallothioneins that are absent from Cnidaria genome. This study provides mechanistic insight into heavy-metal toxicity in N.vectensis and sheds light on ancestral stress adaptations.

重金属污染正对全球海洋环境构成严峻威胁——重金属可沿食物链逐级富集，并在污染源被管控后仍能在环境中长期留存。刺胞动物（Cnidaria）在海洋生态系统的构建中发挥着关键作用，而环境污染会严重损害其生存活力。在刺胞动物类群中，星状海葵（Nematostella vectensis）是开展分子生态学与毒理学研究的优势模型物种：它能够耐受极端环境，且其基因组已完成测序并公开。本研究采用全转录组RNA测序（RNA-Seq）技术，分析了星状海葵应对四种重金属——汞（Hg）、铜（Cu）、镉（Cd）与锌（Zn）——的分子防御机制。共计有超过4800个转录本（transcript）的基因表达量发生显著变化。其中汞（Hg）对转录本上调的影响最为显著，其次依次为铜（Cu）、锌（Zn）与镉（Cd）。本研究首次在刺胞动物中发现，即刻早期转录因子（immediate-early transcription factors）如Egr1、AP1与NF-κB存在协同上调现象。对这些基因的时序表达分析显示，它们在暴露于重金属后最快1小时即可启动表达，这表明它们或可补充甚至替代金属调节转录因子Mtf1的功能。本研究进一步解析了大量应激响应基因家族的调控机制，涵盖热休克蛋白（Hsp）家族、ATP结合盒转运蛋白（ABC）家族、细胞色素P450（CYP）家族成员，以及植物螯合肽合酶；这类基因可通过调控金属结合型植物螯合肽的合成，弥补刺胞动物基因组中缺乏金属硫蛋白的缺陷。本研究不仅阐明了星状海葵应对重金属毒性的分子机制，同时为解析古老后生动物的应激适应演化提供了全新见解。