PDF(Pubmed)
Abstract：
Regulating transcription allows organisms to respond to their environment, both within a single generation (plasticity) and across generations (adaptation). We examined transcriptional differences in gill tissues of fishes in the Poecilia mexicana species complex (family Poeciliidae), which have colonized toxic springs rich in hydrogen sulfide (H2S) in southern Mexico. There are gene expression differences between sulfidic and non-sulfidic populations, yet regulatory mechanisms mediating this gene expression variation remain poorly studied. We combined capped-small RNA sequencing (csRNA-seq), which captures actively transcribed (i.e. nascent) transcripts, and messenger RNA sequencing (mRNA-seq) to examine how variation in transcription, enhancer activity, and associated transcription factor binding sites may facilitate adaptation to extreme environments. csRNA-seq revealed thousands of differentially initiated transcripts between sulfidic and non-sulfidic populations, many of which are involved in H2S detoxification and response. Analyses of transcription factor binding sites in promoter and putative enhancer csRNA-seq peaks identified a suite of transcription factors likely involved in regulating H2S-specific shifts in gene expression, including several key transcription factors known to respond to hypoxia. Our findings uncover a complex interplay of regulatory processes that reflect the divergence of extremophile populations of P. mexicana from their non-sulfidic ancestors and suggest shared responses among evolutionarily independent lineages.
摘要：
调节转录使生物体对环境做出反应，无论是在一代人(可塑性)还是跨代(适应性)。我们检查了Poeciliamexicana物种复合体（Poeciliidae家族）中鱼的g组织的转录差异，在墨西哥南部定居了富含硫化氢（H2S）的有毒泉水。硫化物和非硫化物种群之间存在基因表达差异，然而，介导这种基因表达变异的调节机制仍然缺乏研究。我们结合了加帽小RNA测序（csRNA-seq），捕获主动转录（即新生）的转录本，和信使RNA测序(mRNA-seq)来检查转录中的变异，增强子活性，和相关的转录因子结合位点可能有助于适应极端环境。csRNA-seq揭示了硫化物和非硫化物种群之间数千个差异启动的转录本，其中许多参与H2S的解毒和反应。对启动子和推定增强子csRNA-seq峰中的转录因子结合位点的分析确定了一系列可能参与调节基因表达中H2S特异性变化的转录因子。包括几种已知对缺氧有反应的关键转录因子。我们的发现揭示了调控过程的复杂相互作用，反映了墨西哥疟原虫极端微生物种群与非硫化物祖先的差异，并暗示了进化独立谱系之间的共同反应。
