Lead homeostasis in extremophile earthworms: time and space resolved changes in metal speciation

由于重金属污染的持久性和传播途径，它是一个日益严重的问题。铅等非必需重金属通过模仿钙等必需元素表现出有害效应。因此，铅的生物积累已知会扰乱中枢神经系统的功能，并与神经退行性疾病的早期发病有关。蚯蚓聚集在重金属污染的景观中，进化出了不同的动态平衡机制来进行金属解毒。基于组学的方法可以：为金属毒性的治疗提供线索；改进土壤毒性测试方法；推进土壤蠕虫修复研究；确定蚯蚓量子点的生物合成机制。利用激光消融电感耦合等离子体质谱成像技术，比较了土壤中等剂量铅暴露下耐铅蚯蚓和对照蚯蚓脑和肠道中铅的生物积累模式。金属图谱定性地揭示了几种生物适应，包括：肠道中大量的铅积累(约为对照的30倍)；脑中铅的生物积累较低(约为对照的10倍)；铅精确地固定在指定的储存/解毒组织(肠道中的绿素组织，脑中的神经元细胞体)中。未来的研究将使用成像质量细胞术、单细胞转录和同步辐射来揭示铅解毒的分子机制。

Heavy metal pollution is a growing issue due to its persistency and routes of spread. Non-essential heavy metals such as lead exhibit deleterious effects through mimicry of essential elements e.g. calcium. Thus, lead bioaccumulation is known to disrupt the function of the central nervous system and has been associated with an early onset of neurodegenerative diseases. Earthworms populating heavy metal polluted landscapes have evolved distinct homeostatic mechanisms for metal detoxification. Omics-based approaches may: provide clues for treatment of metal toxicity; improved soil toxicity testing measures; advance soil vermiremediation research; determine mechanisms of earthworm quantum dot biosynthesis. Laser Ablation Inductively Coupled Plasma Mass Spectrometry imaging was used to compare lead bioaccumulation patterns in the brain and the gut of lead-resistant and control earthworms exposed to equal doses of lead in soil. Metallomic maps qualitatively revealed several biological adaptations including: accumulation of phenomenal amounts of lead in the gut (~30X greater than the control); low lead bioaccumulation in the brain (~10X lower than the control); precise lead sequestration into designated storage/detoxifying tissues (chloragogen tissues in gut, neuronal cell bodies in brain). Future studies will employ imaging mass cytometry, single cell transcriptomics, and synchrotron radiation to reveal molecular mechanisms of lead detoxification.