环境微塑料暴露引起斑马鱼肠道菌群失调导致行为和代谢紊乱的机理研究

The potential for the exposure of humans and wildlife to environmental pollutants has been increasing in recent years. There is growing evidence of a major increase in impacts of the environmental pollutants gut microbiota and metabolism. Microplastics is one kind of the most common pollutants in the environment, and they are widely present in sediment, soil, water, suggesting that the number of humans and wildlife suffering potential exposure to them is increasing. The enviromental risk assessments for microplastics are primarily based on detecting the real concentrations in the sediment and water in the revier and sea or the main endpoints related to the reprodective system in some different aquatic animals. However, effects of microplastics on gut microbiome, locomotor behavior and metablism in aqutic animals have only received limited attention. In this study,we want to indentify whether the exposure to microplastics have impacts on the gut microflora in zebrafish, thus contributing to partially explain increased prevalence of the locomotor behavior and metabolism disorder. Here,the effects of the exposure to two different microplastics including polystyrene and polyphenylene on the gut microbiota, inflammation, behavior, and metabolism will be evaluated on physiological and molecular levels. In addition, we also want to develop a new kind of germ free larval zebrafish to determine wether the microplastics can induce the locomotor behavior and metabolism disorder by changing the gut microbiota composition. All the information being obtained in this study is intended to provide new insights into how the environmental microplastics induce the toxicity such as gut microbiota dysbiosis and metabolism disorder in aquatic organisms.

环境污染物暴露引起生物肠道菌群失调及其诱导的生理变化和病理发生是当今环境毒理与健康领域的研究热点之一。微塑料是我国环境中最常见的污染物之一，广泛存在于底泥、土壤和水环境中，并在局部区域中达到较高的浓度。微塑料可通过各种途径或单一或联合其它污染物暴露环境生物甚至人群。由于微塑料很难被降解，可长时间存在于肠道中，对健康产生极大的影响，但目前关于环境微塑料引起的生物毒理效应还未引起大家的关注。本项目拟通过用不同颗粒大小的聚苯乙烯和聚乙烯微塑料对斑马鱼成鱼和幼鱼进行不同条件的暴露，在组织、生理以及分子水平上探讨微塑料对肠道组织与细胞的损伤及功能的影响、对肠道菌群的结构的影响以及与肠道微生物的互作效应，进一步通过建立的无菌斑马鱼幼鱼论证该两种微塑料通过引起肠道菌群的失调而导致行为和代谢紊乱的机理，研究结果可为评价环境相关浓度不同大小（纳米至微米级）和种类的微塑料对水生生物的毒理提供新的证据。

微塑料（Microplastics，MPs）作为一种新型的污染物，在环境中无处不在，近年受到了极其广泛的关注。据统计发现，聚苯乙烯微塑料（Polystyrene microplastics，PS-MPs）和聚乙烯微塑料（PE-MPs）在环境中的所占的比例最高，是环境中常见的MPs。大量的研究证实MPs对生物和环境会带来许多的负面影响，但关于MPs对水生生物肠道菌群及代谢相关的影响还未明确。本研究使用不同浓度不同粒径的2种MPs的对不同发育阶段的斑马鱼进行暴露，通过对生理生化等相关指标进行检测，并重点解析PS-和PE-MPs对斑马鱼肠道菌群和代谢的影响，并通过构建无菌斑马鱼来验证相关结果。研究发现不同粒径和浓度的PS-和PE-MPs在斑马鱼幼鱼以及成鱼中肠道等组织中可以蓄积，并对斑马鱼的行为产生影响，高浓度MPs处理会降低斑马鱼的游泳速度。通过16S RNA测序和非靶向代谢组学分析发现，PS-和PE-MPs暴露会引起斑马鱼幼鱼菌群的失调，主要表现为降低了斑马鱼肠道微生物的丰度和多样性，并对斑马鱼的代谢产生显著的影响，但不同的MPs之间具有显著的差异，表现为PS-MPs主要影响斑马鱼的糖代谢与氨基酸代谢，PE-MPs主要影响斑马鱼的磷脂类物质的代谢，并且与一些肠道微生物的变化具一定的相关性。同时，2种MPs暴露还对幼鱼造成神经发育毒性、免疫毒性、氧化损伤等毒理效应，也可以影响成鱼的生长发育和肝脏代谢，产生一定的毒理效应，这可能和肠道菌群的失调和代谢的改变密切相关，但具体的机制还需要进一步的验证。有趣的是，我们后续实验也进一步表明微塑料暴露也可以对小鼠的肠道菌群和代谢产生显著的影响，并具有明显的传代效应。总的来说，本研究的结果表明，微塑料对水生生物的影响不容忽视，肠道菌群和代谢可以作为评价MPs的健康风险的靶标。