Systematic impacts of microplastics exposure

The specific organ toxicity resulting from microplastics (MP) exposure has been extensively explored in relation to the gut, liver, testis, and lung. However, such effects are not confined to specific organs or tissues under real-world conditions. It is intriguing to ascertain whether MP exposure poses a systemic threat to the entire organism, impacting on aspects such as lifespan, sleep and fecundity. In this study, using a terrestrial animal model, Drosophila melanogaster, we showed that two doses of MP (1-5 μm) in the diet led to gut damage, with the particles retained in the digestive system. Life-long MP exposure to adult flies caused a significant reduction in lifespan. Short-term MP exposure already caused disrupted sleep structure in terms of increased sleep episode length during the day. Additionally, a week-long exposure to MP caused a reduction in ovary size, with a trend towards decreased egg-laying in mated females. Although no penetration of MP into the brain or in the ovary was observed, transcriptome analysis of D. melanogaster brains and ovaries showed changed gene expression patterns following MP exposure. In the ovary, Gene Ontology (GO) analysis indicated genotoxic effects on inflammation, circadian regulation, and metabolic process, with significant impacts on extracellular structure-related pathways. In the brain, GO analysis revealed changes in pathways associated with proteolysis and carbohydrate metabolism processes. Our study provides compelling evidence of negative impacts of MP exposure at a systemic level, emphasizing the need to address concerns and implement strategies to mitigate environmental pollution caused by MP.

微塑料（microplastics, MP）暴露所引发的特异性器官毒性，已针对肠道、肝脏、睾丸与肺部开展了大量研究。然而，在真实环境条件下，此类毒性效应并不局限于特定器官或组织。探明微塑料暴露是否会对整个生物体构成全身性威胁，并影响寿命、睡眠与繁殖力，是一个颇具研究价值的科学问题。本研究以陆生模式生物黑腹果蝇（Drosophila melanogaster）为研究对象，结果显示，日粮中添加的两种剂量1~5微米级微塑料可引发肠道损伤，且微塑料颗粒会滞留于消化系统内。成年果蝇终身暴露于微塑料环境下，其寿命会显著缩短。短期微塑料暴露即可破坏睡眠结构，表现为日间睡眠片段时长延长。此外，为期一周的微塑料暴露会导致雌性果蝇卵巢体积缩小，且交配雌蝇的产卵量呈现下降趋势。尽管未观察到微塑料渗透进入果蝇大脑或卵巢组织，但对黑腹果蝇大脑与卵巢的转录组分析显示，微塑料暴露后二者的基因表达模式均发生了改变。在卵巢组织中，基因本体（Gene Ontology, GO）富集分析显示，微塑料暴露引发了与炎症、昼夜节律调控及代谢过程相关的遗传毒性效应，并对细胞外结构相关通路产生了显著影响。在大脑组织中，GO分析则揭示了与蛋白水解及碳水化合物代谢过程相关的通路发生改变。本研究为微塑料暴露在全身层面带来的负面影响提供了确凿证据，凸显了正视公众关切并制定策略以缓解微塑料造成的环境污染的必要性。