Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.
Department of Genetics, Wuhan University, Wuhan 430071, China.
Sci Total Environ. 2022 Oct 1;841:156571. doi: 10.1016/j.scitotenv.2022.156571. Epub 2022 Jun 8.
Microplastics (MPs) pollution has been recognized as a threat to sustainable fisheries due to the risks of MPs contamination in the process of feed production and susceptibility of fish to ingest MPs from the aquatic environment. In this study, we applied comprehensive approaches to investigate the impacts of polyethylene microplastics (PE-MPs) on juvenile genetically improved farmed tilapia (GIFT, Oreochromis niloticus) through 9-week dietary exposure based on growth performance, gut microbiota, liver metabolism, and gene expressions in brain and liver tissues. Dietary exposure to two kinds of PE-MPs with different median size (27 μm and 63 μm, respectively) concentration-dependently decreased weight gain (WG), while increased feed conversion ratio (FCR) and hepatosomatic index (HSI) of the tilapia. Dietary administration of PE-MPs also significantly reduced the activities of intestinal protease and amylase. PE-MPs particles of the larger size groups (63 μm) were mainly detected in feces, but those of the smaller ones (27 μm) tended to be accumulated in intestine. PE-MPs ingestion resulted in the alteration of gut microbiota composition, with Fusobacteria, Verrucomicrobia and Firmicutes as the overrepresented bacterial taxa. Metabolomic assays of liver samples in fish fed the diets containing 8 % of PE-MPs revealed the particle size-specific variations in composition of differential metabolites and metabolism pathways such as amino acid and glycerophospholipid metabolism. Gene expressions of brain and liver samples were analyzed by RNA-seq. Photoperiodism and circadian rhythm were the representative biological processes enriched for the differentially expressed genes (DEGs) identified from the brain. Citrate cycle (TCA cycle) was the most enriched pathway revealed by a joint transcriptomic and metabolic pathway analysis for the liver, followed by propanoate and pyruvate metabolism. Furthermore, an integration analysis of the gut microbiome and liver transcriptome data identified significant associations between several pathogenic bacteria taxa and immune pathways. Our findings demonstrated that the sizes and concentrations of PE-MPs are critically related to their toxic impacts on microbiota community, metabolism, gene expressions and thus fish growth.
微塑料（MPs）污染已被认为是对可持续渔业的威胁，因为在饲料生产过程中存在 MPs 污染的风险，而且鱼类容易从水生环境中摄入 MPs。在这项研究中，我们应用综合方法，通过 9 周的饮食暴露，研究了聚乙烯微塑料（PE-MPs）对幼龄遗传改良罗非鱼（GIFT，Oreochromis niloticus）的影响，基于生长性能、肠道微生物群、肝脏代谢以及脑和肝脏组织中的基因表达。两种不同中值大小（分别为 27μm 和 63μm）的 PE-MPs 浓度依赖性地降低了罗非鱼的增重（WG），同时增加了饲料转化率（FCR）和肝体比（HSI）。饮食中添加 PE-MPs 还显著降低了肠道蛋白酶和淀粉酶的活性。较大粒径组（63μm）的 PE-MPs 颗粒主要在粪便中检测到，而较小粒径组（27μm）的颗粒则倾向于在肠道中积累。PE-MPs 的摄入导致肠道微生物群组成发生改变，其中厚壁菌门、疣微菌门和Firmicutes 为优势细菌门。对摄食含 8%PE-MPs 饮食的鱼的肝样品进行代谢组学分析显示，粒径特异性差异代谢物和代谢途径的组成发生变化，如氨基酸和甘油磷脂代谢。通过 RNA-seq 分析脑和肝样品的基因表达。光周期和昼夜节律是从大脑中鉴定的差异表达基因（DEGs）中富集的代表性生物过程。通过联合转录组和代谢途径分析，柠檬酸循环（TCA 循环）是肝脏中最富集的途径，其次是丙酸和丙酮酸代谢。此外，肠道微生物组和肝转录组数据的整合分析确定了几种致病菌与免疫途径之间存在显著关联。我们的研究结果表明，PE-MPs 的大小和浓度与它们对微生物群落、代谢、基因表达以及鱼类生长的毒性影响密切相关。
