Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, 32611, USA; Inner Mongolia Key Laboratory of Environmental Pollution Control & Waste Resource Reuse, School of Ecology and Environment, Inner Mongolia University, Hohhot, 010021, China.
Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, 32611, USA; Masaryk University, Research Centre for Toxic Compounds in the Environment (RECETOX), Brno, Czech Republic.
Environ Pollut. 2021 Jan 1;268(Pt B):115715. doi: 10.1016/j.envpol.2020.115715. Epub 2020 Oct 5.
Dietary exposure to chemicals alters the diversity of microbiome communities and can lead to pathophysiological changes in the gastrointestinal system. The organochlorine pesticide dieldrin is a persistent environmental contaminant that bioaccumulates in fatty tissue of aquatic organisms. The objectives of this study were to determine whether environmentally-relevant doses of dieldrin altered gastrointestinal morphology and the microbiome of zebrafish. Adult zebrafish at ∼4 months of age were fed a measured amount of feed containing either a solvent control or one of two doses of dieldrin (measured at 16, and 163.5 ng/g dry weight) for 4 months. Dieldrin body burden levels in zebrafish after four-month exposure were 0 (control), 11.47 ± 1.13 ng/g (low dose) and 18.32 ± 1.32 ng/g (high dose) wet weight [mean ± std]. Extensive histopathology at the whole organism level revealed that dieldrin exposure did not induce notable tissue pathology, including the gastrointestinal tract. A repeated measure mixed model analysis revealed that, while fish gained weight over time, there were no dieldrin-specific effects on body weight. Fecal content was collected from the gastrointestinal tract of males and 16S rRNA gene sequencing conducted. Dieldrin at a measured feed dose of 16 ng/g reduced the abundance of Firmicutes, a phylum involved in energy resorption. At the level of class, there was a decrease in abundance of Clostridia and Betaproteobacteria, and an increase in Verrucomicrobiae species. We used a computational approach called predicted relative metabolomic turnover (PRMT) to predict how a shift in microbial community composition affects exchange of metabolites. Dieldrin was predicted to affect metabolic turnover of uroporphyrinogen I and coproporphyrinogen I [enzyme]-cysteine, hydrogen selenide, selenite, and methyl-selenic acid in the fish gastrointestinal system. These pathways are related to bacterial heme biosynthesis and selenium metabolism. Our study demonstrates that dietary exposures to dieldrin can alter microbiota composition over 4 months, however the long-term consequences of such impacts are not well understood.
饮食中接触化学物质会改变微生物群落的多样性，并导致胃肠道发生病理生理变化。有机氯农药狄氏剂是一种持久的环境污染物，会在水生生物的脂肪组织中生物累积。本研究的目的是确定环境相关剂量的狄氏剂是否会改变斑马鱼的胃肠道形态和微生物组。大约 4 个月大的成年斑马鱼被喂食一定量的饲料，饲料中含有溶剂对照或两种剂量的狄氏剂（分别测量为 16 和 163.5ng/g 干重），持续 4 个月。在 4 个月的暴露后，斑马鱼体内的狄氏剂体负荷水平为 0（对照）、11.47±1.13ng/g（低剂量）和 18.32±1.32ng/g（高剂量）湿重[平均值±标准差]。在整体水平上的广泛组织病理学检查表明，狄氏剂暴露不会引起明显的组织病理学变化，包括胃肠道。重复测量混合模型分析表明，尽管鱼的体重随时间增加，但体重没有受到狄氏剂的特异性影响。从雄性的胃肠道中收集粪便内容物并进行 16S rRNA 基因测序。在 16ng/g 的测量饲料剂量下，狄氏剂降低了厚壁菌门的丰度，厚壁菌门参与能量再吸收。在纲的水平上，梭菌和β变形菌的丰度降低，疣微菌科的丰度增加。我们使用了一种称为预测相对代谢物周转率（PRMT）的计算方法来预测微生物群落组成的变化如何影响代谢物的交换。狄氏剂被预测会影响鱼类胃肠道中尿卟啉原 I 和粪卟啉原 I[酶]-半胱氨酸、氢化硒、亚硒酸盐和甲基硒酸的代谢周转率。这些途径与细菌血红素生物合成和硒代谢有关。我们的研究表明，饮食中接触狄氏剂可以在 4 个月内改变微生物群落的组成，但这种影响的长期后果尚不清楚。
