咪唑类离子液体长期暴露对鲤肠道形态、氧化应激、免疫和肠道菌群的影响

IMIDAZOLES IONIC LIQUIDS([C_(6)mim]Cl,[C_(8)mim]Cl,[C_(12)mim]Cl)ON INTESTINAL MORPHOLOGY,OXIDATIVE STRESS IMMUNITY AND INTESTINAL MICROFLORA OF COMMON CARP(CARPIO CARPIO L.)

以鲤(Cyprinus carpio L.)为受试对象,探究3种不同烷基链咪唑类离子液体(Alkyl ionic liquids,AILs)([C6mim]Cl、[C8mim]Cl和[C_(12)mim]Cl,暴露浓度分别为4.97、2.15和0.09 mg/L)对鲤肠道的毒性作用。结果表明随烷基链长度增加,与对照组(NC)相比(1)鲤肠绒毛高度和肌层厚度显著降低(P<0.05);(2)[C8mim]Cl组T-AOC水平显著性升高(P<0.05);[C_(12)mim]Cl组GSH-Px、LDH、ACP酶活性和T-AOC水平显著性升高(P<0.05);(3)促炎因子IL-6、IL-8基因表达量显著升高(P<0.05),[C_(12)mim]Cl组尤为明显;(4)[C6mim]Cl和[C_(12)mim]Cl组鲤肠道菌群Chao1和Ace指数显著升高(P<0.05)。PCoA和UPGMA聚类分析结果表明3种AILs暴露改变了鲤肠道菌群组成。[C8mim]Cl和[C_(12)mim]Cl组有益菌厚壁菌门(Firmicutes)丰度显著降低(P<0.05)。3种AILs暴露均使黄杆菌属(Flavobacterium)等致病菌丰度显著增加(P<0.05),鲸杆菌属(Cetobacterium)等有益菌丰度降低。PICRUSt2菌群功能预测分析发现,[C6mim]Cl、[C_(12)mim]Cl组辅助因子和维生素代谢、外源生物降解和代谢等与碳氮循环功能相关途径丰度升高。综上,不同烷基链AILs暴露均可造成鲤肠道组织形态改变、氧化应激和免疫损伤,改变肠道菌群结构,且毒性随烷基链长度增加呈一定上升趋势。研究结果将为不同烷基链AILs对鱼类肠道的生态毒性机制研究提供一定的理论依据。

Alkyl ionic liquids(AILs)are considered to be green organic solvents,but recent studies have revealed their potential ecotoxicity,which is influenced by the length of alkyl chains.The fish gut serves as a vital mechanical and immune barrier against exposure to environmental toxins,necessitating further investigation into the toxicity of different alkyl chains on the fish gut microecosystems.Therefore,in order to explore the toxic effects of three different AILs([C_(6)mim]Cl,[C_(8)mim]Cl,[C_(12)mim]Cl)on intestinal of Cyprinus carpio L.,a total of 360 carps were allocated into 4 groups with 3 replicates of 30 fishes each,with the long exposure concentrations of[C_(6)mim]Cl,[C_(8)mim]Cl and[C_(12)mim]Cl(the exposure concentrations were 4.97,2.15 and 0.09 mg/L respectively)for 30d.The results are as follows:(1)As the alkyl chain length increased,the intestinal villus height and muscle thickness of carps decreased significantly(P<0.05);(2)The[C_(8)mim]Cl group exhibited a significant increase in T-AOC level(P<0.05);The[C_(12)mim]Cl group increased significantly in levels of GSH-Px,LDH,ACP and T-AOC(P<0.05);(3)The expressions of proinflammatory cytokines IL-6 and IL-8 mRNA were significantly increased(P<0.05),particularly in the[C_(12)mim]Cl group;(4)Sequencing results showed that the microbial Chao1 and Ace indices of[C_(6)mim]Cl and[C_(12)mim]Cl groups were significantly increased(P<0.05).The results of PCoA and UPGMA cluster analysis showed that the three AILs exposures changed the intestinal flora composition of the carp.The abundance of Firmicutes which was considered as probiotic bacteria in[C_(8)mim]Cl and[C_(12)mim]Cl groups decreased significantly(P<0.05).In all the AILs exposure groups,the abundance of pathogenic bacteria such as Flavobacterium increased significantly(P<0.05),while the abundance of beneficial bacteria such as Cetobacterium decreased.In conclusion,different alkyl chains exposure can cause the damage of intestinal morphology,induce oxidative stress and immune imbalance,and change the intestinal flora structure in carp.The prediction analysis of PICRUSt2 flora function showed that the abundance of pathways related to intestinal flora metabolism in[C_(6)mim]Cl and[C_(12)mim]Cl groups increased.In total,this study revealed that the toxicity on the intestinal of carp with increasing alkyl chain length,thereby enhancing understanding of the mechanism by which AILs with different alkyl chain lengths exert toxicity on fish in aquatic ecosystem.