College of Life Science, Shaanxi Normal University, Xi'an 710119, China.
College of Life Science, Shaanxi Normal University, Xi'an 710119, China.
Aquat Toxicol. 2022 Aug;249:106228. doi: 10.1016/j.aquatox.2022.106228. Epub 2022 Jun 16.
Nitrite is a ubiquitous toxic compound in aquatic ecosystems and has negative effects on aquatic organisms. The intestine and the trillions of microbes that inhabit it, play an integral role in maintaining digestive and immune functions. However, the effects of nitrite on intestinal health and microflora have been poorly investigated. Therefore, the present study evaluated the response of intestinal histology, immunity, digestive enzyme activities and microbiota to nitrite exposure in Bufo gargarizans tadpoles. The results showed that nitrite caused damage to the intestine and impaired digestive performance. Significant changes in the transcriptional profiles of genes involved in oxidative stress (sod, gpx and hsp), inflammation, and immunity (socs3, il-27, il-1β and il-17d) were observed in the NO-N treatment groups. In addition, exposure to nitrite induced alterations of intestinal microbial diversity, structure and composition, suggesting that nitrite may lead to intestinal microbiota dysbiosis. It is noteworthy that probiotics (e.g., Bacteroidetes and Fusobacteria) were decreased after exposure to nitrite, whereas potentially opportunistic pathogens such as Proteobacteria and Enterobacteriaceae were elevated. Functional prediction and correlation analysis suggested that the above changes may interfere with metabolic function and trigger various diseases. Taken together, we concluded that nitrite exposure induced intestinal microbial dysbiosis, which may lead to immune dysfunction and metabolic disorder, and ultimately to histological damages in B. gargarizans. Further, this study will provide a scientific basis for further understanding the risk of nitrite pollution on the intestinal health of amphibians.
亚硝酸盐是水生生态系统中普遍存在的有毒化合物，对水生生物有负面影响。肠道及其栖息的数万亿微生物在维持消化和免疫功能方面发挥着重要作用。然而，亚硝酸盐对肠道健康和微生物群的影响还没有得到充分的研究。因此，本研究评估了亚硝酸盐暴露对中华大蟾蜍蝌蚪肠道组织学、免疫、消化酶活性和微生物群的影响。结果表明，亚硝酸盐对肠道造成损伤，损害消化性能。NO-N 处理组中与氧化应激（sod、gpx 和 hsp）、炎症和免疫（socs3、il-27、il-1β和 il-17d）相关的基因转录谱发生显著变化。此外，亚硝酸盐暴露诱导肠道微生物多样性、结构和组成发生改变，表明亚硝酸盐可能导致肠道微生物失调。值得注意的是，暴露于亚硝酸盐后，益生菌（如拟杆菌门和梭杆菌门）减少，而潜在的机会性病原体如变形菌门和肠杆菌科增加。功能预测和相关性分析表明，上述变化可能干扰代谢功能并引发各种疾病。综上所述，我们得出结论，亚硝酸盐暴露诱导肠道微生物失调，可能导致免疫功能障碍和代谢紊乱，最终导致 B. gargarizans 的组织学损伤。此外，本研究将为进一步了解亚硝酸盐污染对两栖动物肠道健康的风险提供科学依据。
