Brinkmann Bregje W, Beijk Wouter F, Vlieg Redmar C, van Noort S John T, Mejia Jorge, Colaux Julien L, Lucas Stéphane, Lamers Gerda, Peijnenburg Willie J G M, Vijver Martina G
Institute of Environmental Sciences (CML), Leiden University, Leiden, the Netherlands.
Institute of Environmental Sciences (CML), Leiden University, Leiden, the Netherlands.
Aquat Toxicol. 2021 Jan 24;232:105744. doi: 10.1016/j.aquatox.2021.105744.
Teleost fish embryos are protected by two acellular membranes against particulate pollutants that are present in the water column. These membranes provide an effective barrier preventing particle uptake. In this study, we tested the hypothesis that the adsorption of antimicrobial titanium dioxide nanoparticles onto zebrafish eggs nevertheless harms the developing embryo by disturbing early microbial colonization. Zebrafish eggs were exposed during their first day of development to 2, 5 and 10 mg TiO L (NM-105). Additionally, eggs were exposed to gold nanorods to assess the effectiveness of the eggs' membranes in preventing particle uptake, localizing these particles by way of two-photon microscopy. This confirmed that particles accumulate onto zebrafish eggs, without any detectable amounts of particles crossing the protective membranes. By way of particle-induced X-ray emission analysis, we inferred that the titanium dioxide particles could cover 25-45 % of the zebrafish egg surface, where the concentrations of sorbed titanium correlated positively with concentrations of potassium and correlated negatively with concentrations of silicon. A combination of imaging and culture-based microbial identification techniques revealed that the adsorbed particles exerted antimicrobial effects, but resulted in an overall increase of microbial abundance, without any change in heterotrophic microbial activity, as inferred based on carbon substrate utilization. This effect persisted upon hatching, since larvae from particle-exposed eggs still comprised higher microbial abundance than larvae that hatched from control eggs. Notably, pathogenic aeromonads tolerated the antimicrobial properties of the nanoparticles. Overall, our results show that the adsorption of suspended antimicrobial nanoparticles on aquatic eggs can have cascading effects across different life stages of oviparous animals. Our study furthermore suggests that aggregation dynamics may occur that could facilitate the dispersal of pathogenic bacteria through aquatic ecosystems.
硬骨鱼胚胎受到两层无细胞膜的保护，免受水柱中存在的颗粒污染物的侵害。这些膜提供了一个有效的屏障，防止颗粒的摄取。在本研究中，我们测试了这样一个假设：抗菌二氧化钛纳米颗粒吸附到斑马鱼卵上，仍然会通过干扰早期微生物定殖而损害发育中的胚胎。斑马鱼卵在发育的第一天暴露于2、5和10 mg TiO₂/L（NM-105）中。此外，将卵暴露于金纳米棒中，以评估卵膜在防止颗粒摄取方面的有效性，并通过双光子显微镜对这些颗粒进行定位。这证实了颗粒会聚集在斑马鱼卵上，没有任何可检测到的颗粒穿过保护膜。通过颗粒诱导X射线发射分析，我们推断二氧化钛颗粒可以覆盖斑马鱼卵表面的25%-45%，吸附的钛的浓度与钾的浓度呈正相关，与硅的浓度呈负相关。成像和基于培养的微生物鉴定技术相结合表明，吸附的颗粒具有抗菌作用，但导致微生物丰度总体增加，而异养微生物活性没有任何变化，这是根据碳底物利用情况推断出来的。这种影响在孵化后仍然存在，因为来自暴露于颗粒的卵的幼虫仍然比来自对照卵孵化的幼虫具有更高的微生物丰度。值得注意的是，致病性气单胞菌耐受纳米颗粒的抗菌特性。总体而言，我们的结果表明，悬浮的抗菌纳米颗粒在水生卵上的吸附可能对卵生动物的不同生命阶段产生连锁反应。我们的研究还表明，可能会发生聚集动态，这可能会促进病原菌在水生生态系统中的传播。
