International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, 201306, China.
University of Geneva, Faculty of Sciences, Earth and Environment Sciences, Department F.A. Forel for Environmental and Aquatic Sciences, CH-1211, Geneva, Switzerland.
Chemosphere. 2024 Sep;364:143260. doi: 10.1016/j.chemosphere.2024.143260. Epub 2024 Sep 3.
Global climate change is a major trigger of unexpected temperature fluctuations. The impacts of marine heatwaves (MHWs) and nano-titanium dioxide (nano-TiO) on marine organisms have been extensively investigated. However, the potential mechanisms underlying their interactive effects on physiological processes and metabolism remain poorly understood, especially regarding periodic MHWs in real-world conditions. In this study, the effects of nano-TiO (at concentrations of 0, 25, and 250 μg/L) and periodic MHWs on the condition index (CI) and underlying metabolic mechanisms were investigated in mussels (Mytilus coruscus). The results showed that mussels try to upregulate their respiration rate (RR) to enhance aerobic metabolism (indicated by elevated succinate dehydrogenase) under short-term nano-TiO exposure. However, even at ambient concentration (25 μg/L), prolonged nano-TiO exposure inhibited ingestion ability (decreased clearance rate) and glycolysis (inhibited pyruvate kinase, hexokinase, and phosphofructokinase activities), which led to an insufficient energy supply (decreased triglyceride, albumin, and ATP contents). Repeated thermal scenarios caused more severe physiological damage, demonstrating that mussels are fragile to periodic MHWs. MHWs decreased the zeta potential of the nano-TiO particles but increased the hydrodynamic diameter. Additionally, exposure to nano-TiO and periodic MHWs further affected aerobic respiration (inhibited lactate dehydrogenase and succinate dehydrogenase activities), metabolism (decreased RR, activities of respiratory metabolism-related enzymes, and expressions of PEPCK, PPARγ, and ACO), and overall health condition (decreased ATP and CI). These findings indicate that the combined stress of these two stressors exerts more detrimental impact on the physiological performance and energy metabolism of mussels, and periodic MHWs exacerbate the toxicological effects of ambient concentration nano-TiO. Given the potential worsening of nanoparticle pollution and the increase in extreme heat events in the future, the well-being of mussels in the marine environment may face further threats.
全球气候变化是导致温度异常波动的主要因素之一。海洋热浪（MHWs）和纳米二氧化钛（nano-TiO）对海洋生物的影响已得到广泛研究。然而，它们对生理过程和代谢的相互作用的潜在机制仍知之甚少，特别是在现实条件下周期性海洋热浪方面。在这项研究中，研究了纳米 TiO（浓度分别为 0、25 和 250μg/L）和周期性海洋热浪对贻贝（Mytilus coruscus）条件指数（CI）和潜在代谢机制的影响。结果表明，贻贝在短期纳米 TiO 暴露下，试图通过上调呼吸速率（RR）来增强有氧代谢（通过琥珀酸脱氢酶升高来指示）。然而，即使在环境浓度（25μg/L）下，长时间的纳米 TiO 暴露也会抑制摄食能力（降低清除率）和糖酵解（抑制丙酮酸激酶、己糖激酶和磷酸果糖激酶的活性），导致能量供应不足（降低甘油三酯、白蛋白和 ATP 含量）。重复的热场景造成了更严重的生理损伤，表明贻贝对周期性海洋热浪非常脆弱。海洋热浪降低了纳米 TiO 颗粒的zeta 电位，但增加了水动力直径。此外，暴露于纳米 TiO 和周期性海洋热浪进一步影响有氧呼吸（抑制乳酸脱氢酶和琥珀酸脱氢酶的活性）、代谢（降低 RR、呼吸代谢相关酶的活性以及 PEPCK、PPARγ 和 ACO 的表达）和整体健康状况（降低 ATP 和 CI）。这些发现表明，这两种胁迫因素的联合胁迫对贻贝的生理表现和能量代谢产生了更不利的影响，周期性海洋热浪加剧了环境浓度纳米 TiO 的毒理学效应。考虑到未来纳米颗粒污染的潜在恶化和极端高温事件的增加，海洋环境中贻贝的福祉可能会面临进一步的威胁。
