Université de Reims Champagne-Ardenne, INERIS-SEBIO UMR I-02, Reims, France.
Université de Reims Champagne-Ardenne, INERIS-SEBIO UMR I-02, Reims, France.
Aquat Toxicol. 2021 Jan;230:105699. doi: 10.1016/j.aquatox.2020.105699. Epub 2020 Nov 22.
Metal trace elements such as cadmium (Cd) are commonly present in ecosystems and could lead to impairment of mitochondrial functions and energy imbalance in aquatic organisms including molluscs. Combined exposure to increasing temperatures and Cd could enhance such an impact on animals. Seasonal fluctuations, such as temperature, and the corresponding reproduction cycle can affect biomarker responses. However, the reproduction cycle stage is rarely taken into account in ecotoxicological studies. Thus, this work aimed at understanding energy metabolism responses in a sentinel species, Dreissena polymorpha. Mussels were collected during the rest and the reproduction periods and were exposed to 10 μg.L of cadmium (Cd) at two temperatures (in situ temperature and in situ temperature + 5°C) during 7 days. Energy metabolism was monitored by measuring reserves and energy nucleotides charge and by assessing aerobic and anaerobic metabolism markers, and upstream regulation pathways. Markers related to OXPHOS activity revealed seasonal variations under laboratory conditions. Conversely, adenylate nucleotides, glycogen, lipid and transcript levels of AMP-activated protein kinase, citrate synthase, ATP synthase and cytochrome b encoding genes remained steady after the acclimation period. No evident effect of Cd on energy metabolism markers was noticed for both exposures although the transcript level of succinate dehydrogenase and citrate synthase encoding genes decreased with Cd during the rest period. Cellular stress, revealed by lipid peroxidation and catalase mRNA levels, only occurred in Cd and warming co-exposed mussels during the reproduction period. These results suggest that contaminant impact might differ according to the reproduction cycle stage. The effect of confounding factors on biomarker variations should be further investigated to have a deeper knowledge of metabolism responses under laboratory conditions.
金属微量元素如镉 (Cd) 普遍存在于生态系统中，可能导致包括软体动物在内的水生生物的线粒体功能受损和能量失衡。温度升高和 Cd 的联合暴露可能会增强这种对动物的影响。季节性波动，如温度，以及相应的繁殖周期，会影响生物标志物的反应。然而，在生态毒理学研究中，很少考虑繁殖周期阶段。因此，这项工作旨在了解指示物种多形蜉蝣（ Dreissena polymorpha ）的能量代谢反应。贻贝在休息和繁殖期间采集，并在两个温度（原位温度和原位温度+5°C）下暴露于 10 μg.L 的 Cd 中 7 天。通过测量储备和能量核苷酸电荷，以及评估有氧和无氧代谢标志物以及上游调节途径，监测能量代谢。在实验室条件下，与 OXPHOS 活性相关的标志物显示出季节性变化。相反，在适应期后，腺嘌呤核苷酸、糖原、脂质和 AMP 激活蛋白激酶、柠檬酸合酶、ATP 合酶和细胞色素 b 编码基因的转录水平保持稳定。尽管在休息期间 Cd 降低了琥珀酸脱氢酶和柠檬酸合酶编码基因的转录水平，但两种暴露方式对能量代谢标志物都没有明显的影响。只有在繁殖期间，Cd 和升温共暴露的贻贝中，细胞应激（由脂质过氧化和过氧化氢酶 mRNA 水平揭示）才会发生。这些结果表明，污染物的影响可能因繁殖周期阶段而异。应进一步研究混杂因素对生物标志物变化的影响，以更深入地了解实验室条件下的代谢反应。
