Martino Chiara, Byrne Maria, Roccheri Maria Carmela, Chiarelli Roberto
Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, Building 16, Palermo, 90128, Italy.
School of Life and Environmental Science, University of Sydney, NSW, Australia.
Aquat Toxicol. 2021 Mar;232:105750. doi: 10.1016/j.aquatox.2021.105750. Epub 2021 Jan 21.
Gradual ocean warming and marine heatwaves represent major threats for marine organisms already facing other anthropogenic-derived hazards, such as chemical contamination in coastal areas. In this study, the combined effects of thermal stress and exposure to gadolinium (Gd), a metal used as a contrasting agent in medical imaging which enters the aquatic environment, were investigated in the embryos and larvae of the sea urchin Paracentrotus lividus. Embryos were exposed to six treatments of three temperatures (18 °C, 21 °C, 24 °C) and two Gd concentrations (control: 0 μM; treated: 20 μM). With respect to developmental progression, increased temperature accelerated development and achievement of the larval stage, while Gd-exposed embryos at the control temperature (18 °C) showed a general delay in development at 24 h post-fertilization (hpf), and a stunting effect and impaired skeleton growth at 48 hpf. Elevated temperatures at near-future projections (+3 °C, 21 °C) reduced the negative effects of Gd on development with a lower percentage of abnormality and improved skeleton growth. Combined extreme warming at present-day marine heatwave conditions (+6 °C, 24 °C) and Gd treatment resulted in a lower proportion of embryos reaching the advanced larval stages compared to the 21 °C + Gd. At the molecular level, western blot analysis showed that Gd was the main driver for the induction of heat shock protein (HSP60, HSP70) expression. At 48 hpf, temperature increase was the main driver for activation of additional cellular stress response strategies such as autophagy and apoptosis. Combined treatments showed the induction of HSP60 at 24 hpf and autophagic and apoptotic processes at 48 hpf. Treatments having low levels of HSPs expression showed high levels of apoptosis, and vice versa, clearly demonstrating the antagonistic effects of HSPs expression and apoptosis. Detection of fragmented DNA in apoptotic nuclei showed selective apoptosis, likely in extremely damaged cells. Our results indicate that the negative effects of Gd-exposure on P. lividus larval development and biomineralization will be mitigated by a near-future ocean warming, up to a thermotolerance threshold when negative synergistic effects were evident. Our data highlight the use of biomarkers as sensitive tools to detect environmental impacts as well as the need for a better understanding of the interactions between the multiple stressors faced by marine species in coastal environments.
海洋逐渐变暖以及海洋热浪对已经面临其他人为衍生危害（如沿海地区化学污染）的海洋生物构成重大威胁。在本研究中，我们调查了热应激和暴露于钆（Gd）（一种用于医学成像的造影剂，会进入水生环境）对海胆Paracentrotus lividus胚胎和幼体的综合影响。胚胎接受了六种处理，涉及三种温度（18°C、21°C、24°C）和两种钆浓度（对照：0 μM；处理组：20 μM）。关于发育进程，温度升高加速了发育并促使幼体阶段的达成，而在对照温度（18°C）下暴露于钆的胚胎在受精后24小时（hpf）时发育普遍延迟，在48 hpf时出现发育迟缓效应和骨骼生长受损。接近未来预测的温度升高（+3°C，21°C）降低了钆对发育的负面影响，异常百分比降低且骨骼生长得到改善。在当前海洋热浪条件下的极端升温（+6°C，24°C）与钆处理相结合，与21°C + 钆处理相比，导致达到晚期幼体阶段的胚胎比例更低。在分子水平上，蛋白质印迹分析表明钆是诱导热休克蛋白（HSP60、HSP70）表达的主要驱动因素。在48 hpf时，温度升高是激活额外细胞应激反应策略（如自噬和凋亡）的主要驱动因素。联合处理在24 hpf时显示出HSP60的诱导，在48 hpf时显示出自噬和凋亡过程。热休克蛋白表达水平低的处理显示出高水平的凋亡，反之亦然，清楚地表明了热休克蛋白表达与凋亡的拮抗作用。在凋亡细胞核中检测到的碎片化DNA显示出选择性凋亡，可能发生在极度受损的细胞中。我们的结果表明，未来海洋变暖将减轻暴露于钆对Paracentrotus lividus幼体发育和生物矿化的负面影响，直至出现负面协同效应的耐热阈值。我们的数据强调了使用生物标志物作为检测环境影响的敏感工具，以及更好地理解沿海环境中海洋物种面临的多种应激源之间相互作用的必要性。
