Marine pollution due to disused industrial activities is a major threat to ecosystems and human health, for example through the effects of re-suspension of toxic substances that are present in contaminated sediments. Here, we examined the effects of different re-suspension patterns of polluted sediments from the site of national interest Bagnoli-Coroglio, on the immune system of the sea urchin Paracentrotus lividus. An indoor experiment was set up exposing sea urchins for 34 days to such sediments and evaluating the effects of two patterns of water turbulence, mimicking natural storms at sea. One group of animals experienced an "aggregated" pattern of turbulence, consisting in two events, each lasting 2 days, separated by only 3 calm days, while a second group experienced two events of turbulence separated by 17 calm days (spaced pattern). At different times from the beginning of the experiment, coelomic fluid was collected from the animals and immune cells were examined for cell count and morphology, oxidative stress variables, and expression of genes involved in metal detoxification, stress response and inflammation. Our results highlighted that the aggregated pattern of turbulence was more noxious for sea urchins. Indeed, their immune system was altered, over the exposure time, as indicated by the increase of red amoebocytes number. Moreover, despite of an increase of the antioxidant power, animals from this group displayed a very significant ROS over-production at the end of the experiment. Conversely, animals in the spaced condition activated a different immune response, mainly having phagocytes as actors, and were able to partially recover from the received stress at the end of the experiment. No changes in the expression of genes related to antioxidant and anti-inflammatory responses were observed in both groups. By contrast, a down-regulation of various metallothioneins (4, 6, 7 and 8) in the group subjected to aggregated pattern was observed, while metallothionein 8 was up-regulated in the animals from the group exposed to the spaced pattern of turbulence. This work provides the first evidence of how sea urchins can respond to different re-suspension patterns of polluted sediments by modulating their immune system functions. The present data are relevant in relation to the possible environmental restoration of the study site, whose priorities include the assessment of the effects of marine pollution on local organisms, among which P. lividus represents a key benthic species.

中文翻译：

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海胆Paracentrotus lividus对高度污染的海洋沉积物的不同重悬浮模式的抗氧化和免疫反应。

废弃的工业活动造成的海洋污染是生态系统和人类健康的主要威胁，例如通过重新悬浮受污染沉积物中存在的有毒物质的影响。在这里，我们检查了来自国家利益地区Bagnoli-Coroglio的受污染沉积物的不同重悬方式对海胆Paracentrotus lividus免疫系统的影响。建立了一个室内实验，将海胆暴露在这种沉积物中34天，并评估了模仿海洋自然风暴的两种水湍流的影响。一组动物经历了一种“聚集的”湍流模式，包括两个事件，每个事件持续2天，仅相隔3天平静的时间，而第二组经历了两次湍流事件，相隔17天平静的天（间隔模式）。从实验开始的不同时间，从动物身上收集腔积液，并检查免疫细胞的细胞计数和形态，氧化应激变量以及涉及金属排毒，应激反应和炎症的基因表达。我们的结果强调，湍流的聚集模式对海胆更有害。实际上，它们的免疫系统在暴露时间内发生了变化，如红色变形细胞数量的增加所表明的。此外，尽管抗氧化剂的能力有所提高，但该组动物在实验结束时仍表现出非常显着的ROS超量生产。相反，处于间隔状态的动物会激活不同的免疫反应，主要具有吞噬细胞的作用，并且在实验结束时能够部分地从承受的压力中恢复过来。两组均未观察到与抗氧化剂和抗炎反应相关的基因表达变化。相比之下，在经历聚集模式的组中观察到各种金属硫蛋白（4、6、7和8）的下调，而在暴露于间隔紊乱模式的组中的动物中金属硫蛋白8被上调。这项工作提供了第一个证据，证明海胆如何通过调节其免疫系统功能来应对受污染沉积物的不同重悬浮模式。目前的数据与研究地点可能的环境恢复相关，