Martins Inês, Goulart Joana, Martins Eva, Morales-Román Rosa, Marín Sergio, Riou Virginie, Colaço Ana, Bettencourt Raul
MARE - Marine and Environmental Sciences Centre, 9901-862 Horta, Portugal; IMAR - Department of Oceanography and Fisheries, University of Azores, 9901-862 Horta, Portugal.
MARE - Marine and Environmental Sciences Centre, 9901-862 Horta, Portugal; IMAR - Department of Oceanography and Fisheries, University of Azores, 9901-862 Horta, Portugal.
Aquat Toxicol. 2017 Dec;193:40-49. doi: 10.1016/j.aquatox.2017.10.004. Epub 2017 Oct 9.
Over the past years, several studies have been dedicated to understanding the physiological ability of the vent mussel Bathymodiolus azoricus to overcome the high metal concentrations present in their surrounding hydrothermal environment. Potential deep-sea mining activities at Azores Triple junction hydrothermal vent deposits would inevitably lead to the emergence of new fluid sources close to mussel beds, with consequent emission of high metal concentrations and potential resolubilization of Cu from minerals formed during the active phase of the vent field. Copper is an essential metal playing a key role in the activation of metalloenzymes and metalloproteins responsible for important cellular metabolic processes and tissue homeostasis. However, excessive intracellular amounts of reactive Cu ions may cause irreversible damages triggering possible cell apoptosis. In the present study, B. azoricus was exposed to increasing concentrations of Cu for 96h in conditions of temperature and hydrostatic pressure similar to those experienced at the Lucky Strike hydrothermal vent field. Specimens were kept in 1L flasks, exposed to four Cu concentrations: 0μg/L (control), 300, 800 and 1600μg/L and pressurized to 1750bar. We addressed the question of how increased Cu concentration would affect the function of antioxidant defense proteins and expression of antioxidant and immune-related genes in B. azoricus. Both antioxidant enzymatic activities and gene expression were examined in gills, mantle and digestive gland tissues of exposed vent mussels. Our study reveals that stressful short-term Cu exposure has a strong effect on molecular metabolism of the hydrothermal vent mussel, especially in gill tissue. Initially, both the stress caused by unpressurization or by Cu exposure was associated with high antioxidant enzyme activities and tissue-specific transcriptional up-regulation. However, mussels exposed to increased Cu concentrations showed both antioxidant and immune-related gene suppression. Under a mining activity scenario, the release of an excess of dissolved Cu to the vent environment may cause serious changes in cellular defense mechanisms of B. azoricus. This outcome, while adding to our knowledge of Cu toxicity, highlights the potentially deleterious impacts of mining activities on the physiology of deep-sea organisms.
在过去几年中，已有多项研究致力于了解亚速尔贻贝（Bathymodiolus azoricus）克服其周围热液环境中高金属浓度的生理能力。亚速尔群岛三联点热液喷口矿床潜在的深海采矿活动将不可避免地导致靠近贻贝床出现新的流体源，从而排放高浓度金属，并可能使喷口场活跃期形成的矿物质中的铜重新溶解。铜是一种必需金属，在激活负责重要细胞代谢过程和组织稳态的金属酶和金属蛋白方面发挥着关键作用。然而，细胞内过量的活性铜离子可能会造成不可逆转的损害，引发细胞凋亡。在本研究中，亚速尔贻贝在与幸运 Strike 热液喷口场相似的温度和静水压力条件下，暴露于浓度不断增加的铜中 96 小时。样本置于 1 升烧瓶中，暴露于四种铜浓度下：0μg/L（对照）、300、800 和 1600μg/L，并加压至 1750 巴。我们探讨了铜浓度增加如何影响亚速尔贻贝抗氧化防御蛋白的功能以及抗氧化和免疫相关基因的表达。对暴露后的喷口贻贝的鳃、外套膜和消化腺组织进行了抗氧化酶活性和基因表达检测。我们的研究表明，短期的应激性铜暴露对热液喷口贻贝的分子代谢有强烈影响，尤其是在鳃组织中。最初，减压或铜暴露引起的应激都与高抗氧化酶活性和组织特异性转录上调有关。然而，暴露于浓度增加的铜中的贻贝表现出抗氧化和免疫相关基因的抑制。在采矿活动的情况下，向喷口环境中释放过量的溶解铜可能会导致亚速尔贻贝细胞防御机制发生严重变化。这一结果在增加我们对铜毒性认识的同时，也凸显了采矿活动对深海生物生理的潜在有害影响。
