MARE - Marine and Environmental Sciences Centre, ESTM, Politécnico de Leiria, Portugal.
Associação Programa Tatô, Avenida Marginal 12 de Julho, Cidade de São Tomé, São Tomé e Príncipe, Portugal.
Environ Pollut. 2022 Jan 15;293:118490. doi: 10.1016/j.envpol.2021.118490. Epub 2021 Nov 12.
Metals are persistent worldwide being harmful for diverse organisms and having complex and combined effects with other contaminants in the environment. Sea turtles accumulate these contaminants being considered good bioindicator species for marine pollution. However, very little is known on how this is affecting these charismatic animals. São Tomé and Príncipe archipelago harbours important green sea turtle (Chelonia mydas) nesting and feeding grounds. The main goal of this study was to determine metal and metalloid accumulation in the blood of females C. mydas nesting in São Tomé Island, and evaluate the possible impacts of this contamination by addressing molecular stress responses. Gene expression analysis was performed in blood targeting genes involved in detoxification/sequestration and metal transport (mt, mtf and fer), and in antioxidant and oxidative stress responses (cat, sod, gr, tdx, txrd, selp and gclc). Micronuclei analysis in blood was also addressed as a biomarker of genotoxicity. Present results showed significant correlations between different gene expressions with the metals evaluated. The best GLM models and significant relationships were found for mt expression, for which 78% of the variability was attributed to metal levels (Al, Cu, Fe, Hg, Pb and Zn), followed by micronuclei count (65% - Cr, Cu, Fe, Hg, Mn and Zn), tdx expression (52% - Cd, Fe, Mn, Pb and Se), and cat expression (52% - As, Fe, Se and Cd x Hg). Overall, this study demonstrates that these green sea turtles are trying to adapt to the oxidative stress and damage produced by metals through the increased expression of antioxidants and other protectors, which raises concerns about the impacts on these endangered organisms' fitness. Furthermore, promising biomarker candidates associated to metal stress were identified in this species that may be used in future biomonitoring studies using C. mydas' blood, allowing for a temporal follow-up of the organisms.
金属在全球范围内具有持久性，对各种生物都有害，并与环境中的其他污染物产生复杂的综合影响。海龟会积累这些污染物，因此被认为是海洋污染的良好生物指标种。然而，对于这如何影响这些魅力动物，我们知之甚少。圣多美和普林西比群岛拥有重要的绿海龟（Chelonia mydas）筑巢和觅食地。本研究的主要目的是确定在圣多美岛筑巢的雌性绿海龟血液中的金属和类金属积累情况，并通过研究分子应激反应来评估这种污染的可能影响。在血液中进行了基因表达分析，针对参与解毒/隔离和金属转运的基因（mt、mtf 和 fer），以及抗氧化和氧化应激反应的基因（cat、sod、gr、tdx、txrd、selp 和 gclc）进行了分析。还研究了血液中的微核分析作为遗传毒性的生物标志物。目前的结果表明，不同基因表达与评估的金属之间存在显著相关性。对于 mt 表达，发现了最佳的 GLM 模型和显著关系，其 78%的可变性归因于金属水平（Al、Cu、Fe、Hg、Pb 和 Zn），其次是微核计数（65% - Cr、Cu、Fe、Hg、Mn 和 Zn）、tdx 表达（52% - Cd、Fe、Mn、Pb 和 Se）和 cat 表达（52% - As、Fe、Se 和 Cd x Hg）。总体而言，这项研究表明，这些绿海龟正试图通过增加抗氧化剂和其他保护剂的表达来适应金属引起的氧化应激和损伤，这引起了人们对这些濒危生物适应能力的担忧。此外，在该物种中确定了与金属应激相关的有前途的生物标志物候选物，这些候选物可用于未来使用 C. mydas 血液进行的生物监测研究，从而可以对生物体进行时间跟踪。
