Loading...
6 results
Search Results
Now showing 1 - 6 of 6
- Stress response markers in the blood of São Tomé green sea turtles (Chelonia mydas) and their relation with accumulated metal levelsPublication . Morão, Inês F.C.; Lemos, Marco F.L.; Félix, Rafael; Vieira, Sara; Barata, Carlos; Novais, Sara C.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. Sâo 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.
- Assessment of metal contamination levels and stress responses of endangered sea turtles of São Tomé and PrincipePublication . Morão, Inês F.; Novais, Sara C.; Vieira, Sara; Barata, Carlos; Piña, Benjamin; Lemos, Marco F.L.São Tomé Island harbors important sea turtle nesting and feeding sites. However, insufficient enforcement of environmental laws to avoid illegal take of nesting females and eggs, associated with a great lack of knowledge about how these species interact with their environment and how human activities impact their survival in the region, constitute significant challenges for sea turtle conservation. Through current local conservation projects, some information on genetics and nutrition of sea turtle populations is being unveiled but very little is known about how ocean pollution is impacting these turtles. The main objective of this study was to assess the metal concentrations accumulated by one species of S. Tomé sea turtles (Chelonia mydas) and infer about possible impacts of such contamination on their general stress responses and health status. More specifically, the final goal was to find correlations between metal concentrations and the expression of key genes involved in detoxification/sequestration and metal transport, antioxidant responses and oxidative stress, immunological responses, mitochondrial respiratory and energy production, among others, which could be indicative of these organisms health and future viability. To achieve these goals, nesting female turtles were sampled for blood, immediately after egg laying in their well-documented spawning sites in S. Tomé. Blood samples were withdrawn from the external jugular vein, a portion was stored in EDTA treated tubes at -20ºC until analysis of metal concentrations, and another portion was stored in RNAlater at -20°C until RNA extraction and gene expression analysis using quantitative real-time PCR (qPCR). Additionally, body mass and carapace length were also recorded, along with all information regarding egg spawning and its success. Results showed significant correlations between expression of some genes and metal contaminant levels, pinpointing some candidate genes to be used as biomarkers of interest for biomonitoring campaigns, which worrying function highlights the need for a close follow-up of these organisms. This study represents the first attempt to address pollutant levels and the biological impairments of such stressors in these turtle species nesting in S. Tomé which, given their classification as endangered species (IUCN red list), is of paramount importance to contribute for conservation measures and management.
- Assessment of metal contamination levels and stress responses of São Tomé and Principe sea turtlesPublication . Morão, Inês Filipa Cigarro; Lemos, Marco Filipe Loureiro; Novais, Sara CalçadaA ilha de São Tomé é uma importante área de nidificação e alimentação para quatro das sete espécies de tartarugas marinhas existentes no mundo. As tartarugas marinhas são classificadas como espécies ameaçadas (lista vermelha da IUCN) e sabe-se que as tartarugas marinhas estão sujeitas a muitas outras ameaças, nomeadamente a poluição oceânica. São poucos os estudos que têm sido desenvolvidos para avaliar como estas espécies interagem com o meio ambiente e como a poluição as afeta. O objetivo principal deste estudo foi avaliar as concentrações de metais acumulados na espécie Chelonia mydas e os impactos que estes contaminantes terão sobre as respostas de stress e inferir sobre o seu estado de saúde. De modo a alcançar estes objetivos, uma técnica menos invasiva foi efetuada, sendo recolhido sangue de fêmeas nidificantes, durante a desova, em locais de desova bem documentados em São Tomé. Amostras de sangue foram retiradas do seio cervical dorsal e uma porção foi armazenada em tubos contendo EDTA a -20ºC até a análise das concentrações de metais, e outra parte foi armazenada em RNAlater a -20 ° C até extração de RNA e análise de expressão genética usando PCR quantitativo em tempo real (qPCR). Também foram preparados esfregaços com o sangue das tartarugas e os danos no ADN foram avaliados através da observação de micronúcleos ao microscópio. Os resultados demostraram correlações significativas entre a expressão de alguns genes e os níveis de metais contaminantes, apontando alguns genes candidatos para serem usados como biomarcadores de interesse. Este estudo representa o primeiro esforço de abordar os níveis de poluentes e os danos biológicos de tais contaminantes nesta espécie de tartaruga que desova em São Tomé, contribuindo com informação relevante para ser usada em programas de biomonitorização para a conservação desta espécies ameaçadas.
- Exposure to the insecticide sulfoxaflor affects behaviour and biomarkers responses of Carcinus maenas (Crustacea: Decapoda)Publication . Damasceno, Jadilson M.; Rato, Lénia D.; Simões, Tiago; Morão, Inês F. C.; Meireles, Gabriela; Novais, Sara C.; Lemos, Marco F.L.Sulfoxaflor is an insecticide belonging to the recent sulfoximine class, acting as a nicotinic acetylcholine receptor (nAChRs) agonist. There are few studies regarding sulfoxaflor’s toxicity to non-target organisms. The present study aimed to investigate the acute and sub-lethal effects of sulfoxaflor on Carcinus maenas by addressing survival, behaviour (feed intake and motricity), and neuromuscular, detoxification and oxidative stress, and energy metabolism biomarkers. Adult male green crabs were exposed to sulfoxaflor for 96 h and an LC50 of 2.88 mg L1 was estimated. All biomarker endpoints were sampled after three (T3) and seven (T7) days of exposure and behavioural endpoints were addressed at T3 and day six (T6). Sulfoxaflor affected the feed intake and motricity of C. maenas at T6. From the integrated analysis of endpoints, with the increase in concentrations of sulfoxaflor, after seven days, one can notice a lower detoxification capacity (lower GST), higher LPO levels and effects on behaviour (higher motricity effects and lower feed intake). This integrated approach proved to be valuable in understanding the negative impacts of sulfoxaflor on green crabs, while contributing to the knowledge of this pesticide toxicity to non-target coastal invertebrates.
- Correlation between trace element concentrations in the blood of female hawksbill (Eretmochelys imbricata) and egg quality in nesting populations of São Tomé IslandPublication . Morão, Inês; Simões, Tiago; Busom Casado, Roger; Vieira, Sara; Ferreira-Airaud, Betânia; Caliani, Ilaria; Di Noi, Agata; Casini, Silvia; Fossi, Maria C.; Lemos, Marco F.L.; Novais, Sara C.Metals and metalloids can pose a significant threat to sea turtles, as these contaminants tend to accumulate in their bodies over time, due to their long lifespans and varied feeding habits. São Tomé and Príncipe's archipelago hosts the last remaining rookery for hawksbill sea turtles (Eretmochelys imbricata) in the region. The study aimed to determine the levels of metals and metalloids accumulated by this population and to investigate their possible genotoxicity in nesting females' blood as well as potential effects on their eggs in terms of morphometric characteristics and the quality of their lipidic reserves, essential for embryo development. Higher levels of Hg were found to be correlated with increased “lobed-shaped nuclei” in erythrocytic count, suggesting genotoxicity effects in this population. Higher levels of Se were correlated with thicker and heavier eggshells, while Pb levels were associated with the reduction of the egg's diameter. Metal contamination in females' blood significantly affected yolk polar fatty acids. Significant negative correlations were found between general metal contamination (PLI) and saturated fatty acids (SFA), while positive correlations were observed for essential omega-6 fatty acids (n6), mostly influenced by Cu, Fe, and Hg concentrations. This suggests that these omega-6 fatty acids are being synthesized from SFA, potentially indicating stress response by metal exposure. The present results point to some potential alterations in the normal embryonic development of these turtle eggs, influenced by metal contamination, which should raise some concerns about the future of this critically endangered species and call for additional conservation efforts in the region.
- Discriminative influence of persistent organic pollutants on nesting green sea turtles through genotoxicity, oxidative stress and reproductive related markersPublication . Morão, Inês; Muñoz-Arnanz, Juan; Simões, Tiago; Bartalini, Alice; Vieira, Sara; Ferreira-Airaud, Betânia; Caliani, Ilaria; Noi, Agata Di; Casini, Silvia; Fossi, Maria Cristina; Jiménez, Begoña; Lemos, Marco; Novais, SaraPersistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochloride pesticides (OCPs) affect biodiversity by bioaccumulating through food webs, impacting marine organisms like endangered sea turtles. This study represents the first evaluation of these contaminants in sea turtles nesting in São Tomé and Príncipe. The main goal was to evaluate PCBs, PBDEs and OCPs levels in sea turtles' blood and investigate their potential effects on erythrocytes’ nuclear abnormalities (ENAs) and oxidative stress and reproduction-related gene expression. The relative mean abundance for contaminants was ΣPCBs > ΣOCPs > ΣPBDEs. Contaminants such as PCB-28, PCB-138, PCB-153, PCB-180 and p,p’-DDE were associated with ENAs, suggesting potential genetic instability and cellular disruption. PCB-126, PBDE-100, and o,p’-DDD correlated with antioxidant and detoxification genes (glrx3, gst, txnip, txnrd2, and gclc), suggesting oxidative stress responses. The reproduction-related gene est17 was correlated with α and β-HCH, potentially affecting ovary development. Correlations between ace2 and various PCBs, PBDEs, and o,p'-DDD suggest disruptions in follicular development and egg transport. Embryo development genes (hoxA1 and tuba1) were associated with PBDE-154, PBDE100 and o,p’-DDD, suggesting possible embryonic alterations. These findings highlight the impacts of POPs on nesting female green turtles in São Tomé, threatening this endangered population.