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- Differential protein expression in mussels Mytilus galloprovincialis exposed to nano and ionic AgPublication . Gomes, Tânia; G. Pereira, Catarina; Cardoso, Cátia; Bebianno, Maria JoãoAg NPs are one of the most commonly used NPs in nanotechnology whose environmental impacts are to date unknown and the information about bioavailability, mechanisms of biological uptake and toxic implications in organisms is scarce. So, the main objective of this study was to investigate differences in protein expression profiles in gills and digestive gland of mussels Mytilus galloprovincialis exposed to Ag NPs and Ag(+) (10 μg L(-1)) for a period of 15 days. Protein expression profiles of exposed gills and digestive glands were compared to those of control mussels using two-dimensional electrophoresis to discriminate differentially expressed proteins. Different patterns of protein expression were obtained for exposed mussels, dependent not only on the different redox requirements of each tissue but also to the Ag form used. Unique sets of differentially expressed proteins were affected by each silver form in addition to proteins that were affected by both Ag NPs and Ag(+). Fifteen of these proteins were subsequently identified by MALDI-TOF-TOF and database search. Ag NPs affected similar cellular pathways as Ag(+), with common response mechanisms in cytoskeleton and cell structure (catchin, myosin heavy chain), stress response (heat shock protein 70), oxidative stress (glutathione s-transferase), transcriptional regulation (nuclear receptor subfamily 1G), adhesion and mobility (precollagen-P) and energy metabolism (ATP synthase F0 subunit 6 and NADH dehydrogenase subunit 2). Exposure to Ag NPs altered the expression of two proteins associated with stress response (major vault protein and ras partial) and one protein involved in cytoskeleton and cell structure (paramyosin), while exposure to Ag(+) had a strong influence in one protein related to stress response (putative c1q domain containing protein) and two proteins involved in cytoskeleton and cell structure (actin and α-tubulin). Protein identification showed that Ag NPs toxicity is mediated by oxidative stress-induced cell signalling cascades (including mitochondria and nucleus) that can lead to cell death. This toxicity represents the cumulative effect of Ag(+) released from the particles and other properties as particle size and surface reactivity. This study helped to unravel the molecular mechanisms that can be associated with Ag NPs toxicity; nevertheless, some additional studies are required to investigate the exact interaction between these NPs and cellular components.
- Genotoxicity in two bivalve species from a coastal lagoon in the south of PortugalPublication . Catarina Almeida, Ana; G. Pereira, Catarina; Gomes, Tânia; Cardoso, Cátia; Bebianno, Maria João; Cravo, AlexandraDNA damage was evaluated by comet assay in the haemolymph of two bivalve species Ruditapes decussatus and Mytilus galloprovincialis from the Ria Formosa lagoon (south Coast of Portugal). Clams and mussels were sampled from sites close to each other to determine interspecific responses to similar environmental conditions, considering also seasonal and gender differences. Coupled with genotoxic effect, another damage biomarker (lipid peroxidation) was analysed to verify if the conditions that instigate DNA damage can be related with injury to cell membranes. For both species, DNA damage was low, reflecting the low levels of genotoxic contaminants in the lagoon, and no interspecific differences were found. However, seasonal differences were established for both bivalve species, reflecting higher environmental stress in summer. Regarding gender susceptibility, only clams showed differences in percentage of Tail DNA, with females more sensitive to DNA damage than males. Additionally, results for clams point out that factors responsible for LPO may not be the same as those causing genotoxicity. This study demonstrated that DNA damage is a sensitive biomarker to discriminate spatial, temporal and gender differences, being an appropriate biomarker for genotoxicity evaluation even in places of low contamination, such as the Ria Formosa lagoon.
- Effects of silver nanoparticles exposure in the mussel Mytilus galloprovincialisPublication . Gomes, Tânia; Pereira, Catarina; Cardoso, Cátia; Serrão Sousa, Vânia; Ribau Teixeira, Margarida; Pinheiro, José P.; Bebianno, Maria JoãoSilver nanoparticles (Ag NPs) have emerged as one of the most commonly used NPs in a wide range of industrial and commercial applications. This has caused increasing concern about their fate in the environment as well as uptake and potential toxicity towards aquatic organisms. Accordingly, mussels Mytilus galloprovincialis were exposed to 10 μg L(-1) of Ag NPs and ionic silver (Ag+) for 15 days, and biomarkers of oxidative stress and metal accumulation were determined. Accumulation results show that both Ag NPs and Ag+ accumulated in both gills and digestive glands. Antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) were activated by Ag NPs and Ag+, showing different antioxidant patterns in both gills and digestive glands. Moreover, metallothionein was inducted in gills, directly related to Ag accumulation, while in the digestive glands only a small fraction of Ag seems to be associated with this protein. Lipid peroxidation was higher in gills exposed to Ag NPs, whereas in the digestive glands only Ag+ induced lipid peroxidation. Ag NPs and Ag+ cause oxidative stress with distinct modes of action and it's not clear if for Ag NPs the observed effects are attributed to free Ag+ ions associated with the nanoparticle effect.
- Tissue specific responses to cadmium-based quantum dots in the marine mussel Mytilus galloprovincialisPublication . Lopes Rocha, Thiago; Gomes, Tânia; Mestre, Nélia; Cardoso, Cátia; Bebianno, Maria JoãoIn recent years, Cd-based quantum dots (QDs) have generated interest from the life sciences community due to their potential applications in nanomedicine, biology and electronics. However, these engineered nanomaterials can be released into the marine environment, where their environmental health hazards remain unclear. This study investigated the tissue-specific responses related to alterations in the antioxidant defense system induced by CdTe QDs, in comparison with its dissolved counterpart, using the marine mussel Mytilus galloprovincialis. Mussels were exposed to CdTe QDs and dissolved Cd for 14 days at 10 μgCd L(-1) and biomarkers of oxidative stress [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (total, Se-independent and Se-dependent GPx) and glutathione-S-transferase (GST) activities] were analyzed along with Cd accumulation in the gills and digestive gland of mussels. Results show that both Cd forms changed mussels' antioxidant responses with distinct modes of action (MoA). There were tissue- and time-dependent differences in the biochemical responses to each Cd form, wherein QDs are more pro-oxidant when compared to dissolved Cd. The gills are the main tissue affected by QDs, with effects related to the increase of SOD, GST and GPx activities, while those of dissolved Cd was associated to the increase of CAT activity, Cd accumulation and exposure time. Digestive gland is a main tissue for accumulation of both Cd forms, but changes in antioxidant enzyme activities are smaller than in gills. A multivariate analysis revealed that the antioxidant patterns are tissue dependent, indicating nano-specific effects possibly associated to oxidative stress and changes in redox homeostasis.