Browsing by Author "Soares, Amadeu M.V.M."
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- Biochemical performance of native and introduced clam species living in sympatry: The role of elements accumulation and partitioningPublication . Velez, Cátia; Leandro, Sérgio; Figueira, Etelvina; Soares, Amadeu M.V.M.; Freitas, RosaThe present study reports metal and arsenic contamination in sediments, as well as element accumulation and partitioning in native (Ruditapes decussatus and Venerupis corrugata) and introduced (Ruditapes philippinarum) clam species living in sympatry at the Obidos lagoon (Portugal). The biochemical performance and the human health risks derived from the consumption of these species are also discussed. The results obtained showed that R. decussatus was the most abundant species in all the sampling sites, revealing that the introduced clam has not yet supplanted the native species. The concentration of elements was higher in areas with higher Total Organic Matter (TOM) and fines content, being Chromium (Cr), Copper (Cu) and Lead (Pb) the most abundant metals. Clams from these areas showed the highest concentration of elements but the lowest bioaccumulation levels. Furthermore, except for As, higher concentration of elements was found in clams insoluble fraction, the less toxic fraction to the organisms. Due to the low contamination levels and because elements, except As, were mainly allocated to the insoluble fraction, clams presented similar biochemical parameters among distinct areas, with no significant oxidative stress induced. Furthermore, clams from the Obidos lagoon represent a low health risk to human consumption since, except for As, their contamination levels were below the maximum permissible limits defined by international organizations.
- Compounds altering fat storage in Daphnia magnaPublication . Jordão, Rita; Garreta, Elba; Campos, Bruno; Lemos, Marco; Soares, Amadeu M.V.M.; Tauler, Romà; Barata, CarlosThe analysis of lipid disruptive effects in invertebrates is limited by our poor knowledge of the lipid metabolic pathways. A recent study showed that tributyltin activated the ecdysteroid, juvenile hormone and retinoic X receptor signaling pathways, and disrupted the dynamics of neutral lipids in the crustacean Daphnia magna impairing the transfer of triacylglycerols to eggs and hence promoting their accumulation in post-spawning females. Tributyltin disruptive effects correlated with lower fitness for offspring and adults. The present study aims to addresses effects of existing compounds on storage lipids in post-spawning females and their health effects. D. magna individuals were exposed 12 chemicals that included vertebrate obesogens (tributyltin, triphenyltin, bisphenol A, nonylphenol, di-2-ethylhexyl phthalate), other contaminants known to affect arthropods (pyriproxyfen, fenarimol, methoprene, emamectin benzoate and fluoxetine), as well as the natural hormones methyl farnesoate and 20-hydroxyecdysone. Reproductive effects were also assessed. Quantitative changes in storage lipids accumulated in lipid droplets were studied using Nile red staining, which showed a close relationship with whole organism levels of triacylglycerols. Ten compounds altered storage lipids in a concentration related manner enhancing (tributyltin, bisphenol A, methyl farnesoate, pyriproxyfen and 20-hydroxyecdysone) or decreasing (nonylphenol, fenarimol, emamectin benzoate, methoprene and fluoxetine) their levels in post-spawning females. Eight compounds that altered lipid levels also had detrimental effects on growth and/or reproduction.
- Induction of multixenobiotic defense mechanisms in resistant Daphnia magna clones as a general cellular response to stressPublication . Jordão, Rita; Campos, Bruno; Lemos, Marco; Soares, Amadeu M.V.M.; Tauler, Romà; Barata, CarlosMultixenobiotic resistance mechanisms (MXR) were recently identified in Daphnia magna. Previous results characterized gene transcripts of genes encoding and efflux activities of four putative ABCB1 and ABCC transporters that were chemically induced but showed low specificity against model transporter substrates and inhibitors, thus preventing us from distinguishing between activities of different efflux transporter types. In this study we report on the specificity of induction of ABC transporters and of the stress protein hsp70 in clones selected to be genetically resistant to ABCB1 chemical substrates. Clones resistant to mitoxantrone, ivermectin and pentachlorophenol showed distinctive transcriptional responses of transporter protein coding genes and of putative transporter dye activities. Expression of hsp70 proteins also varied across resistant clones. Clones resistant to mitoxantrone and pentachlorophenol showed high constitutive levels of hsp70. Transcriptional levels of the abcb1 gene transporter and of putative dye transporter activity were also induced to a greater extent in the pentachlorophenol resistant clone. Observed higher dye transporter activities in individuals from clones resistant to mitoxantrone and ivermectin were unrelated with transcriptional levels of the studied four abcc and abcb1 transporter genes. These findings suggest that Abcb1 induction in D. magna may be a part of a general cellular stress response.
- The use of Cerastoderma glaucum as a sentinel and bioindicator species: Take-home messagePublication . Velez, Cátia; Pires, Adília; Sampaio, Leandro; Cardoso, Paulo; Moreira, Anthony; Leandro, Sérgio; Figueira, Etelvina; Soares, Amadeu M.V.M.tBivalves are frequently used to assess environmental contamination, and are often considered goodsentinel and/or bioindicator species. For that reason the bioaccumulation and toxicity induced by metalsand As in the cockle Cerastoderma glaucum, collected from areas with different contamination levelsalong the Óbidos lagoon (Portugal), were used to evaluate the use of this species as sentinel and/orbioindicator. The results showed that areas in the middle of the lagoon presented lower metals and Asconcentrations, lower total organic matter content and lower percentage of fine particles than areasin the Bom Sucesso arm. In all areas Cr, Pb and Cu were the most abundant elements, while Ni, As,Cd and Hg were less abundant. Results also showed a moderate correlation between total elementsconcentrations found in C. glaucum and in sediment, and thus caution should be taken when consideringthis species as a good sentinel species. The present study also revealed that, in general, C. glaucum fromareas in the middle of the lagoon accumulated higher concentrations of metals and As (Biota-SedimentAccumulation Factor >1) than cockles from the most polluted areas located in the Bom Sucesso arm.However, in all areas, the majority of metals (Cu, Cr, Pb) were found in cockles insoluble fraction whichmay explain low cellular damage and reduced oxidative stress responses observed. Therefore, our resultsmay further alert for caution when identifying C. glaucum as a good bioindicator species. Thus, our findingshighlight the fact that studies should be cautious when selecting species for environmental monitoring,since good sentinels or bioindicators in highly polluted systems may not act in the same way in lowor moderately contaminated areas. Furthermore, our study warns for the misclassification of cockles indifferent ecosystems.© 2015 Elsevier Ltd. All rights reserved.1. IntroductionCoastal systems have been constantly threatened by pollution,due to the increase of urbanization, agriculture and industrialactivities (Green-Ruiz and Páez-Osuna, 2001; Poulos et al., 2000).Considering this, it is well established that sediment act as a sink fora variety of contaminants, such as metals and metalloids (Buruaemet al., 2012; Hoffman et al., 2002), affecting benthic organisms(Dauvin, 2008). Environmental impact assessment studies haverelied on monitoring benthic community parameters (e.g. speciesrichness and abundance), measuring the concentrations of selected∗Corresponding author at: Departamento de Biologia & CESAM, Universi-dade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.Tel.: +351 234370782; fax: +351 234372587.E-mail