Percorrer por autor "Abessa, Denis M. S."
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- Effects of mixtures of anticancer drugs in the benthic polychaete Nereis diversicolorPublication . Fonseca, Tainá; Abessa, Denis M. S.; Bebianno, Maria JoãoThe increasing consumption of anticancer drugs through single and/or combinatory chemotherapy worldwide raised concern regarding their toxicity burden in coastal zones. The toxicity of a mixture of three compounds involving the drugs cisplatin (CisPt), cyclophosphamide (CP) and tamoxifen (TAM) was determined on the marine polychaete Nereis diversicolor exposed to an increasing range of their concentrations, respectively: Mix A: 0.1 + 10 + 0.1 ng L-1; Mix B: 10 + 100 + 10 ng L-1; Mix C: 100 + 500 + 25 ng L-1; Mix D: 100 + 1000 + 100 ng L-1. Different endpoints were assessed, including disturbance in the burrowing behaviour, neurotoxicity (acetylcholinesterase - AChE activity), antioxidant enzymes (superoxide dismutase - SOD; catalase - CAT; selenium-dependent glutathione peroxidase - Se-GPx and total glutathione peroxidases T-GPx activities), biotransformation metabolism (glutathione-S-transferases - GST), lipid peroxidation (LPO) and genotoxicity (DNA damage). Biological effects of the mixtures of anticancer compounds on N. diversicolor were compared with previous studies about effects on the same biological model under single-drug exposure conducted with the same molecules. Regarding SOD activity, TAM showed an antagonist effect over CisPt and CP in mixtures C and D. In Mix D, there was a synergistic effect of TAM and CisPt that inhibited CAT activity and an additive interaction of CisPt and CP on the Phase II biotransformation enzyme. Drugs in Mix A also suppressed polychaetes' GST activity, although different from the respective single-drug responses, besides able to induce T-GPx activity, that was not sufficient to avoid oxidative damage and mid-grade DNA damage. Due to the absence of burrowing impairment in Mix A, mechanisms involved in neurotoxicity were other than the one driven by AChE alterations. At the intermediary concentrations (Mix B and C), only LPO occurred. Data from drugs individually may not predict the risks provided by mixtures.
- Metal bioaccumulation by the neotropical clam Anomalocardia flexuosa to estimate the quality of estuarine sedimentsPublication . Cruz, Ana C. F.; Pauly, Guacira F. E.; Araujo, Giuliana S.; Gusso-Choueri, Paloma; FONSECA, TAINÁ; Campos, Bruno G.; Santelli, Ricardo E.; Freire, A. S.; Braz, Bernardo F.; Bosco-Santos, Alice; Luiz-Silva, Wanilson; Machado, Wilson; Abessa, Denis M. S.This investigation evaluated the bioaccumulation potential of the tropical estuarine bivalve Anomalocardia flexuosa for trace metals. To this aim, chemical and sedimentological analyses and bioaccumulation tests were performed. The sediments were mainly composed by fine-sands and mud, with variable levels of organic matter and CaCO3. Muddy sediments from a depositional site (P2) presented the highest concentrations of metals, despite SEM/AVS not indicating bioavailability. Bioaccumulation factors showed high ratios for Cd, Ni, and Zn, while associations between the contents of mud, organic matter, CaCO3 and metals in sediments and tissues of A. flexuosa were indicated by a principal component analysis. The SEM/AVS was not effective to predict the bioavailability through dissolved metals. The results showed that contaminants were bioavailable, while the performed bioaccumulation test proved to be a reliable technique for assessing sediment contamination in estuarine regions. Moreover, A. flexuosa was considered an adequate test organism for bioaccumulation studies.
- Using an integrated approach to assess the sediment quality of an estuary from the semi-arid coast of BrazilPublication . Souza, Ivanildo Surini; Araujo, Giuliana Seraphim; Cruz, Ana Carolina Feitosa; Fonseca, Tainá; Camargo, Julia Beatriz Duarte Alves; Medeiros, Guilherme Fulgencio; Abessa, Denis M. S.The Jundiai-Potengi Estuary (JPE) on the semi-arid coast of Brazil is influenced by multiple sources of pollution. Sediment quality at 10 JPE sites was evaluated through an integrated approach. Rainy and dry seasons were considered. Collected sediments were analyzed for texture, metal, nitrogen, phosphorus concentrations, and toxicity to invertebrates. Geochemical and ecotoxicological data were integrated using qualitative approaches and multivariate techniques. We observed decreased sediment quality in both seasons, particularly in the mid estuary. In the dry season, the contamination-toxicity relationship was clearer, as hydrological conditions favor contaminant retention within the estuary. Rainy season conditions were found to be worse, since stormwater drainage from agricultural and urban areas carries the contamination into the estuary. Because of the contamination sources and dissolved and particle-bound metal transport, contamination and toxicity did not correlate as clearly in the rainy season. The results suggest that unmeasured contaminants are contributing to JPE sediment degradation. (C) 2016 Elsevier Ltd. All rights reserved.