Can the integration of multiple biomarkers and sediment geochemistry aid solving the complexity of sediment risk assessment?: a case study with a benthic fish

Surveying toxicity of complex geochemical media as aquatic sediments often yields results that are either difficult to interpret or even contradictory to acknowledged theory. Multi-level biomarkers were investigated in a benthic fish exposed to estuarine sediments through laboratory and in situ bioassays, to evaluate their employment either in ecological risk assessment or in more mechanistic approaches to assess sediment-bound toxicity. Biomarkers reflecting lesions (such as genotoxicity or histopathology), regardless of their low or absent specificity to contaminants, are efficient in segregating exposure to contaminated from uncontaminated sediments even when classical biomarkers like CYP1A and metallothionein induction are inconclusive. Conversely, proteomics and gene transcription analyses provided information on the mechanics of toxicity and aided explaining response variation as a function of metabolic imbalance and impairment of defences against insult. In situ bioassays, although less expedite and more affected by confounding factors, produced data better correlated to overall sediment contamination.info:eu-repo/semantics/publishedVersio

Synthesis and evaluation of tumor cell growth inhibition of Methyl 3-Amino-6-[(hetero)arylethynyl]thieno[3,2-b]pyridine-2-carboxylates: structure-activity relationships, effects on the cell cycle and apoptosis

The methyl 3-amino-6-bromothieno[3,2-b]pyridine-2-carboxylate, recently reported by some of us, was reacted in Sonogashira couplings with several (hetero)arylacetylenes. The growth inhibitory activity of the novel methyl 3-amino-6-[(hetero)arylethynyl]thieno[3,2-b]pyridine-2-carboxylates obtained was evaluated on three human tumor cell lines (MCF-7, NCI-H460, A375-C5). The para-methoxyphenyl and the ortho and para-aminophenyl derivatives were the most promising compounds, and their effects were further studied regarding alterations in the normal cell cycle distribution and induction of apoptosis in the NCI-H460 cell line. All three compounds altered cell cycle distribution and the ortho-aminophenyl derivative was further shown to induce apoptosis in the same cell line.Associate Laboratory of the Portuguese Ministry of Science, Technology and Higher EducationFundação para a Ciência e a Tecnologia (FCT) - (Bruker Avance III 400) REDE/1517/RMN/2005, PTDC/QUI-QUI/111060/2009, SFRH/BD/29274/2006, SFRH/BPD/29112/2006European Social Fund

Estuarine ecological risk based on hepatic histopathological indices from laboratory and in situ tested fish

Juvenile Senegalese soles were exposed through 28-day laboratory and field (in situ) bioassays to sediments from three sites of the Sado estuary (W Portugal): a reference and two contaminated by metallic and organic contaminants. Fish were surveyed for ten hepatic histopathological alterations divided by four distinct reaction patterns and integrated through the estimation of individual histopathological condition indices. Fish exposed to contaminated sediments sustained more damage, with especial respect to regressive changes like necrosis. However, differences were observed between laboratory- and fieldexposed animals, with the latest, for instance, exhibiting more pronounced fatty degeneration and hepatocellular eosinophilic alteration. Also, some lesions in fish exposed to the reference sediment indicate that in both assays unaccounted variables produced experimental background noise, such as hyaline degeneration in laboratory-exposed fish. Still, the field assays yielded results that were found to better reflect the overall levels of contaminants and physico-chemical characteristics of the tested sediments.info:eu-repo/semantics/publishedVersio

Evaluation of the potential of the common cockle (cerastoderma edule l.) for the ecological risk assessment of estuarine sediments: Bioaccumulation and biomarkers

Common cockles (Cerastoderma edule, L. 1758, Bivalvia: Cardiidae) were subjected to a laboratory assay with sediments collected from distinct sites of the Sado Estuary (Portugal). Cockles were obtained from a mariculture site of the Sado Estuary and exposed through 28-day, semi-static, assays to sediments collected from three sites of the estuary. Sediments from these sites revealed different physico-chemical properties and levels of metals and organic contaminants, ranging from unimpacted (the reference site) to moderately impacted, when compared to available sediment quality guidelines. Cockles were surveyed for bioaccumulation of trace elements (Ni, Cu, Zn, As, Cd and Pb) and organic contaminants (PAHs, PCBs and DDTs). Two sets of potential biomarkers were employed to assess toxicity: whole-body metallothionein (MT) induction and digestive gland histopathology. The bioaccumulation factor and the biota-to-soil accumulation factor were estimated as ecological indices of exposure to metals and organic compounds. From the results it is inferred that C. edule responds to sediment-bound contamination and might, therefore, be suitable for biomonitoring. The species was found capable to regulate and eliminate both types of contaminants. Still, the sediment contamination levels do not account for all the variation in bioaccumulation and MT levels, which may result from the moderate metal concentrations found in sediments, the species’ intrinsic resistance to pollution and from yet unexplained xenobiotic interaction effects.info:eu-repo/semantics/publishedVersio

Produtividade do fósforo em Eucalyptus globulus

Congresso Florestal Nacional: a floresta e as gentes - Actas das ComunicaçõesO objectivo deste trabalho foi estudar a produtividade do fósforo (aumento de biomassa por unidade de fósforo na planta e por unidade de tempo, PP) em Eucalyptus globulus. A metodologia utilizada foi desenvolvida por Ingestad & Lund (1979), na qual as relações nutrição/crescimento são estudadas em condições de nutrição e crescimento em equilíbrio dinâmico, ou seja, com concentrações internas de nutrientes constantes e taxa de crescimento relativo constante. As aplicações deste método são inúmeras, desde uma melhor utilização de fertilizantes em viveiro até à compreensão do comportamento das plantas e do crescimento em condições naturais, em termos fisiológicos. O estudo incluiu três clones e um lote seminal, que foi utilizado como controlo, aos quais foram aplicados 3 níveis de nutrição, um óptimo (OP, com livre acesso de nutrientes) e dois sub-óptimos de nutrição de fósforo (PA e PB, com taxas de adição relativa de fósforo de 4 e 2%, respectivamente). Determinaram-se os valores da taxa máxima de crescimento relativo (RGmax), da concentração óptima de fósforo (conteúdo mínimo de fósforo na planta necessário para alcançar a taxa máxima de crescimento relativo, Popt) e da produtividade do fósforo (PP). Observaram-se diferenças significativas na PP entre o clone MP11 e o lote seminal. O clone MP11 foi o que apresentou a maior PP, mas com a mais baixa RGmax, embora não significativamente diferente dos outros clones ou lote seminal (4.58 - 7.08 % dia-1). Os valores obtidos para a PP (14.1 - 29.18 g (PS) g-1 (P) dia-1) estão em consonância com outros estudos

Genotoxic damage in Solea senegalensis exposed to sediments from the Sado Estuary (Portugal): effects of metallic and organic contaminants

Juvenile Solea senegalensis (Senegalese sole) were exposed to freshly collected sediments from three sites of the Sado Estuary (West-Portuguese coast) in 28-day laboratory assays in order to assess the ecological risk from sediment contaminants, by measuring two genotoxicity biomarkers in peripheral blood: the percentage of Erythrocyte Nuclear Abnormalities (ENA) by use of an adaptation of the micronucleus test, and the percentage of DNA strand-breakage (DNA-SB) with the Comet assay. Sediments were surveyed for metallic (Cr, Ni, Cu, Zn, As, Cd and Pb) and organic (PAHs (polycyclic aromatic hydrocarbons), PCBs (polychlorinated biphenyls) and DDTs (dichloro-diphenyl-trichloroethane)) contaminants. Sediments from site A (farthest from hotspots of contamination) were found to be the least contaminated and weaker inducers of genotoxic damage, whereas sediments from sites B (urban influence) and C (affected by industrial effluents and agricultural runoffs) were responsible for a very significant increase in both ENA and DNA-SB, site B being most contaminated with metals and site C mainly with organic pollutants, especially PAHs and PCBs . Analysis of genotoxic effects showed a strong correlation between the concentrations of PAHs and PCBs and both biomarkers at sampling times T14 and T28, while the amounts of Cu, As, Cd and Pb were less strongly correlated, and at T28 only, with ENA and DNA-SB. These results show that organic contaminants in sediment are stronger and faster acting genotoxic stressors. The results also suggest that metals may have an inhibitory effect on genotoxicity when interacting with organic contaminants, at least during early exposure. ENA and DNA-SB do not show a linear relationship, but a strong correlation exists between the overall increase in genotoxicity caused by exposure to sediment, confirming that they are different, and possibly non-linked effects that respond similarly to exposure. Although the Comet assay showed enhanced sensitivity, the two analyses are complementary and suitable for the biomonitoring of sediment contaminants in a benthic species like S. senegalensis.info:eu-repo/semantics/publishedVersio

Histological biomarkers in liver and gills of juvenile Solea senegalensis exposed

Young juvenile Solea senegalensis were exposed to three sediments with distinct contamination profiles collected from a Portuguese estuary subjected to anthropogenic sources of contamination (the Sado estuary, western Portugal). Sedimentswere surveyed formetals (cadmium, chromium, copper, nickel, lead and zinc), ametalloid (arsenic) and organic contaminants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls and a pesticide, dichloro-diphenyl-trichloroethane plus itsmetabolites), aswell as total organic matter, redox potential and particle fine fraction. The fish were exposed to freshly collected sediments in a 28-day laboratorial assay and collected for histological analyses at days 0 (T0), 14 (T14) and 28 (T28). Individual weighted histopathological indices were obtained, based on presence/absence data of eight and nine liver and gill pathologies, respectively, and on their biological significance. Although livers sustained more severe lesions, the sediments essentially contaminated by organic substances caused more damage to both organs than the sediments contaminated by both metallic and organic contaminants, suggesting a possible synergistic effect. Correlation analyses showed that some alterations are linked, forming distinctive histopathological patterns that are in accordance with the severity of lesions and sediment characteristics. The presence of large eosinophilic bodies in liver and degeneration of mucous cells in gills (a first-time described alteration)were some of the most noticeable alterations observed and were related to sediment organic contaminants. Body size has been found to be negatively correlated with histopathological damage in livers following longer term exposures. It is concluded that histopathological indices provide reliable and discriminatory data even when biomonitoring as complex media as natural sediments. It is also concluded that the effects of contamination may result not only from toxicant concentrations but also from their interactions, relative potency and sediment characteristics that ultimately determine bioavailability.peerreviewe

Biochemical endpoints on juvenile Solea senegalensis exposed

Juvenile Solea senegalensis were exposed to fresh sediments from three stations of the Sado estuary (Portugal) in 28-day laboratory assays. Sediments revealed distinct levels of total organic matter, fine fraction, redox potential, trace elements (arsenic, cadmium, chromium, copper, nickel, lead and zinc) and organic contaminants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls and a pesticide: dichloro diphenyl trichloroethane). Organisms were surveyed for contaminant bioaccumulation and induction of two hepatic biochemical biomarkers: metallothionein (MT) and cytochrome P450 (CYP1A), as potential indicators of exposure to metallic and organic contaminants, respectively. Using an integrative approach it was established that, although bioaccumulation is in general accordance with sediment contamination, lethality and biomarker responses are not linearly dependent of the cumulative concentrations of sediment contaminants but rather of their bioavailability and synergistic effects in organisms. It is concluded that metals and organic contaminants modulate both MT and CYP1A induction and it is suggested that reactive oxygen species may be the link between responses and effects of toxicity.peerreviewe

A description of chloride cell and kidney tubule alterations in the flatfish Solea senegalensis exposed to moderately contaminated sediments from the Sado estuary (Portugal)

The effects of sediment-bound contaminants on kidney and gill chloride cells were surveyed in juvenile Solea senegalensis exposed to fresh sediments collected from three distinct sites of the Sado Estuary (Portugal) in a 28-day laboratorial assay. Sediments were analyzed for metallic contaminants, polycyclic aromatic hydrocarbons and organochlorines as well as for total organic matter, redox potential and fine fraction. The potential for causing adverse biological effects of each surveyed sediment was assessed by comparison of contaminant levels to available guidelines for coastal sediments, namely the Threshold Effects Level (TEL) and the Probable Effects Level (PEL). The Sediment Quality Guideline Quotient indices (SQGQ) were calculated to compare the overall contamination levels of the three stations. A qualitative approach was employed to analyze the histo/cytopathological traits in gill chloride cells and body kidney of fish exposed to each tested sediment for 0, 14 and 28 days. The results showed that sediment contamination can be considered low to moderate and that the least contaminated sediment (from a reference site, with the lowest SQGQ) caused lesser changes in the surveyed organs. However, the most contaminated sediment (by both metallic and organic xenobiotics, with highest SQGQ) was neither responsible for the highest mortality nor for the most pronounced lesions. Exposure to the sediment presenting an intermediate SQGQ, essentially contaminated by organic compounds, caused the highest mortality (48%) and the most severe damage to kidneys, up to full renal necrosis. Chloride cell alterations were similar in fish exposed to the two most contaminated sediments and consisted of a pronounced cellular hypertrophy, likely involving fluid retention and loss of mitochondria. It can be concluded that sediment contamination considered to be low or moderate may be responsible for severe injury to cells and parenchyma involved in the maintenance of osmotic balance, contributing for the high mortality levels observed. The results suggest that sediment-bound organic contaminants such as PAHs (polycyclic aromatic hydrocarbons) and PCBs (polychlorinated biphenyls) may be very toxic to the analyzed organs, especially the kidney, even when present in lowrisk concentrations.info:eu-repo/semantics/publishedVersio

Assessment of the genotoxic potential of contaminated estuarine sediments in fish peripheral blood: laboratory versus in situ studies

Juvenile Senegalese soles (Solea senegalensis) were exposed to estuarine sediments through 28-day laboratory and in situ (field) bioassays. The sediments, collected from three distinct sites (a reference plus two contaminated) of the Sado Estuary (W Portugal) were characterized for total organic matter, redox potential, fine fraction and for the levels of metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorines, namely polychlorinated biphenyls (PCBs) and dichloro diphenyl tricholoethane plus its main metabolites (DDTs). Genotoxicity was determined in whole peripheral blood by the single-cell gel electrophoresis (SCGE or ‘‘comet’’) assay and by scoring erythrocytic nuclear abnormalities (ENA). Analysis was complemented with the determination of lipid peroxidation in blood plasma by the thiobarbituric acid reactive substances (TBARS) protocol and cell type sorting. The results showed that exposure to contaminated sediments induced DNA fragmentation and clastogenesis. Still, laboratory exposure to the most contaminated sediment revealed a possible antagonistic effect between metallic and organic contaminants that might have been enhanced by increased bioavailability. The laboratory assay caused a more pronounced increase in ENA whereas a very significant increase in DNA fragmentation was observed in field-tested fish exposed to the reference sediment, which is likely linked to increased lipid peroxidation that probably occurred due to impaired access to food. Influence of natural pathogens was ruled out by unaltered leukocyte counts. The statistical integration of data correlated lipid peroxidation with biological variables such as fish length and weight, whereas the genotoxicity biomarkers were more correlated to sediment contamination. It was demonstrated that laboratory and field bioassays for the risk assessment of sediment contamination may yield different genotoxicity profiles although both provided results that are in overall accordance with sediment contamination levels. While field assays may provide more ecologically relevant data, the multiple environmental variables may produce sufficient background noise to mask the true effects of contamination.info:eu-repo/semantics/publishedVersio