69 research outputs found
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
- …