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Genotoxic damage in Solea senegalensis exposed to sediments from the Sado Estuary (Portugal): effects of metallic and organic contaminants
Publication . Costa, Pedro M.; Lobo, Jorge; Caeiro, Sandra; Martins, Martins; Ferreira, Ana M.; Caetano, Miguel; Vale, Carlos; DelValls, T. Ángel; Costa, Maria Helena
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.
Transcriptomic analyses in a benthic fish exposed to contaminated estuarine sediments through laboratory and in situ bioassays
Publication . Costa, Pedro M.; Miguel, Célia; Caeiro, Sandra; Lobo, Jorge; Martins, Marta; Ferreira, Ana M.; Caetano, Miguel
The transcription of contaminant responserelated genes was investigated in juvenile Senegalese soles
exposed to sediments from three distinct sites (a reference
plus two contaminated) of a Portuguese estuary (the Sado,
W Portugal) through simultaneous 28-day laboratory and in
situ bioassays. Transcription of cytochrome P450 1A
(CYP1A), metallothionein 1 (MT1), glutathione peroxidase
(GPx), catalase (CAT), caspase 3 (CASP3) and 90 kDa
heat-shock protein alpha (HSP90AA) was surveyed in the
liver by real-time PCR. CASP3 transcription analysis was
complemented by surveying apoptosis through the TUNEL
reaction. After 14 days of exposure, relative transcription
was either reduced or decreased in fish exposed to the contaminated sediments, revealing a disturbance stress
phase during which animals failed to respond to insult.
After 28 days of exposure all genes’ transcription responded to contamination but laboratory and in situ assays
depicted distinct patterns of regulation. Although sediments revealed a combination of organic and inorganic
toxicants, transcription of the CYP1A gene was consistently correlated to organic contaminants. Metallothionein
regulation was found correlated to metallic and organic
xenobiotic contamination in the laboratory and in situ,
respectively. The transcription of oxidative stress-related
genes can be a good indicator of general stress but caution
is mandatory when interpreting the results since regulation
may be influenced by multiple factors. As for MT1, HSP90
up-regulation has potential to be a good indicator for total
contamination, as well as the CASP3 gene, even though
hepatocyte apoptosis depicted values inconsistent with
sediment contamination, showing that programmed cell
death did not directly depend on caspase transcription
alone.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
POSI
Funding Award Number
19815