Applying quantitative and semi-quantitative histopathology to address the interaction between sediment-bound polycyclic aromatic hydrocarbons in fish gills.
Even though PAHs are considered priority marine pollutants, information on the interaction effects between these compounds is scarce, furthermore under ecologically-relevant circumstances. Semi-quantitative and quantitative histological analyses were enforced on the gills of the seabass (Dicentrarchus labrax), exposed to two model PAHs, single or combined, through a series of 28-day laboratory bioassays. Fish exposed to sediments contaminated with either PAH (250-800ngg(-1)), isolated or combined, exhibited most significant gill histopathological alterations after 28 days of exposure, as determined through weighted condition indices, especially in animals exposed to the potential carcinogen benzo[b]fluoranthene (B[b]F) and to mixtures of this compound with its lower, non-carcinogenic counterpart Phenanthrene (Phe). Negative correlations between interlamellar hyperplasia (the most remarkable alteration) and goblet cell counts suggest that fish exposed to sediments contaminated with B[b]F or mixed PAHs increased the thickness of epithelial cells as a response to insult, albeit compromising cell differentiation, to which is likely added impaired gas exchange and osmotic balance. In contrast, animals exposed to Phe increased the number of chloride and goblet cells relatively to control fish at early stages of exposure, suggesting then a more efficient protective mechanism. The results also showed that histopathological alterations in mixture-exposed animals do not match the expected additive effects. Overall, the findings indicate that chronic exposures to sediment-bound PAHs, under realistic scenarios, may induce lesions in gills that may imply significant hindering of basal metabolic/homeostatic pathways in marine fish whose interpretation may be hindered by complicated interaction effects and unknown factor involving, more that dose-response, time-dependent effects.
MARE - Marine and Environmental Sciences Centre, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal; UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal. Electronic address: marta.martins@fct.unl.pt.
Marta
M
Martins
MARE - Marine and Environmental Sciences Centre, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
José M
JM
Santos
MARE - Marine and Environmental Sciences Centre, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
Maria H
MH
Costa
MARE - Marine and Environmental Sciences Centre, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal; Unit of Molecular Toxicology, Institute of Environmental Medicine (IMM), Karolinska Institutet, Nobels väg 13, S-171 77 Stockholm, Sweden.
Pedro M
PM
Costa
D000818:Animals; D001492:Bass; D001681:Biological Assay; D002273:Carcinogens / Q000633:toxicity; D005449:Fluorenes / Q000633:toxicity; D019015:Geologic Sediments / Q000737:chemistry; D005880:Gills / Q000187:drug effects*; D010616:Phenanthrenes / Q000633:toxicity; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
D002273:Carcinogens; D005449:Fluorenes; D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; C031181:phenanthrene; C006703:benzo(b)fluoranthene
Benzo[b]fluoranthene; Dicentrarchus labrax; Goblet cells; Histopathological indices; Hyperplasia; Phenanthrene