Usefulness of Bioindicators and Biomarkers in Pollution Biomonitoring

We have different possibilities and tools to assess the impact of pollution on marine ecosystems. The ecotoxicological approaches are based on the use of biomonitors and biomarkers. They aim to study the effect of toxic chemicals on the biological organisms especially at the population, community and ecosystem levels. The ultimate goal of ecotoxicology is to be able to predict the effects of pollution so that the most efficient and effective action to prevent or remediate any detrimental effect.In order to assess the impact of anthropogenic activities on the aquatic ecosystem and to insure compliance with regulation or guidelines, we use biomonitoring. This kind of approach is based on the use of biological responses in order to assess anthropogenic changes in the environment. Biomonitoring involves the use of indicator species such as filter feeding mollusk bivalves. These organisms tend to accumulate pollutants in their tissues without showing any apparent detrimental effect. Moreover, they could reflect the real bio available fraction of the pollutant. In order to have an early warning system predicting the pollution effects even at low levels, biomarkers were extensively studied. Some of them were validated in both field and in vivo conditions.In the present paper, the usefulness of bioindicators and biomarkers in pollution monitoring are discussed. An overview of results from case studies dealing with in situ, in vivo and transplantation experiments is presented

Estrogenic Endocrine Disruptors and their Possible Deleterious Effects on Marine Organisms: Use of a Novel Monitoring Bioassay

Abstract: Estrogens are both natural and synthetic substances that mimic the effect of the female estrogenic hormone in the body and impart estrogenic activity. Human wastes, birth control pills and chemicals like detergents are a major source of estrogens in the environment. In waste water treatment plants, a major part of these estrogens are not removed after treatment and are released in the marine environment. They are suspected to interfere with the exposed aquatic species™ endocrine systems. In fact, they mimic the effect of the endogenous hormone and therefore can disrupt the endocrine systems of exposed species and the reproductive systems of aquatic fauna. To understand their environmental fate, the estrogenic activity was studied by using the Yeast Estrogenic Screening (YES) bioassay. This bioassay has been validated in the detection of a wide range of estrogenic receptor agonists. A reverse phase HPLC method was used to identify the nature of estrogenic components.We focused on two marine bivalves Ruditapes decussatus and Cerastoderma glaucum recognised bioindicator organisms useful in biomonitoring. Our work is based on in situ and in vivo studies. Different compartments were used: the effluents of a wastewater treatment plant, the sea water, the sediment and the clam Ruditapes decussatus. Some observed histological effects showing hermaphroditic cases and parasites in the cockle Cerastoderma glaucum are also discussed in this paper

Utilisation et mise au point au niveau moléculaire de biomarqueurs pour étudier la répartition spatiale de la contamination au voisinage d une source de pollution

La répartition spatiale du Cd et son impact écotoxicologique ont été évalués à l'aide des biomarqueurs métallothionéines (MT), malonedialdéhyde (MDA) et acétylcholinéstérase (AChE). Les résultats montrent que la contamination migre vers le sud par les courants de direction nordsud. Les teneurs en biomarqueurs reflètent l'état alarmant de cet écosystème. La palourde Rudifapes decussatus et la coque Cerastoderma glaucum ont pu développer des systèmes adaptatifs particuliers pour survivre dans de telles conditions. Deux séquences partielles d'ADNc MT ont été clonées et utilisées comme sonde pour mesurer le taux d'ARN MT. L'analyse en dot blot a confirmé l'induction de l'expression du gène MT dans les branchies des animaux contaminés. Une différentiation génétique entre différentes populations de C. glaucum (Méditerranée, Atlantique, Mer du Nord) et C. edule (Atlantique et Mer du Nord) a été réalisée à l'aide des séquences 28S, ITSI et COI.The spatial distribution of Cd was studied and its toxicological impact was evaluated using metallothionein (MT), malonedialdehyde (MDA) and acetylcholinesterase (AChE) as biomarkers. Results showed that Cd contamination migrates southward the polluted site by the NS currents. The biomarkers concentrations reflect the alarming state of this ecosystem. The clam Ruditapes decussatus and the cockle Cerastoderma glaucum may have settled up sorne peculiar adaptive strategies to survive in such conditions. Two partial MT cDNAs were cloned from R. decussatus and C. glaucum and used as probes to quantify the MT mRNA levels. Dot blot analysis confirmed the induction of MT gene expression in gills of the contaminated animaIs. A genetic discrimination between different populations of C. glaucum from the Mediterranean sea, Atlantic and the North sea, and C. edule from Atlantic and the North sea were performed using the 28S, ITSI and COI sequences.LE MANS-BU Sciences (721812109) / SudocSudocFranceF

Effets de la contamination in situ (golfe de Gabès) par le cadmium sur la synthèse des métallothionéines et sur le potentiel reproducteur de la palourde Ruditapes decussatus

Notre étude a porté sur la bioaccumulation in situ du Cd chez la palourde, et ses effets sur leur potentiel reproducteur, dans deux sites du golfe de Gabès: " El Hofra " fortement contaminé et " Bordj d'Ungha " moins impacté. Les palourdes d'El Hofra présentent les concentrations en Cd les plus fortes, avec des fluctuations saisonnières reflétant le phénomène de dilution biologique, essentiellement lié au stade de développement des gonades. Les concentrations en Cd et en métallothionéines (MTs) sont plus élevées dans la glande digestive que dans les branchies. Elles y sont significativement corrélées pour les palourdes des deux sexes d'El Hofra, et pour les mâles de Bordj d'Ungha. L'étude des cycles reproducteurs a révélé un retard de la maturité des gamètes chez les femelles du site contaminé. Cd pourrait perturber l'activité des gonades en créant un déséquilibre hormonal. Le décalage avec la période de maturité des mâles pourrait influer sur le potentiel reproducteur de l'espèce.Our study related to the in situ bioaccumulation of Cd in the clam, and its effects on their reproductive potential, in two sites of the gulf of Gabès: "El Hofra" strongly contaminated and "Bordj d'Ungha" less impacted. The clams from El Hofra present the strongest Cd concentrations, with seasonal fluctuations reflecting the phenomenon of biological dilution, primarily related to the stage of development of gonads. The concentrations of Cd and metallothioneins (MTs) are higher in digestive gland than in the gills. They are significantly correlated in the digestive gland for the clams of the two sexes from El Hofra, and for the males from Bordj d'Ungha. The study of the reproductive cycles revealed a delay of the maturity of the gametes in the females of the contaminated site. Cd could disturb the activity of the gonads by creating an hormonal imbalance. The shift with the period of maturity of the males could influence the reproductive potential of this species.NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

A pilot study of genetic differentiation between two phenotypes of a Mediterranean population of the bivalve Cerastoderma glaucum and genetic discrimination with other Cerastoderma glaucum and Cerastoderma edule populations outside the Mediterranean

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Cytotoxicity and genotoxicity effects of arsenic trioxide on SQ20B human laryngeal carcinoma cells

International audienceThis study investigates the cytotoxicity and the genotoxicity induced by arsenic trioxide As2O3in human laryngeal SQ20B carcinoma cell line. SQ20B cells were exposed to graded concentrations of arsenic trioxide (2 and 5μM) for 48h. Comet assay and γ-H2AX foci formation were used for measuring DNA damages, flow cytometry was used to identify cell cycle alterations and apoptosis, while cell morphology was visualized using transmission electron microscopy. The results show a dose-dependent induction of DNA damages and double strand breaks, alterations in cell cycle and morphologic alterations of cells. These results prove that As2O3 is highly cytotoxic and genotoxic at the micromolar range ina human laryngeal carcinoma cell line

Virgibacillus salarius sp. nov., a novel halophilic bacterium isolated from a Saharan salt lake

A Gram-positive, endospore-forming, rod-shaped and moderately halophilic bacterium was isolated from a salt crust sample collected in Gharsa salt lake (Chott el Gharsa), Tunisia. The newly isolated bacterium designated SA-Vb1T was identified based on polyphasic taxonomy including genotypic, phenotypic and chemotaxonomic characterization. Strain SA-Vb1T was closely related to Virgibacillus marismortui and V. olivae with 16S rRNA gene sequence similarities of 99.7% and 99.4%, respectively. However, strain SA-Vb1T was distinguished from these two species on phenotypic characteristics and on the basis of DNA-DNA relatedness (29.4% and 5.1%, respectively). Genetic relationships between strain SA-Vb1T and the type species V. pantothenticus IAM 11061T and other type strains of the genus were 96-98% based on 16S rRNA gene and 18.3-22.3% based on DNA-DNA hybridization. Biochemical analysis resulted in determination of major fatty acids, iso-C15:0, anteiso-C15:0 and anteiso-C17:0 (33.3%, 29.2%, and 9.8%, respectively); phosphatidyl glycerol, diphosphatidyl glycerol, and phosphatidyl ethanolamine were the main polar lipids; and MK-7 the predominant menaquinone (~100%). The distinct characteristics demonstrated by these data show that strain SA-Vb1T represents properties of a novel species of the genus Virgibacillus. Accordingly, this isolate is proposed as Virgibacillus salarius sp. nov. The type strain is SA-Vb1T (=JCM 12946T =DSM 18441T)

Does a short-term exposure to cadmium chloride affects haemocyte parameters of the marine gastropod Haliotis tuberculata?

International audienceIn this study, a model based on primary cultured haemocytes from the gastropod mollusc Haliotis tuberculata was established to investigate the effects of cadmium chloride in vitro. Cells were exposed for 24 h to CdCl2 concentrations of 0, 1 and 100 μg ml−1. The effects of cadmium on haemocyte parameters were investigated using morphological, spectrophotometric and flow cytometry analysis. Results showed that cadmium has no significant effects on cell viability and phagocytotic activity under the tested conditions. However, haemocytes became more rounded after cadmium exposure, which could explain the significant decrease of cell area beginning at 1 μg ml−1 of CdCl2

Genotoxic effects of cadmium in human head and neck cell line SQ20B

International audienceAs cadmium may be involved in the etiology of head and neck cancers, we investigated in the present work, the cytotoxic and genotoxic effects of Cd on human larynx cells. SQ20B cells were exposed to 25 and 50 μM Cd for 48 and 72 h. Results showed a dose-dependent decrease in cell viability, especially after 48 h, associated with mitochondria alterations as showed by transmission electronic microscopy. Surprisingly, the flow cytometry shows that the cells treated with Cd have a normal proliferative cycle like the untreated cell especially in G1 or G2 phase of cell cycle. DNA damages were investigated by comet assay and immunofluorescence for gamma layer of the H2AX (g-H2AX) foci formation. Results show a strong induction of DNA double-strand breaks after Cd exposure. Overall, our results demonstrate the cytotoxicity and genotoxicity of Cd in human larynx cells and support the view that Cd could be an etiologic factor of head and neck cancers

Storage and reproductive strategy of the carpet-shell clam, Ruditapes decussatus in the Gulf of Gabès (Tunisia)

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