Bisphenol a (BPA) aggravate the adverse effect on physiological and biochemical response in freshwater mussel potomida littoralis.

Bisphenol A (BPA) is a chemical compound extensively employed in plastic manufacturing, and this pollutant has been detected in diverse aquatic organisms, notably bivalves. In order to comprehend the ecological and toxicological consequences of BPA Bisphenol A in these organisms, it is essential to examine the physiological and biochemical effects and identify areas where our understanding is lacking. This knowledge is crucial for determining the environn ental threat posed by bisphenol A and assisting decision-makers in establishing the appropriate priorities. This investigation aimed to assess the impact of BPA on the biochemical and physiological parameters of the freshwater mussel Potomida littoralis. In a laboratory setting, mussels were subjected to two different levels of BPA (20 and 100 µg/L) for a duration of 21 days. Filtration rate was calculated from the clearance of neutral red, fed to mussels at different BPA concentrations. The mussel's filtration rate capacity declined as BPA exposure intensified, potentially due to the mussel's attempt to close its valves and minimize BPA absorption, thus preventing cellular damage. In the digestive gland tissue, key antioxidant and detoxification defenses, including catalase (CAT) activity, glutathione-S-transferase (GST) activity, and levels of H2O2 and glutathione (GSH), were activated, particularly at the 100 µg/L BPA concentration. This activation helped protect against lipid damage at higher BPA concentrations. This study underscores the significance of preventing and regulating BPA release into the environment to avert detrimental consequences for aquatic ecosystems.

Developmental exposure to the A6-pesticide causes changes in tyrosine hydroxylase gene expression, neurochemistry, and locomotors behavior in larval zebrafish.

Purpose: In recent years, the increase in the biopesticides synthesis for alternative agricultural uses has required their impacts study. Among these compounds, several of them are known to exert endocrinedisrupting (EDs) effects causing deregulation of physiological functions affecting cell signaling pathways involved in neural cell differentiation leading to developmental neurotoxicity. The objective of our study was to determine the impact of the biopesticide A6 structurally related to estrogenic EDs on zebrafish larvae, to define its toxicity, the mechanisms responsible, and to monitor the locomotors activity at nanomolar concentrations (0. 0.5, 5 and 50 nM).Materials and methods: Using imaging analysis tools, immunohistochemistry, quantitative PCR, and an automated behavior recording system (Zebrabox) we were able to assess these effects.Results: We have shown through its blue fluorescence properties that it accumulates in different parts of the body such as the intestine, adipose tissue, muscles, yolk sac and head. A6 also disrupted swimming behavior by affecting the expression of tyrosine hydroxylase (TH) in dopaminergic neurons.Conclusions: In conclusion, our study provided a mechanistic understanding of the A6 neurotoxic effect which could be the result of its binding to the estrogen receptor.

Au-TiO2 nanoparticles exposure induced oxidative stress and neurotoxicity in rat.

CONTEXT: The Au-TiO2NPs have a wide range of applications and can easily enter the cells. Due to their properties, they can cause toxicity. OBJECTIVE: It was aimed to test the toxic effects of Au-TiO2 NPs in the brain, heart, kidney and liver of rats in this work. MATERIALS AND METHODS: All used rats in this work were treated using diverse concentrations (doses) of NPs (100 and 200 mg/kg bw) for 21 days. SOD, CAT, AChE activities and MDA, H2O2, NO contents were evaluated in different organs. RESULTS: The Au-TiO2 NPs exposure induced biochemical changes in different organs of rats in view of oxidative stress and neurotoxicity by the alteration of the activity of the enzyme of neurotransmitter (AChE activity). CONCLUSION: The Au-TiO2 NPs have the potential to interact with rat's biochemical status and cause undesirable effects. One of those damaging effects was oxidative stress and neurotoxicity. CLINICAL SIGNIFICANCE: The study signifies the impact of usage of Au-TiO2 NPs in the medical field for further exploration.

Restructuring of a meiobenthic assemblage after sediment contamination with an antibacterial compound: Case study of ciprofloxacin.

A microcosm experiment was conducted to evaluate the impacts of the fluoroquinolone antibiotic ciprofloxacin on meiobenthic taxa abundance, nematode genus structure, and functional trait parameters. Sediment samples were experimentally enriched with four different doses of ciprofloxacin [D1 (50 ppm Dry weight 'DW'), D2 (100 ppm DW), D3 (200 ppm DW), and D4 (500 ppm DW)] and were then compared with non-enriched sediments (controls). After one month of exposure, the data showed that ciprofloxacin had altered the meiofaunal taxa abundance. A change in the structure of nematofaunal genera was observed, particularly with the highest dose (D4), which was characterized by the lowest taxonomic diversity. The SIMPER analysis revealed that the average dissimilarity between nematode communities increased with increasing doses of ciprofloxacin. Two dimensional (2D) non-metric multidimensional scaling (nMDS) plots and relative abundances of functional groups of nematode genus assemblages revealed that all functional trait abundances were affected, particularly with the highest dose. However, only the amphid shape and feeding group functions showed a clear distribution separation between the control and ciprofloxacin treatments. The nMDS second-stage ordination of inter-matrix rank correlations for matrices including genus and functional traits showed that the tail shape was the closest functional trait to the generic distribution. Thus, only the curves of cumulative dominance related to the tail shape mirrored discernibly the sedimentary concentrations in ciprofloxacin.

The protective effect of Hibiscus sabdariffa calyxes extract against cypermethrin induced oxidative stress in mice.

Cypermethrin (Cyp) is a kind of pyrethroids compound that is broadly used against different species of insects and pests. Cyp can also elicit a range of neurotoxic, immunotoxic, genotoxic and reproductive toxic effects on various experimental organisms. The aim of this study was to evaluate the protective effects of Hibiscus sabdariffa against the toxicity damage induced by Cyp exposure. The Hibiscus sabdariffa calyxes extract was given to mice (200-500 mg/kg bw). The mice, which were treated with Cyp and Hibiscus sabdariffa, were divided into six groups of six mice each. Groups I, IV and VI were used as control and groups II CYP control (20 mg/kg body weight)., groups III and V were treated with Hibiscus sabdariffa extract (200 and 500 mg/kg body weight) plus (20 mg/kg body weight) for 21 days Furthermore, HPLC was used to identify the compound fraction. This result showed Cyp -induced biochemical changes in all organs of mice. Cyp caused decreased CAT activity, inhibition of AChE activity and increased the levels of H2O2 and MDA in brain, heart, liver and kidney. Hibiscus sabdariffa exhibited antioxidant effect and significantly attenuated the neurotoxicity of Cyp. Hibiscus sabdariffa exhibits neuroprotective effects and can be an effective and novel alternative approach to reduce the risk caused by pyrethroid compound.

Protective effect of Zizyphus lotus jujube fruits against cypermethrin-induced oxidative stress and neurotoxicity in mice.

CONTEXT: Cypermethrin (CYP) is a synthetic pyrethroid insecticide used worldwide in agriculture, home pest control. The toxicity of CYP is well studied in many organisms. OBJECTIVE: The aim of present study was to investigate the protective effect of Zizyphus lotus (Zizyp) fruit against neurotoxicity and oxidative stress induced by CYP in mice. MATERIALS AND METHODS: Mice were divided into four groups of six each: groups I and II were used as control and CYP control (20 mg/kg body weight). While, groups III was orally treated with Zizyphus lotus fruit (5 g/kg body weight) plus CYP (20 mg/kg body weight) for 18 days. Furthermore, HPLC-ESI-MS-MS (Q-Tof) and GC-MS were used to identify the compounds fraction. RESULTS: Antioxidant enzyme catalase (CAT), neurotoxicity enzyme acetylcholinesterase (AChE) activities and hydrogen peroxide (H2O2), malondialdehyde (MDA) levels were determined in the liver, kidney and heart. CYP caused decreased CAT activity, inhibition of AChE activity and increased the levels of H2O2 and MDA in heart, liver and kidney. CONCLUSION: Our results indicate that Zizyp fruit is markedly effective in protecting mice against CYP-induced biochemical changes. This protection may be due to its antioxidant property and scavenging ability against active free radicals.

Triangular gold nanoparticles modify shell characteristics and increase antioxidant enzyme activities in the clam Ruditapes decussatus.

CONTEXT: Nanoparticles may cause adverse environmental effects but there is limited information on their interactions with marine organisms. OBJECTIVE: Our aim was to examine the effects of triangular gold nanoparticles (Tr-Au NPs) on the clam, Ruditapes decussatus. MATERIALS AND METHODS: Clams were exposed to Tr-Au1 = 5 µg/L and Tr-Au2 = 10 µg/L for 2 and 7 days. Effects on shell structure were investigated. Superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST) activities, protein carbonyl levels and malondialdehyde content were used to assess biochemical status. RESULTS: Transmission electron microscopy (TEM) and electron dispersive X-ray microanalysis (EDX) showed that Tr-Au NPs modified shell structure and morphology. Tr-Au NPs size increased forming aggregate particles. Tr-Au NPs increased SOD, CAT and GST activities in gill and digestive gland in a concentration- and time-dependent manner indicating defence against oxidative stress. Enhanced lipid peroxidation and protein carbonyl levels confirmed oxidative stress. CONCLUSION: Tr-Au NPs cause oxidative stress and affect shell structure of clams. These findings may have relevance to other marine species.

Trophic restructuring (Wieser 1953) of free-living nematode in marine sediment experimentally enriched to increasing doses of pharmaceutical penicillin G.

Trophic structure of free living nematode from Bizerte lagoon was tested by a microcosmic study after 30 days of exposure with 5 increasing doses of pharmaceutical penicillin G (D1: 3 mg L(-1), D2: 30 mg L(-1), D3: 300 mg L(-1), D4: 600 mg L(-1), D5: 700 mg L(-1)). Results showed significant differences between nematode assemblages from undisturbed controls and those from penicillin G treatments. Selective deposit-feeders (1A) or nonselective deposit-feeders (1B), very abundant in the control microcosm, were significantly affected and their dominance declined significantly. Epistrate feeders (2A) were significantly gradual increase for all microcosms treated with penicillin G, appeared to be more tolerant to the antibiotic and to take advantage of the growing scarcity of other trophic groups. Compared to the control microcosms, omnivorous-carnivorous (2B) was found to be higher in all treated microcosms, with the exception of those treated with D5. Trophic index (Σθ(2)) was significantly reduced in all microcosms treated whereas trophic ratio 1B/2A appears to be insignificant.

Diastereomeric and enantiomeric selective accumulation of cypermethrin in the freshwater mussel Unio gibbus and its effects on biochemical parameters.

Synthetic pyrethroids are a family of chiral pesticides with a large number of stereoisomers. Cypermethrin (CYP) is used in a variety of agricultural crops, but also has public health and veterinary uses. In this work, the freshwater mussel (Unio gibbus) was chosen to evaluate the stereoselectivity of CYP through the use of gas chromatography with mass-spectrometry. The effects of CYP on mussels were examined by measuring neurotoxicity and oxidative stress biomarkers during its uptake. The investigation was performed under laboratory conditions using nominal CYP concentrations C1=100 µg/L and C2=150 µg/L over 96 h. Preferential bioaccumulation of cis-CYP isomers was observed. Furthermore, enantiomeric characterization revealed enantioselective accumulation, most probably related to mussel metabolism. Antioxidant enzyme activities (superoxide dismutase (SOD), and catalase (CAT)), and levels of reduced glutathione (GSH) and malondialdehyde (MDA) were determined in digestive gland after 4 days of exposure. CYP significantly inhibited acetylcholine esterase activity, by 51% and 57%, respectively, in mussels treated with 100 and 150 µg/L doses. The highest and lowest CYP concentrations elicited an increase of 67 and 63%, respectively, in SOD activity compared to the controls, while CAT activity was increased by 65 and 73%. A statistically significant decrease in GSH levels (40%) was observed only with the highest CYP concentration tested (150 µg/L). In addition, lipid peroxidation was significantly higher (67%) than in controls. These results provided information on CYP-enantioselective uptake and potential biomarkers that could be effectively applied for the biomonitoring of freshwater ecosystem.

Effects of 2-(4-Methoxyphenyl)-5, 6-trimethylene-4H-1, 3, 2-oxathiaphosphorine-2-sulfide on biomarkers of Mediterranean clams Ruditapes decussatus.

The effects of exposure to a novel synthetic organophosphorus compound, 2-(4-Methoxyphenyl)-5, 6-trimethylene-4H-1, 3, 2-oxathiaphosphorine-2-sulfide (OMTOS) concentrations (Control=0, C1=0.01, C2=0.1, C3=1 and C4=10µg/L) were investigated in the clam Ruditapes decussatus. Vitellogenin (Vg)-like protein levels in haemolymph from males and females were investigated. Concentrations of 1µg/L and 10µg/L significantly decreased Vg levels in male haemolymph after 7 days, whereas significant variations were only found in females treated with 10µg/L. On the other hand, superoxide dismutase (SOD), catalase (CAT) and acetylcholinesterase activities (AChE) in whole soft tissue were measured after 2, 4 and 7 days of exposure to the same series of concentrations. After 2 days of exposure, 0.1, 1, and 10µg/L of OMTOS increased SOD activity significantly, but this decreased with 10µg/L after 4 and 7 days. No changes in CAT activity were observed after 2 days compared to controls. OMTOS significantly reduced AChE activity after 4 and 7 days in treated clams with the highest concentration 10µg/L, but it did not induce significant variations at the other concentrations tested. Our study demonstrates that OMTOS alters biochemical parameters in R. decussatus, even at low concentrations, and suggests differing modes of action of the contaminant. Using clams is a powerful tool to provide valuable insights into possible mechanisms of environmental toxicity of novel synthetic organic products both in non-target organisms and the marine ecosystem. Additionally, our results highlight that biomarker responses facilitate elucidation of putative mechanisms of action of OMTOS in non-target species.

Acute toxicity of cypermethrin on the freshwater mussel Unio gibbus.

Cypermethrin is a synthetic pyrethroid insecticide used worldwide in agriculture, home pest control, food stuff protection and disease vector control. We investigate the potential of cypermethrin to induce oxidative stress and enzyme activities within the gills of freshwater mussel Unio gibbus. This study was carried out under laboratory conditions using two nominal cypermethrin concentrations C1 (100µg/L) and C2 (150µg/L) during 96h. The measured concentrations of cypermethrin using GC-MS-MS in the treatment aquariums were respectively 59.7 µg/L and 97.5µg/L. Antioxidant enzyme activities (superoxide dismutase (SOD) and catalase (CAT)) as well as H2O2, malondialdehyde (MDA) and protein carbonyl (PCO) levels were assessed. An exposure during 96h induced the SOD activity at the highest concentration. The CAT activity and H2O2 level were increased significantly (P<0.05) in gills following a dose-dependent profile. Cypermethrin also generated an increase in malondialdehyde (MDA) levels reaching the highest value at the high concentration. The considered parameters can be used as biomarkers of exposure to cypermethrin. Freshwater mussel U. gibbus can be potentially employed in biomonitoring surveys of such threatened ecosystems.

Impacts of bioremediation schemes for the mitigation of a low-dose anthracene contamination on free-living marine benthic nematodes.

A microcosm experiment was used to examine (1) the effects of different bioremediation schemes on degradation of anthracene and the structure of free-living marine nematodes in a lightly contaminated (4.5 µg g(-1)) sediment from Bizerte lagoon and (2) the responses of the nematode community upon an artificial spiking of a low dose anthracene (1 µg g(-1)). For that purpose sediment microcosms were incubated in laboratory for 40 days. Bioremediation techniques decreased the anthracene contamination, and interestingly, biodegradation were more efficient when anthracene was artificial supplied into the sediment suggesting that the addition of bioavailable anthracene stimulated the bacterial community to adjust towards a PAH-degrading community. Spiking with this low dose of anthracene provoked significant changes in the nematode community structure and abundance, with the elimination of specific species such as Mesacanthion diplechma, the decrease of the dominant species Oncholaimus campylocercoides and the increase in abundance of opportunistic species such as Spirinia parasitifera. This would suggest a low tolerance of the nematode community despite the presence of a weak anthracene contamination in the sediment that could have allow dominance of an anthracene tolerant nematode species. Anthracene toxicity was alleviated in biostimulation treatments, leading to a strong increase in nematode abundance, concomitantly with changes in the nematode community structure; Prochromadorella neapolitana became the most abundant species.

The development of decontamination methods in coastal marine habitats by transplantation of the mussel Mytilus galloprovincialis (Lamarck, 1819): Comparison between in vivo and in situ investigations.

The health status of Mytilus galloprovincialis native from a polluted habitat was surveyed before and after 30 and 60 days of in situ transplantation and in vivo experiments. The results showed a reduction in filtration rate by 24 % and 45 %, respectively, after 60 days of in vivo and in situ experiments compared to the rates at polluted sites. The respiration rate reached a minimum of 0.081 ± 0.05 mg O2.L-1 after 60 days of in situ transplantation. Moreover, the antioxidant activities were changed in a time-dependent manner for both transplantation conditions. The highest superoxide dismutase and catalase activities corresponded to the stressed mussels and declined by 76 % and 54 %, respectively, after 60 days of in situ transplantation. Changes in lipid peroxidation and acetylcholinesterase activity were observed in internal organs following 60 days of transplantation. At this time slot, the lowest content of metals and microplastics was also noticed.

Physiological Impairment and Biochemical Modifications Induced by Triclosan in Mediterranean Mussels.

The effects of pharmaceutical under aquatic biota are still not well established. In this investigation, we assessed the results of a common pharmaceutical's, triclosan (TCS), treatment on physiological and biochemical status of the Mediterranean mussels. Filtration and respiration rates were statistically reduced after treatment with highest considered concentration TCS2 = 100 µg·L-1. However, no modification (p > 0.05) was detected after treatment with TCS1 = 50 µg·L-1. For biochemical responses, oxidative stress parameters including H2O2 level and antioxidant enzymes were enhanced following concentration in considered organs. In parallel, Malondialdheyde content was measured in mussels after TCS treatment and lipid peroxidation occurred at high TCS concentration. Neurotoxicity evaluated by acetylcholinesterase (AChE) activity was induced in gills and digestive glands after exposure to TCS2. Overall, physiological impairment, oxidative stress, lipid peroxidation and neurotoxicity could be induced by triclosan in mussels. The association of physiological and biochemical biomarkers constitute a useful tool to measure the impact of pharmaceuticals in marine organism.

Acute toxicities of cadmium and permethrin on the pre-spawning and post-spawning phases of Hexaplex trunculus from Bizerta Lagoon, Tunisia.

Marine gastropods, exposed to anthropogenic pollution, accumulate high chemical concentrations in their tissues, especially in the digestive glands. An evaluation of the impacts of cadmium (Cd) and permethrin (Perm), coupled with reproductive events (pre-spawning and post-spawning phase) throughout the year, was attempted by measuring catalase (CAT), a biomarker of defence, on Hexaplex trunculus experimentally exposed for 48 or 96 h. Specimens of gastropods were sampled from Bizerta Lagoon (Tunisia). The results show that CAT activity increased in gastropods exposed to the three cadmium concentrations (C1 Cd, 100 µg L(-1); C2 Cd, 200 µg L(-1); and C3 Cd, 300 µg L(-1)) and to the three permethrin doses (C1 Perm, 100 µg L(-1); C2 Perm, 150 µg L(-1); and C3 Perm, 200 µg L(-1)) tested. A decrease in CAT was noted in the digestive gland of the H. trunculus exposed to permethrin at the concentration of 200 µg L(-1) during the pre-spawning and post-spawning phases. H. trunculus in post-spawning was more sensitive to cadmium and permethrin than in the pre-spawning phase. The biochemical responses to pollutants (cadmium and permethrin) represented by CAT may act as a biomarker of exposure in this species.

Diuron environmental levels effects on marine nematodes: Assessment of ecological indices, taxonomic diversity, and functional traits.

Coastal marine systems are the most sensitive zones to emerging pollutants. The present study aims to investigate the effect of Diuron on the meiofaunal assemblages, collected from the Bizerte channel (Tunisia). Microcosm experiments were set up using four increasing Diuron concentrations [D1 (10 ng g-1 dry weight (DW)), D2 (50 ng g-1 DW), D3 (250 ng g-1 DW) and (1250 ng g-1 DW)] compared to non-contaminated sediments (controls) and all plots were incubated for 30 days. Our results show that Diuron-supplemented sediments provoked the significant decrease of meiofaunal abundance as well as a change in nematodes' diversity and structure composition. All univariate indices, as well as the cumulative k-dominance, were lower in the Diuron than the control plot. Additionally, the ordination of treatments according to the two-dimensional nMDS plots analysis showed a clear structural separation of the Diuron treated replicates from the controls based on the functional groups lists. These current data emphasize the utility of the use of biological traits in the detection of disturbances in the aquatic biotope.

Effectiveness of Shewanella oneidensis bioaugmentation in the bioremediation of phenanthrene-contaminated sediments and possible consortia with omnivore-carnivore meiobenthic nematodes.

This study was conducted to assess the impact and efficiency of the bioaugmentation as a bioremediation technique in annoying effects of a polycyclic aromatic hydrocarbon (phenanthrene) on a community of free-living nematodes from Bizerte bay (Tunisia). For this purpose, closed microcosms were exposed to three doses of phananthrene (0.1 µg kg-1, 1 µg kg-1 and 10 µg kg-1), in combination or not with a strain of Shewanella oneidensis. After 40 days of the exposure, results were obtained at the numerical, taxonomic and feeding levels. The results of univariate analyses revealed significant decreases in most univariate indices for phenanthrene treated communities compared to controls, with a discernible increase in the proportion of epistrate feeders. After bioaugmentation, similar patterns were observed for univariate and multivariate analyses, with the exception of the highest treatment, which showed no difference from the controls. The results obtained showed that the bioaugmentation with Shewanellea oneidensis was highly effective in reducing the negative impact of the highest dose of phenanthrene (10 µg kg-1 Dry Weight) tested on meiobenthic nematodes. Furthermore, a combination of Shewanellea oneidensis and four omnivore-carnivore nematode taxa could be suggested as an effective method in the bioremediation of phenanthrene-contaminated sediment.

Microbial diversity alteration reveals biomarkers of contamination in soil-river-lake continuum.

Microbial communities inhabiting soil-water-sediment continuum in coastal areas provide important ecosystem services. Their adaptation in response to environmental stressors, particularly mitigating the impact of pollutants discharged from human activities, has been considered for the development of microbial biomonitoring tools, but their use is still in the infancy. Here, chemical and molecular (16S rRNA gene metabarcoding) approaches were combined in order to determine the impact of pollutants on microbial assemblages inhabiting the aquatic network of a soil-water-sediment continuum around the Ichkeul Lake (Tunisia), an area highly impacted by human activities. Samples were collected within the soil-river-lake continuum at three stations in dry (summer) and wet (winter) seasons. The contaminant pressure index (PI), which integrates Polycyclic aromatic hydrocarbons (PAHs), alkanes, Organochlorine pesticides (OCPs) and metal contents, and the microbial pressure index microgAMBI, based on bacterial community structure, showed significant correlation with contamination level and differences between seasons. The comparison of prokaryotic communities further revealed specific assemblages for soil, river and lake sediments. Correlation analyses identified potential "specialist" genera for the different compartments, whose abundances were correlated with the pollutant type found. Additionally, PICRUSt analysis revealed the metabolic potential for pollutant transformation or degradation of the identified "specialist" species, providing information to estimate the recovery capacity of the ecosystem. Such findings offer the possibility to define a relevant set of microbial indicators for assessing the effects of human activities on aquatic ecosystems. Microbial indicators, including the detection of "specialist" and sensitive taxa, and their functional capacity, might be useful, in combination with integrative microbial indices, to constitute accurate biomonitoring tools for the management and restoration of complex coastal aquatic systems.

Effects of benzo(a)pyrene on meiobenthic assemblage and biochemical biomarkers in an Oncholaimus campylocercoides (Nematoda) microcosm.

A microcosm experiment was carried out to determine how benzo(a)pyrene (BaP) may affect marine meiofauna community, with a main emphasis on nematode structure and functional traits. Three increasing concentrations of BaP (i.e. 100, 200 and 300 ng/l, respectively) were used for 30 days. The results revealed a gradual decrease in the abundance of all meiobenthic groups (i.e. nematodes, copepods, amphipods, polychaetes and oligochaetes), except for isopods. Starting at concentrations of 200 and 300 ng/l BaP, respectively, significant changes were observed at community level. At taxonomic level, the nematode communities were dominated at the start of the experiment and also after being exposed or not to BaP by Odontophora villoti, explicable through its high ecologic ubiquity and the presence of well-developed chemosensory organs (i.e. amphids), which potentially increased the avoidance reaction following exposure to this hydrocarbon. Moreover, changes in the activity of several biochemical biomarkers (i.e. catalase 'CAT', gluthatione S-transferase 'GST', and ethoxyresorufin-O-deethylase 'EROD') were observed in the nematode species Oncholaimus campylocercoides, paralleled by significant decreases in CAT activity for non-gravid females compared to controls at concentrations of 25 ng/l BaP and associated with significant increase in GST and EROD activities for both types of individuals.

The response of meiobenthinc sediment-dwelling nematodes to pyrene: Results from open microcosms, toxicokinetics and in silico molecular interactions.

An experiment conducted with 'open microcosm' made by connected sedimentary compartments with different qualities was for 30 days to evaluate the migratory behaviour of nematodes as induced by exposure to pyrene. The nematofauna was collected along with sediment from a reference site in Bizerte lagoon. Following one week acclimatization period, the populated sediments were topped with azoic sediments, with a pyrene concentration of 150 µg kg-1. The concentration of pyrene from sediments was measured on a weekly basis. A stable status of nematode assemblages was reached between the upper and lower compartments in each microcosm, whatever the treatment type. An upward exploratory phase was observed during the first two weeks within the assemblages, possibly induced by the repellent chemodetection of pyrene. This observation was confirmed by the toxicokinetic properties and molecular interactions of pyrene with the germ-line development Protein 3 and sex-determining protein of Caenorhabditis elegans as nematode model.