Bioaccumulation Of Xenobiotics Research Articles

Assessment of PAHs accumulation in Donax trunculus (Linnaeus, 1758) (Bivalvia, Donacidae) from the Bulgarian Black Sea Coast

Anthropogenic pollution of marine ecosystems is one of the main sources of polycyclic aromatic hydrocarbons (PAHs). Marine bivalves are often used as bioindicators of environmental pollution due to their wide distribution and capability of xenobiotic bioaccumulation. The aim of the present study was to assess the presence of PAHs in soft tissues of wedge clams Donax trunculus (Linnaeus, 1758), collected from sublittoral sandy habitats at different locations off the Bulgarian Black Sea coast. Wedge clams from the different locations showed variations in the content of accumulated PAHs’ compounds. The concentrations of PAHs were measured by gas chromatography system with mass spectrometry detection. The total PAHs content (sum of 13 PAHs’ compounds) measured was in the range from 5.59 to 50.50 ng/g wet weight and was comparable with other European studies. The compounds phenanthrene and fluorene were most abundant in all analyzed samples. The results showed that low molecular weight (LMW) PAHs (2 and 3 aromatic rings) were predominant, accounting for 91% of the total PAHs levels, while high molecular weight (HMW) PAHs (4–5- and 6- rings) presence was 8.9% on average. The ratio LMW/HMWPAHs was higher than one, suggesting predominant pollution of petrogenic origin. The concentrations of benzo (a)pyrene did not exceed the limit set in EC Regulation although it was detected in 20% of the analyzed samples. In conclusion, maximum overall PAHs content was found in clams from Arkutino, while minimum PAHs content was present in samples from Elenite. The Sum PAH4 (sum of four polycyclic aromatic hydrocarbons: benzo[a]pyrene, chrisene, benzo[a]anthracene, and benzo[b]fluoranthene) in the wedge clams for all localities studied was below legislation limits. Data from the present research can be used for assessing pollution levels in the marine environment and also risk of human exposure to PAHs using D. trunculus as bioindicator species.

THE USE OF BIO-MOLECULAR SUBSTANCE OF MARINE BIOTA AS AN ALTERNATIVE EARLY INDICATOR OF OIL POLLUTED ENVIRONMENT: A NEW APPROACH FOR MONITORING CONSIDERATION

THE USE OF BIO-MOLECULAR SUBSTANCE OF MARINE BIOTA AS AN ALTERNATIVE EARLY INDICATOR OF OIL POLLUTED ENVIRONMENT: A NEW APPROACH FOR MONITORING CONSIDERATION

Rhizofiltration of combined arsenic-fluoride or lead-fluoride polluted water using common aquatic plants and use of the ‘clean’ water for alleviating combined xenobiotic toxicity in a sensitive rice variety

Groundwater co-contamination with toxic pollutants like arsenic-fluoride or lead-fluoride is a serious threat for safe rice cultivation, since major stretches of land, involved in cultivation of this staple food crop are presently experiencing severe endemic pollution from these xenobiotic combinations. Preliminary investigations established that the combined pollutants together exerted more phytotoxicity in the widely cultivated indica rice variety Khitish, compared with that exerted by the individual contaminants. Thus, an ecologically sustainable and economically viable phytoremediative strategy was designed where three aquatic plants, viz., Azolla (water fern), Pistia (water lettuce) and Eichhornia (water hyacinth) (commonly located across the co-polluted regions) were tested for their ability to rhizofiltrate the water samples that had been polluted with arsenic-fluoride or lead-fluoride. Water lettuce exhibited the highest ability to ‘clean’ both arsenic-fluoride and lead-fluoride polluted water due to its capacity of efficient phytoextraction and phytostabilization. Irrigation of Khitish seedlings with this de-polluted water appreciably reduced malondialdehyde formation, electrolyte leakage and irreversible protein carbonylation due to suppression in NADPH oxidase activity and reactive oxygen species production, compared with those in sets grown with non-treated, arsenic-fluoride or lead-fluoride contaminated water. Oxidative injuries, cytotoxic methylglyoxal synthesis and inhibition of biomass growth were ameliorated, and chlorophyll synthesis and Hill activity were increased due to reduced bioaccumulation of xenobiotics, along with the improved uptake of vital micronutrients like iron, copper and nickel. Overall, the current investigation illustrated a cheap, farmer-friendly blueprint which could be easily promulgated to ensure safe rice cultivation even across territories that are severely co-polluted with the mixed contaminants.

Transfer of 7 Organic UV Filters from Sediment to the Ragworm Hediste diversicolor: Bioaccumulation of Benzophenone-3 and Further Proof of Octocrylene Metabolism

Organic UV filters are continuously released in aquatic ecosystems due to their widespread use, especially in touristic coastal environments. Generally, organic UV filters are poorly soluble in water and tend to accumulate in the sediment compartment. This represents a conceivable risk for sediment-dwelling organisms and a potential for transfer of the UV filters up the food chain. This study aimed to assess the potential transfer of seven UV filters including benzophenone-3 (BP3), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), butyl methoxydibenzoylmethane (BM), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), 2-ethylhexyl salicylate (ES), diethylhexyl butamido triazone (DBT), and octocrylene (OC) from artificial spiked sediment (10 µg.g−1 dry weight) to sediment-dwelling worms. All UV filters were detected in the worms after 28 days of exposure, but only BP3 was apparently bioaccumulated, with a biota sediment accumulation factor (BSAF) of 12.38 ± 4.65. However, metabolomic profiling revealed that OC was metabolized by the worms into 11 fatty acid conjugates, demonstrating that OC did also accumulate in the worms in the form of OC–fatty acid conjugates. Here, the sole quantification of the parent organic UV filter underestimated the accumulation factor and the exposure of organisms. In general, it is therefore important to pair the conventional method (BSAF calculus) with other techniques, such as metabolomics, to assess the actual potential for bioaccumulation of xenobiotics including transformed xenobiotics.

Targeted and untargeted metabolomic analysis of Procambarus clarkii exposed to a “chemical cocktail” of heavy metals and diclofenac

Water pollution poses an important problem, but limited information is available about the joined effects of xenobiotics of different chemical groups to evaluate the real biological response. Procambarus clarkii (P. clarkii) has been demonstrated to be a good bioindicator for assessing the quality of aquatic ecosystems. In this work, we studied the bioaccumulation of cadmium (Cd), arsenic (As) and diclofenac (DCF) in different tissues of P. clarkii during 21 days after the exposure to a “chemical cocktail” of As, Cd and DCF, and until 28 days considering a depuration period. In addition, a combined untargeted and targeted metabolomic analysis was carried out to delve the metabolic impairments caused as well as the metabolization of DCF. Our results indicate that As and Cd were mainly accumulated in the hepatopancreas followed by gills and finally abdominal muscle. As and Cd show a general trend to increase the concentration throughout the exposure experience, while a decrease in the concentration of these elements is observed after 7 days of the depuration process. This is also the case in the abdominal muscle for Cd, but not for As and DCF, which increased the concentration in this tissue in the depuration phase. The hepatopancreas showed the greatest number of metabolic pathways affected. Thus, we observed a crucial bioaccumulation of xenobiotics and impairments of metabolites in different tissues. This is the first study combining the exposure to metals and pharmaceutically active compounds in P. clarkii by untargeted metabolomics including the biotransformation of DCF.

Gut Microbial Profiles in Nereis succinea and Their Contribution to the Degradation of Organic Pollutants.

Gut microbiota of wildlife are usually exposed to and involved in degrading environmental pollutants, yet their biodegrading capacity remains largely unexplored. Here, we analyzed gut microbial profiles of a marine benthic polychaete, Nereis succinea, and elaborated the capacity of gut microbiota in degrading various organic pollutants, including polycyclic aromatic hydrocarbons, pesticides, phenols, and synthetic musks. High-throughput sequencing analysis revealed that the structures of microbial communities, including bacteria, fungi, and archaea, varied along the gut, manifesting distinct structural features in the fore-, mid-, and hindgut regions. Community-level physiological profiles and the capacity of gut microbiota in degrading the pollutants showed profound gut region and oxygen dependent features. In general, anaerobes were more active in degrading the pollutants, and those in the midgut presented the maximum degrading potential. Degradation capability of the gut microbiota was further quantitatively validated in an in vitro culture system using chlorpyrifos and malathion as representative compounds. Our results demonstrated a potential impact of gut microbiota in wildlife on the fate of organic pollutants in the ecosystem, which calls for further research on the influences of gut microbiota on biotransformation and bioaccumulation of xenobiotics in organisms.

Influence of ultra-small particles (10-20 nm) in the atmospheric air of Chernivtsi during intrauterine development on the course of sepsis in newborns

Unfavorable environmental factors that affect parents cause impaired programmed development, the fetus, especially in its sensitive period. Even environmental factors of low intensity due to the bioaccumulation of xenobiotics in maternal tissues and their release to the bloodstream during pregnancy can have a pathogenic effect on the fetus, especially during sensitive periods of its development. To analyze the influence of the content of ultra-small particles (10-20 nm) in the atmospheric air during prenatal development on the course of sepsis in newborns. Based on the results of the analysis of content in the atmospheric air, two clinical observation subgroups were formed. The first subgroup included 17 patients with neonatal sepsis in whom the UFPs content in the air exceeded1.0 inone of the periods. The second subgroup consisted of 35 newborns with sepsis in whom the content of UFPs 10-20 nm in the atmospheric air was less than1.0 inone of these periods. The content in the atmospheric air of ultra-small particles (10-20 nm) during the sensitive period of pre-natal development did not significantly affect the gestational age of newborns, the content in their blood in the presence of sepsis of interleukins-6, -8, -10, pressepsin, procalcitonin, C-RP and immunoglobulins of classes A, G, M, as well as the duration of intensive care and inpatient care.

Characterization of Species Differences in Xenobiotic Metabolism in Non-experimental Animals

The ability to metabolize xenobiotics in organisms has a wide degree of variation among organisms. This is caused by differences in the pattern of xenobiotic bioaccumulation among organisms, which affects their tolerance. It has been reported in the veterinary field that glucuronidation (UGT) activity in cats, acetylation activity in dogs and sulfation (SULT) activity in pigs are sub-vital in these species, respectively, and require close attention when prescribing the medicine. On the other hand, information about species differences in xenobiotics metabolism remains insufficient, especially in non-experimental animals. In the present study, we tried to elucidate xenobiotic metabolism ability, especially in phase II UGT conjugation of various non-experimental animals, by using newly constructed in vivo, in vitro and genomic techniques. The results indicated that marine mammals (Steller sea lion, northern fur seal, and Caspian seal) showed UGT activity as low as that in cats, which was significantly lower than in rats and dogs. Furthermore, UGT1A6 pseudogenes were found in the Steller sea lion and Northern fur seal; all Otariidae species are thought to have the UGT1A6 pseudogene as well. Environmental pollutants and drugs conjugated by UGT are increasing dramatically in the modern world, and their dispersal into the environment can be of great consequence to Carnivora species, whose low xenobiotic glucuronidation capacity makes them highly sensitive to these compounds.

Phenanthrene bioaccumulation in the nematode Caenorhabditis elegans.

The contribution of food to the bioaccumulation of xenobiotics and hence toxicity is still an ambiguous issue. It is becoming more and more evident that universal statements cannot be made, but that the relative contribution of food-associated xenobiotics in bioaccumulation depends on species, substance, and environmental conditions. Yet, small-sized benthic or soil animals such as nematodes have largely been disregarded so far. Bioaccumulation of the polycyclic aromatic hydrocarbon phenanthrene in the absence and presence of bacterial food was measured in the nematode Caenorhabditis elegans. Elimination of phenanthrene in the nematodes was biphasic, suggesting that there was a slowly exchanging pool within the nematodes or that biotransformation of phenanthrene took place. Even with food present, dissolved phenanthrene was still the major contributor to bioaccumulated compound in nematode tissues, whereas the diet only contributed about 9%. Toxicokinetic parameters in the treatment without food were different from the ones of the treatment with bacteria, possibly because nematodes depleted their lipid reserves during starvation.

Enhanced bioaccumulation of dietary contaminants in catfish with exposure to the waterborne surfactant linear alkylbenzene sulfonate

Fish bioaccumulate a variety of contaminants and act as an exposure portal to the human consumer. Surfactants, known pharmaceutically to alter membrane permeability, change drug bioavailability and attenuate transporter function are also found in contaminant mixtures in the aquatic environment. The overall objective of this study was to determine if the surfactant C-12 linear alkylbenzene sulfonate (LAS) at environmentally relevant concentrations, alters the disposition and enhances bioaccumulation of co-exposed dietary xenobiotics in the catfish. Included for study were the carcinogen benzo(a)pyrene (BaP), pharmaceutical, ivermectin (IVM), and P-glycoprotein (P-gp) substrate rhodamine 123 (Rho-123), each exhibiting different dispositional footprints. Rho-123 transport into bile and membrane fluidity was examined in isolated perfused livers from control and LAS exposed catfish. Mass balance residue assessments were performed on catfish following in vivo exposure for 12 days to LAS in water at 0, 100 or 300 μg/L with 6 days of 3H-IVM or 3H-BaP gavage treatments. LAS at 1, 5 and 20 μM in the perfused liver, significantly decreased the transport of Rho-123 (1 μM) into bile by 18.6, 38.1 and 66.7%, respectively. Fluorescence anisotropy measurements demonstrated a 29.7% increase in fluidity at the (1 μM, 348 μg/L) LAS concentration. In vivo mass balance studies indicated that waterborne LAS (100 and 300 μg/L) increased the dietary dose remaining in fish by 39% and 78% for 3H-IVM and 50 and 157% for 3H-BaP. LAS at environmentally relevant concentrations altered the bioavailability and disposition of dietary xenobiotics in the catfish. Co-exposure with LAS increases xenobiotic bioaccumulation, potential toxicity of mixture components to the fish and the potential for residue transfer from fish to the consumer.

A multibiomarker approach in Coris julis living in a natural environment

To monitor the health of aquatic organisms, biomarkers have been used as effective tools in assessing environmental risk. In this study was examined the teleost Coris julis, sampled in two marine sites in Messina (Italy) at different pollution degree, Milazzo, characterized by a strong anthropogenic impact, and Marinello, the natural reserve. C. julis is a species particularly suitable to biomonitoring because its feeding habits favor bio-accumulation of xenobiotics. The following biomarkers were used to estimate the impact of highly persistent pollutants: cellular localization of cytochrome P4501A (CYP1A) and glutathione-S-transferase (GST) in the liver, their hepatic expression at the mRNA level, the enzymatic activity (EROD and BPMO), the micronucleus and comet assays in the blood, esterases (AChE in the brain and BChE in the blood) activity and evaluation of PAH metabolites in the bile. The present findings provide evidence of statistically significant differences in parameters between individuals collected in two sites.

Liver microsomes and S9 from rainbow trout (Oncorhynchus mykiss): Comparison of basal‐level enzyme activities with rat and determination of xenobiotic intrinsic clearance in support of bioaccumulation assessment

Metabolism plays an important role in bioaccumulation of xenobiotics in fish. The applicability of trout liver microsomes and S9 fraction in bioaccumulation assessment of xenobiotics in fish was investigated in the present study. Basal-level activities of 7-ethoxyresorufin-O-dealkylase, testosterone 6beta-hydroxylase, glutathione-S-transferase, and uridine 5'-diphospho-glucuronosyltransferase in trout liver microsomes and S9 were significantly lower than those in rat liver microsomes and S9. The in vitro-to- in vivo scaling factors, which are the values of liver microsomal and S9 protein contents per unit weight of trout liver, were determined to be 38.4 +/- 5.1 (mean +/- standard deviation throughout) and 95.9 +/- 11.9 mg/g, respectively. Intrinsic clearance (CL(int)) values for a number of reference compounds obtained from trout liver S9 were lower than those from trout liver microsomes. After correction with the scaling factors, trout liver microsomes and S9 provided equivalent prediction of trout hepatic clearance (CL(H)) using the well-stirred liver model, but their CL(H) values were significantly lower than those obtained from freshly isolated trout hepatocytes. Consequently, trout liver microsomes and S9 showed poorer prediction of the bioconcentration factors of the reference compounds compared with trout hepatocytes. Unit conversion revealed that CL(int) values obtained from trout liver microsomes and S9 were 6.3 to 22.4% of those from trout hepatocytes, which explained, to a large extent, the differences in their CL(H) and bioconcentration factor prediction.

Xenobiotic intrinsic clearance in freshly isolated hepatocytes from rainbow trout ( Oncorhynchus mykiss): Determination of trout hepatocellularity, optimization of cell concentrations and comparison of serum and serum-free incubations

Metabolism plays an important role in bioaccumulation of xenobiotics in fish. In vitro determination of xenobiotic intrinsic clearance (CL int) in trout hepatocytes and subsequent extrapolation to in vivo hepatic clearance (CL H) using the “well-stirred” liver model greatly improved our current practice of bioaccumulation assessment [Han, X., Nabb, D.L., Mingoia, R.T., Yang, C.H., 2007. Determination of xenobiotic intrinsic clearance in freshly isolated hepatocytes from rainbow trout ( Oncorhynchus mykiss) and rat and its application in bioaccumulation assessment. Environ. Sci. Technol. 41, 3269–3276]. In an effort to further optimize this approach, we experimentally obtained the value of trout hepatocellularity ( H T), a key scaling factor in the “well-stirred” liver model. H T was determined to be (540 ± 12) × 10 6 cells/g liver for male trout. We also investigated the potential effect of different cell concentrations on the determination of CL int values of molinate, 4,4-bis(dimethylamino)benzophenone, 4-nonylphenol, 2,4-di- tert-butylphenol, and benzo(a)pyrene. Linear relationships were established between clearance rates and cell concentrations at 1 × 10 6, 2 × 10 6, 5 × 10 6, and 10 × 10 6 cells/mL. This suggests that under our experimental conditions, CL int determination was independent of hepatocyte concentrations. In order to better understand the “in vitro binding” effect in in vitro-to-in vivo scaling, we obtained CL int values for the above-mentioned compounds in trout hepatocytes that were suspended in trout serum. Incubations in serum, in general, resulted relatively larger prediction of CL H values. Our findings suggest that in bioaccumulation assessment, the traditional medium incubation method offers a conservative estimate on fish metabolism of xenobiotics and the serum incubation approach could be used for certain classes of compounds that are of challenge for in silico prediction of their plasma and in vitro binding properties.

Determination of Xenobiotic Intrinsic Clearance in Freshly Isolated Hepatocytes from Rainbow Trout (Oncorhynchus mykiss) and Rat and Its Application in Bioaccumulation Assessment

Bioaccumulation in fish depends on the dynamics of various processes that involve fish uptake, storage, and elimination of xenobiotics. Elimination via fish biotransformation is a primary process that can be evaluated in an in vitro system to improve the performance of the prediction of xenobiotic bioaccumulation potentials. In this study, values of intrinsic clearance (CLint) of seven reference compounds (atrazine, molinate, 4,4-bis(dimethylamino)-benzophenone, 4-nonylphenol, 2,4-di-tert-butylphenol, trifluralin, benzo(a)pyrene) in hepatocytes freshly isolated from rainbow trout and rat were determined using a substrate depletion approach. Atrazine was metabolized in rat hepatocytes with a CLint value of 3.81 +/- 1.96 mL/h/ 10(6) cells, whereas in trout hepatocytes, the clearance was not significant until very high cell concentration was used and the rate was estimated to be approximately 0.002 mL/h/10(6) cells. Intrinsic clearance values for all other compounds were 5.5-78.5-fold lower in trout hepatocytes than those in rat hepatocytes. Trout hepatic clearance (CL(H)) values were extrapolated from the CLint values using a "well-stirred" liver model. Biotransformation rate constants (kMET) of the compounds in trout were subsequently estimated and used as inputs to a kinetic model for the prediction of bioconcentration factors (BCF) in fish. Compared to the BCF values predicted without consideration of fish biotransformation, the inclusion of estimated kMET values significantly improved fish BCF predictions for the reference compounds. This study demonstrates a framework for future bioaccumulation assessment of xenobiotics using combined information of the physical-chemical properties of the compounds and the biotransformation potentials of the compounds in fish.

Comparison of basal level metabolic enzyme activities of freshly isolated hepatocytes from rainbow trout ( Oncorhynchus mykiss) and rat

Biotransformation plays a key role in detoxification, bioactivation and bioaccumulation of xenobiotics in fish. Biotransformation capabilities in fish, however, are not as thoroughly characterized as in mammals. In this study, basal level activities of 7-ethoxyresorufin O-dealkylase (EROD), 7-methoxyresorufin O-dealkylase (MROD), 7-pentoxyresorufin O-dealkylase, chlorzoxazone 6-hydroxylase, testosterone 6β-hydroxylase, lauric acid 11-hydroxylase, and glutathione S-transferase in freshly isolated hepatocytes from rainbow trout ( Oncorhynchus mykiss) and rat were obtained and compared. All the activities, when normalized to cellular protein concentrations, were significantly lower in rainbow trout hepatocytes than those in rat hepatocytes. Rainbow trout cytochrome P450 (CYP) 2B-, 2E1-, and 3A-like activities were respectively 14-, 18.4-, and 11.8-fold lower than rat. The smallest difference between the two species was CYP1A-type activities (EROD and MROD, 3.4- and 3.7-fold lower in rainbow trout, respectively). Our results suggest that the relative importance of CYP1A enzymes (among CYP subfamilies) in the biotransformation of xenobiotics in rainbow trout is likely much greater than that in mammals.

Cholinesterase activities in the adductor muscle of the Antarctic scallop Adamussium colbecki

Antarctica is regarded as one of the most pristine parts of the Earth but even this remote ecosystem is affected by contamination and high levels of certain heavy metals, such as cadmium, which may occur naturally in Antarctic waters. The bivalve scallop Adamussium colbecki is considered a key species of Antarctic benthic ecosystems and a sensitive target for bioaccumulation of xenobiotics and metals. Since cholinesterases (ChEs) in the adductor muscle of A. colbecki presumably play a prominent physiological role through regulation of swimming movements, the main aims of this study was to characterize ChE activities in adductor muscle of A. colbecki and to investigate their sensitivity to organophosphate pesticides and heavy metals. The results suggest that an acetylcholinesterase-like enzyme in the adductor muscle of the scallop has low sensitivity to organophosphates but was significantly inhibited by exposure to cadmium.

Oxidative stress in the mussel Mytella guyanensis from polluted mangroves on Santa Catarina Island, Brazil

Digestive glands of the mangrove mussel Mytella guyanensis, collected at one non-polluted site (site 1) and two polluted sites (sites 2 and 3), were analysed for different antioxidant defenses, lipid peroxidation and DNA damage. Thiobarbituric acid-reactive substance (TBARS) and 8-oxo-7,8-dihydro-2 ′-deoxyguanosine levels were enhanced at the polluted sites. With the exception of superoxide dismutase, the activities of catalase and glutathione peroxidase were also higher at the polluted sites. Greater increases were observed in glutathione reductase, glutathione S-transferase and etoxyresorufine- O-deethylase activities at the polluted sites. Conversely, reduced glutathione content was higher at the control site. Trace metal contents in mussels collected at polluted sites were increased compared to the control site, and there were strong positive correlations between TBARS and Cu and Pb contents. M. guyanensis is routinely exposed to an oxidative stress condition at both polluted sites, and considering xenobiotic bioaccumulation in bivalve molluscs, the mangrove mussel represents an excellent bioindicator for environmental monitoring studies.