Xenobiotic Contaminants Research Articles

Biomarkers for endocrine disruptors in three species of Mediterranean large pelagic fish

The hypothesis that Mediterranean top predator species, such as large pelagic fish, are potentially at risk due to endocrine disrupting chemicals (EDCs), is investigated. The potential estrogenic effects of PHAHs in three fish species of commercial interest, the top predators bluefin tuna (Thunnus thynnus thynnus), swordfish (Xiphias gladius), and Mediterranean spearfish (Tetrapturus belone), were investigated using vitellogenin (Vtg), zona radiata proteins (Zrp) and mixed function oxidases (EROD, BPMO) as diagnostic tools. High induction of Vtg and Zrp was detected by western blot and ELISA techniques in adult males of X. gladius and T. thynnus thynnus, suggesting that these species are at high toxicological risk in the Mediterranean sea. Comparison of BPMO and EROD activities in the three species indicated, both in male and female, much higher MFO activity in bluefin tuna. This data suggests high exposure of this species to lipophilic xenobiotic contaminants in the Mediterranean environment.

An automatic method for the evaluation of xenobiotic toxicity on haematopoietic progenitors

Culture of haematopoietic progenitors is used in toxicology to evaluate the effects of xenobiotic contaminants on humans. One of the most important parts of this analysis is the quantification of cell aggregates in the culture. These aggregates can have different sizes and shapes, which reflect the category of cells (granulocyte or monocyte), and the growth percentage reflects the toxic effect of the contaminant. A proposal for an automatic method based on image analysis is described in this work. Algorithms able to solve the basic problems are proposed and tested, and the problem concerning a tridimensional analysis is exposed and discussed.

Skin biopsy of Mediterranean cetaceans for the investigation of interspecies susceptibility to xenobiotic contaminants

Various studies on Mediterranean cetaceans have revealed bioaccumulation of contaminants such as organochlorines (OCs) and heavy metals. The susceptibility of these animals to organic pollutants and the relationship between bioaccumulation and population decline (as in the case of Delphinus delphis) are unexplored fields. In this study, we used a non-destructive approach (skin biopsy) to explore OC bioaccumulation processes and mixed-function oxidase activity (BPMO) in four species of cetaceans: striped dolphin ( Stenella coeruleoalba), bottlenose dolphin ( Tursiops truncatus), common dolphin ( D. delphis) and fin whale ( Balaenoptera physalus). Significant differences in BPMO induction and OC levels were found between odontocetes and mysticetes, the former having mixed-function oxidase activities four times higher than the latter, binding with levels of OCs one order of magnitude higher in odontocetes. A significant correlation ( P<0.05) between BPMO activities and OC levels was found in B. physalus. In an ongoing project, fibroblast cultures have been used as an alternative in vitro method of evaluating interspecies susceptibility to contaminants such as OCs and polycyclic aromatic hydrocarbons (PAHs). These results suggest that cetacean skin biopsies are a powerful non-invasive tool for assessing ecotoxicological risk to Mediterranean marine mammals species.

Reduced genetic diversity in a meiobenthic copepod exposed to a xenobiotic

Populations that encounter a novel environment can lose genetic diversity. Intense, directional selection can affect reproduction and lead to a gene pool dominated by relatively few genotypes. A loss of haplotype diversity ( h) in the mitochondrial genome in populations of meiobenthic, harpacticoid copepods around offshore oil platforms has been linked to lethal and sublethal responses to factors proximal to offshore oil platforms. However, it was not possible to determine if the effects were related directly to increased concentrations of contaminants produced by drilling at the platforms. An experiment was designed to test whether populations of Nitocra lacustris Schmankevitsch (Copepoda: Harpacticoida) would lose haplotype diversity over 3 generations following exposure to sediment-associated hydrocarbons. Haplotype diversity was estimated by comparing restriction fragment length polymorphisms generated from mitochondrial DNA amplified from individual copepods. An additional component of the study was to determine the effects of population size on estimates of diversity. Haplotype diversity could be underestimated by using too few individuals, because random genetic drift in very small populations could cause lower diversity even in the absence of strong selection. The relationship between sample size and h was determined by randomly sub-sampling, at different sample sizes, a large data set collected for two copepod species. Cultures treated with phenanthrene, a polycyclic aromatic hydrocarbon, experienced lower adult survival, fewer surviving offspring per female, and lower haplotype diversity relative to control cultures. After the first generation, mortality declined, but larval survival and haplotype diversity did not change in subsequent generations. Diversity was slightly underestimated due to assaying too small a number of individuals, but could not account for all of the differences between treatments. Despite mortality, populations in culture were not reduced to the point where random drift seemed to have a significant effect. These results support the hypothesis that loss of mtDNA diversity in naturally occurring populations of Harpacticoida may serve as a marker for negative effects of exposure to xenobiotic contaminants.

Biodegradation of 3‐Chlorobenzoate as Affected by Rhizodeposition and Selected Carbon Substrates

AbstractThe plant rhizosphere has been hypothesized to generally increase the population numbers and activity of soil microorganisms that degrade various xenobiotic contaminants. However, the relative importance of increased C availability in the rhizosphere to microorganisms that directly metabolize xenobiotics as a C source for growth or that degrade xenobiotics through growth‐linked metabolism and cometabolism is not well understood. We hypothesized that when a xenobiotic can be used directly as a growth substrate, the rhizosphere would have relatively little influence on the catabolizer population since the substrate provides an independent nutritional niche. However, increased C levels in the rhizosphere might enhance the numbers of microorganisms that degrade the xenobiotic through cometabolism or metabolism that is linked to growth on other substrates. To further examine this hypothesis, experiments were conducted with soil containing indigneous microorganisms capable of degrading the model compound 3‐chlorobenzoate (3‐CB). The results showed degradation of 3‐CB in 1:1 soil/water slurries from ryegrass rhizosphere soil that had not been previously exposed to 3‐CB had a faster initial rate of 3‐CB degradation than nonrhizosphere soil. This rhizosphere effect could be simulated in nonrhizosphere soil using glucose, mannitol, or benzoate. A long‐term experiment further showed that the population size of microorganisms that degraded 3‐CB in the absence of supplemental C (catabolizers), and those that degraded 3‐CB in the presence of supplemental C, for example, via growth‐linked metabolism or cometabolism, were enriched by 40‐ and 250‐fold, respectively, in rhizosphere soil. In contrast, planted and nonplanted microcosms that were repeatedly exposed to 3‐CB over 24 wk were similarly enriched for 3‐CB degraders, which had a MPN of 4 × 108 g−1 soil. Our results suggest that under conditions where there is not constant exposure of the microbial population to 3‐CB as a C source, C provided by rhizodeposition may primarily enhance the population numbers of microorganisms that degrade 3‐CB by cometabolic or growth‐linked metabolism, and thereby promote rapid depletion of 3‐CB from soil during short term or low level exposure to the xenobiotic.

Solar photodegradation of xenobiotic contaminants in polluted well water

The photodegradation of xenobiotic contaminants in water samples taken from a heavily polluted well was studied using three photocatalytic treatments: TiO 2 and H 2O 2 (TI), Fe 3+ and H 2O 2 (T2) and TiO 2, Fe 3+ and H 2O 2 (T3). The water samples were concentrated by solvent extraction and analyzed by gas chromatograhy-mass spectrometry (GC-MS). The pollutants examined included a wide range of aliphatic and aromatic halogenated compounds, various types of herbicides, such as triazines, acetamides, bromouracil, halogenated hydroxy benzonitriles and urea herbicides, and also several groups of industrial organics, most of which were found to undergo photodegradation to less than 0.1 ppb. In a test of the time were appreciably degraded within 3.5 h by natural sunlight, but more complete detoxification required longer exposures. Long-chain fatty acid derivatives and phthalate esters were quite resistant to all three treatment methods.

Removing Trace‐Level Organic Pollutants in a Biological Filter

Laboratory‐scale biofilm reactors simulating a full‐scale nitrification filter were challenged with xenobiotic contaminants frequently encountered in water supplies. Phenol and mono‐ and dichlorophenols were removed immediately (by up to 92 percent), with increasing influent concentration reducing the percentage removal. Trichlorophenols were not biodegraded. Mono‐ and dichlorobenzenes were also removed (up to 81 percent), but an enzyme‐induction period of 8–20 h was required before biodegradation became significant. In many cases, feeding of an easily degraded organic substrate (acetate) increased removals of the xenobiotics by a relatively small amount. This result suggests that unidentified background organic material and soluble microbial products generated by nitrifying bacteria allow the accumulation of bacteria able to degrade a range of xenobiotic compounds.

Microbial activity in the terrestrial subsurface

Little is known about the layers under the earth's crust. Only in recent years have techniques for sampling the deeper subsurface been developed to permit investigation of the subsurface environment. Prevailing conditions in the subsurface habitat such as nutrient availability, soil composition, redox potential, permeability and a variety of other factors can influence the microflora that flourish in a given environment. Microbial diversity varies between geological formations, but in general sandy soils support growth better than soils rich in clay. Bacteria predominate in subsurface sediments, while eukaryotes constitute only 1–2% of the microorganisms. Recent investigations revealed that most uncontaminated subsurface soils support the growth of aerobic heteroorganotrophic bacteria, but obviously anaerobic microorganisms also exist in the deeper subsurface habitat. The microorganisms residing below the surface of the earth are capable of degrading both natural and xenobiotic contaminants and can thereby adapt to growth under polluted conditions.

Xenobiotic contaminants and the deleterious effects of fats

Conference Article| June 01 1989 Xenobiotic contaminants and the deleterious effects of fats R. SCHOENTAL R. SCHOENTAL 1Department of Pathology, Royal Veterinary College, University of London, Royal College Street, London NW1 OTU, England Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1989) 17 (3): 475–476. https://doi.org/10.1042/bst0170475 Article history Received: November 24 1988 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation R. SCHOENTAL; Xenobiotic contaminants and the deleterious effects of fats. Biochem Soc Trans 1 June 1989; 17 (3): 475–476. doi: https://doi.org/10.1042/bst0170475 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search This content is only available as a PDF. © 1989 Biochemical Society1989 Article PDF first page preview Close Modal You do not currently have access to this content.

Plant Biochemistry of Xenobiotics. Mineralization of Chloroaniline/Lignin Metabolites from Wheat by the White-Rot Fungus, Phanerochaete chrysosporium

Abstract The lignin metabolites formed in wheat plants from [ring-u-14C]-4-chloroaniline and -3,4-dichloroaniline were isolated by a Björkman-type procedure and characterized by gel permeation chromatography and chemical degradation. The isolated metabolite fractions were then incubated with the white-rot fungus, Phanerochaete chrysosporium. Mineralization to [14C]carbon dioxide occurred in high yields, about 65% of the initial radio­activity of the lignin-bound chloroanilines being trapped as CO2 after an incubation period of 32-33 days. The lignin metabolites with the 14C-label in the aromatic ring of the chloroanilines were mineralized as readily as a non-xenobiotic control lignin with a 14C-label in the aromatic ring of coniferyl alcohol. It is concluded that the white-rot fungus studied has an unusually high capacity for the removal of chloroanilines and possibly other xenobiotic contaminants from the environment.

Reproductive success, xenobiotic contaminants and hepatic mixed-function oxidase (MFO) activity in Platichthys stellatus populations from San Francisco Bay

To identify some specific effects of organic contaminants on fisheries in an urbanized estuary we compared the reproductive success of starry flounder from San Francisco Bay with concentrations of tissue contaminants and hepatic mixed-function oxidase (MFO) activity. We found significantly lower (P < 0·05) sediment concentrations of total identified polynuclear aromatic hydrocarbons (PAHs) in the less urbanized San Pablo Bay (SP) area (Fig. 1) than in the more urbanized central bay (CB) stations (Table 1). For flounder in early gametogenesis (August and September) the SP fish (n = 20) had significantly lower (P < 0·01) liver concentrations of Aroclor 1260 (0·34 ± 0·14 μg/g) than those at the CB stations: Berkeley (BK, n = 20, 1·6 ± 1·6 μg/g); Oakland (OK, n = 16, 2·3 ± 2·8 μg/g); and Alameda (AL, n = 4, 2·2 ± 1 μg/g). A similar pattern existed for DDT concentrations: SP = 0·2 ± 0·16 μg/g; BK = 0·1 ± 0·34 μg/g; OK = 0·4 ± 0·53 μg/g; and AL = 0·4 ± 0·33 μg/g. Total PAHs in livers were as follows: SP = 0·14 μg/g; BK = 2·6 μg/g; OK = 1·4 μg/g; and AL = 14 μg/g. Although gonad index, liver index, and presence of fin rot are inversely related to aryl hydrocarbon hydroxylase (AHH) activity, healthy fish in a similar reproductive state have lower AHH activities in the SP area. For example, in August and September, 1984, mean AHH activities were as follows: SP = 203 ± 89, and CB = 355 ± 200 pmol 3-OH-B[ a]P mg microsomal protein min. We found a log-linear relationship for AHH activity and its percent inhibition by 7,8-benzoflavone ( 10 −4 m ) and only a few fish from SP showed enhanced AHH activity after addition of 7,8-benzoflavone. This suggests that most of the starry flounder in San Francisco Bay are induced.