Arabidopsis thaliana plants acclimated to low dose rates of ultraviolet B radiation show specific changes in morphology and gene expression in the absence of stress symptoms

Ultraviolet B (UV-B) acclimation comprises complex and poorly understood changes in plant metabolism. The effects of chronic and ecologically relevant UV-B dose rates on Arabidopsis thaliana were determined. The UV-B acclimation process was studied by measuring radiation effects on morphology, physiology, biochemistry and gene expression. Chronic UV-B radiation did not affect photosynthesis or the expression of stress responsive genes, which indicated that the UV-acclimated plants were not stressed. UV-induced morphological changes in acclimated plants included decreased rosette diameter, decreased inflorescence height and increased numbers of flowering stems, indicating that chronic UV-B treatment caused a redistribution rather than a cessation of growth. Gene expression profiling indicated that UV-induced morphogenesis was associated with subtle changes in phytohormone (auxins, brassinosteroids and gibberellins) homeostasis and the cell wall. Based on the comparison of gene expression profiles, it is concluded that acclimation to low, chronic dose rates of UV-B is distinct from that to acute, stress-inducing UV-B dose rates. Hence, UV-B-induced morphogenesis is functionally uncoupled from stress responses.

Occurrence of perfluorooctane sulfonate and other perfluorinated alkylated substances in harbor porpoises from the Black Sea

Perfluorooctane sulfonate (PFOS) and other perfluorinated alkylated substances (PFAS) were determined in liver, kidney, muscle, brain, and blubber samples of 31 harbor porpoises (Phocoena phocoena relicta) of different age and sex stranded along the Ukrainian coast of the Black Sea. In all individuals and in all tissues, PFOS was the predominant PFAS, accounting for on average 90% of the measured PFAS load. PFOS concentrations were the highest in liver (327+/-351 ng/g wet wt) and kidney (147 +/-262 ng/g wet wt) tissue, and lower in blubber (18+/-8 ng/g wet wt), muscle (41+/-50 ng/g wet wt), and brain (24 +/-23 ng/g wetwt). No significant differences could be determined between males and females, nor between juvenile and adult animals (p > 0.05). Perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, and perfluorododecanoic acid could be detected in liver tissue of approximately 25% of the individuals. Perfluorobutane sulfonate, perfluorobutanoic acid, and perfluorooctanoic acid were not detected in any of the porpoise livers. Although we investigated a potential intraspecies segregation according to the source of prey, using stable isotopes, no statistically significant correlation between PFOS concentrations and stable isotopes could be determined. It is, however, noteworthy that the contamination by PFOS in the Black Sea harbor porpoises is comparable to levels found in porpoises from the German Baltic Sea and from coastal areas near Denmark and, therefore, might pose a threat to this population.

Effects of the antidepressant mianserin in zebrafish: molecular markers of endocrine disruption

Due to their environmental occurrence and intrinsic biological activity, human pharmaceuticals have received increasing attention from environmental and health agencies. Of particular, ecotoxicological concern are drugs that affect nervous- and endocrine-systems. Zebrafish genome-wide oligo arrays are used to collect mechanistic information on mianserin-induced changes in gene expression in zebrafish. Gene expression analysis in brain and gonad tissue clearly demonstrated the estrogenic activity of mianserin and its potency to disrupt normal endocrine (estrogenic) signaling, based on induction of molecular biomarkers of estrogenicity (e.g., vitellogenin1 and zona pellucida proteins). The possible mechanism underlying this estrogenic activity of mianserin is disturbance of the Hypothalamo-Pituitary-Gonadal (HPG) axis by direct interference of mianserin with the serotonergic and adrenergic systems in the brain of zebrafish. Taking into account the importance of the HPG-axis, and considering the concept of 'critical window of exposure', our results reveal the importance for more elaborate testing of endocrine disruptive effects of aquatic antidepressants at different lifestages and during longer exposure periods (e.g., life cycle studies). Although there is a low concordance between the gene expression results in this study and previous cDNA microarray hybridizations, the global mechanistic expression patterns are similar in both platforms. This argues in favor of pathway-driven analysis of gene expression results compared to gene-per-gene analysis.

Effect of copper exposure on gene expression profiles in Chlamydomonas reinhardtii based on microarray analysis

Copper is a naturally occurring trace metal with toxic properties for man and environment. It is assumed that toxicity is primarily caused by oxidative damage, generated through the production of reactive oxygen species. Copper is, however, also an essential element, which means trace amounts are necessary for biological processes to function properly. Organisms are therefore presented with the challenging problem of maintaining copper concentrations within a well-defined range to avoid stress. We exposed the green alga Chlamydomonas reinhardtii to different copper concentrations and used microarray analysis to investigate the changes in mRNA abundances and to obtain an image of the molecular mechanisms underlying copper homeostasis. The results confirm and extend upon previous findings showing that in the case of lower copper concentrations there is a change in levels of mRNA coding for alternative polypeptides which can take over the function of certain copper containing molecules so as to compensate for the lack of copper. In the case of copper toxicity, there is a strong upregulation of transcripts encoding enzymes involved in oxidative stress defense mechanisms. In both cases, there were significant changes in expression levels of transcripts coding for enzymes involved in several metabolic pathways (photosynthesis, pentose phosphate pathway, glycolysis, gluconeogenesis), in general stress response (heat shock proteins) and in intracellular proteolysis (lysosomal enzymes, proteasome components).

Genotoxicity in wood mice (Apodemus sylvaticus) along a pollution gradient: exposure-, age-, and gender-related effects

We investigated the effects of environmental pollution on genetic damage in wood mice (Apodemus sylvaticus) by means of the comet assay, with special attention to the role of age and gender as potential confounding variables. The present study was carried out at four sites along a pollution gradient in the vicinity of Antwerp (Belgium), with a nonferrous smelter as the main pollution source. We measured the concentration of heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Pb, and Zn) in mouse liver and kidney and the concentration of organochlorine compounds (polychlorinated biphenyls and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) in mouse muscle tissue to assess individual exposure. Cadmium exposure was very high at the sites closest to the smelter, and exposure to this metal decreased with increasing distance from the smelter. Exposure to the other pollutants was low to moderate at the different sites. Genetic damage was higher in mice from populations in the vicinity of the nonferrous smelter compared with that in the control populations. A significant increase in genetic damage with age was observed at the most polluted sites, but not at the control sites. Genetic damage was higher in male mice than in female mice at the most polluted site, but not at the other areas. Yet, no obvious relationship was found between individual pollutant levels and individual genetic damage levels. We conclude that the comet assay can be used to compare genotoxicity at the population level if the confounding variables of gender and age are taken into account. However, its use for individual health risk assessment remains questionable.

Tracing of labile zinc in live fish hepatocytes using FluoZin-3

Intracellular zinc levels are homeostatically regulated and although most is bound, a pool of labile Zn(II) is present in cells. We show here that the zinc probe FluoZin-3 is useful to monitor zinc fluxes during fluorescent imaging of the trout hepatic cell line D11. Nuclei and bulk cytosol appeared to lack detectable labile zinc, while the punctuate staining pattern colocalized with a lysosome-specific probe. Applying extracellular zinc alone resulted in vesicular sequestration of the metal ion. Together with Na-pyrithione a delayed and toxic rise in cellular fluorescence was triggered. When using another ionophore, 4-Br A23187, a zinc buffering effect of the vesicular pools was evident. Secondly, N-ethylmaleimide induced a homogeneous fluorescence rise, which was strongly enhanced by addition of Zn-pyrithione and disappeared after TPEN washing. This suggests the involvement of thiol residues in controlling available cytosolic zinc. Our observations have implications for the interpretation of calculated intracellular Zn2+ concentrations.

Non-destructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): II. Hair and spines as indicators of endogenous metal and As concentrations

The role of hair and spines of the European hedgehog as non-destructive monitoring tools of metal (Ag, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn) and As pollution in terrestrial ecosystems was investigated. Our results showed that mean pollution levels of a random sample of hedgehogs in Flanders are low to moderate. Yet, individual hedgehogs may be at risk for metal toxicity. Tissue distribution analyses (hair, spines, liver, kidney, muscle and fat tissue) indicated that metals and As may reach considerable concentrations in external tissues, such as hair and spines. Positive relationships were observed between concentrations in hair and those in liver, kidney and muscle for Al, Co, Cr, Cu, and Pb (0.43 < r < 0.85). Spine concentrations were positively related to liver, kidney and muscle concentrations for Cd, Co, Cr, Cu and Pb (0.37 < r < 0.62). Hair Ag, As, Fe and Zn and spine Ag, Al, As and Fe were related to metal concentrations in one or two of the investigated internal tissues (0.31 < r < 0.45). The regression models presented here may be used to predict metal and As concentrations in internal tissues of hedgehogs when concentrations in hair or spines are available. The present study demonstrated the possibility of using hair and spines for non-destructive monitoring of metal and As pollution in hedgehogs.

Cadmium and zinc induction of ZnT-1 mRNA in an established carp cell line

The cDNA of a zinc transporter-1 (ZnT-1) gene was cloned from an established cell line derived from common carp (Cyprinus carpio) using rapid amplification of cDNA ends (RACE). Using real-time quantitative PCR, we showed that both zinc (Zn) and cadmium (Cd) transiently upregulate ZnT-1 mRNA to comparable levels. The loosely bound cellular Zn pool, as estimated using the Zn-specific probe FluoZin-3, was increased threefold after exposure to 250 microM ZnCl(2). Correspondingly, the ZnT-1 mRNA level at 24 h was induced about fivefold, reflecting the need for more zinc export capacity. Total cellular zinc levels were not different from the controls after 72 h of exposure to 10, 50, or 250 microM ZnCl(2). A loss of total cellular Zn but little labile zinc changes were observed with up to 25 microM Cd. At 72 h, the total Zn was partially restored to the control levels, only 1 microM Cd allowed for a full recovery. Downregulation of ZnT-1 mRNA and partial loss of loosely bound Zn were observed with 50 microM Cd. Our results clearly show that although Zn and Cd can both regulate Zn export in EPC cells, the effects on the cellular Zn pools are quite different.

Ecological impact assessment of metallurgic effluents using in situ biomarker assays

An ecological impact study was performed based on in situ biomarker assays with the waterflea Daphnia magna. The effects of metallurgic effluents on the energy metabolism, anti-oxidative metabolism and DNA damage were assessed in caged daphnids during a 4-week study. In situ survival and reproduction studies demonstrated a clear impact on these parameters in organisms exposed in the most polluted areas. At the downstream--sublethal--zone the organisms were disturbed within their tolerance limits, resulting in alterations of their energy metabolism. These data suggest an acclimation hypothesis, which was tested through the analysis of the energy metabolism of resident species: isopods and amphipods. These organisms had shifted to a decrease in their overall energy metabolism compared to the upstream region. This change in some biochemical processes suggests a selective advantage to cope with the prevailing environmental conditions. In addition, we found clear genotoxic effects caused by the industrial discharges that might correlate with a reduction in (long-term) survival.

Metal blood levels and hematological characteristics in wood mice (Apodemus sylvaticus L.) along a metal pollution gradient

The present study evaluated whether blood could be used as a nondestructive tool for monitoring metal exposure and related hematological effects in wood mice (Apodemus sylvaticus L.) living along a metal pollution gradient. Soil concentrations of arsenic, cadmium, copper, lead, silver, and zinc decreased with distance from the emission source. Blood levels of cadmium and lead differed significantly among sites, whereas those of the other metals did not. Blood levels of cadmium and lead correlated with soil concentrations of cadmium and lead, respectively. No such significant relationships were found for the other measured metals. Hematocrit levels decreased in wood mice from the most polluted site (45.96% +/- 0.53% [mean +/- standard error]) compared to the reference site (48.04% +/- 0.47%). A negative correlation between hematocrit and blood levels of cadmium and lead was found. Erythrocyte count, leukocyte count, hemoglobin concentration, mean corpuscular hemoglobin (average wt of hemoglobin in a red blood cell in pg), and lysozyme activity did not differ among study sites. Mean corpuscular volume (average volume of a red blood cell in microm3) and mean corpuscular hemoglobin concentration (average proportion of hemoglobin in a red blood cell as a %) differed among study sites but showed no relationship with metal exposure. We conclude that whole blood from mice can be used for nondestructive monitoring of the exposure to nonessential metals under natural conditions. The present results indicate that decreased hematocrit levels may be an early warning signal for a negative impact of metal exposure on the oxygen-transport capacity of blood in wood mice in their natural environment.

Nondestructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): III. Hair as an indicator of endogenous organochlorine compound concentrations

Concentrations of organochlorine persistent pollutants were investigated in tissues of the European hedgehog (Erinaceus europaeus). Road kills and carcasses from wildlife rescue centers were used to characterize organochlorine compound tissue distribution and tissue profile dissimilarities (hair, liver, kidney, muscle, and adipose tissue). The most important contaminants were polychlorinated biphenyls (PCBs), chlordanes (CHLs), and DDTs, with median concentrations of 75, 5.1, and 1.4 ng/g liver wet weight, respectively. Median levels for the remaining compounds-hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and octachlorostyrene-were less than 0.5 ng/g liver wet weight. Compared to results with other mammalian wildlife, the present results indicate that hedgehogs may accumulate considerable concentrations of organochlorine compounds. Polychlorinated biphenyls and HCB preferably accumulated in liver and muscle tissue. Concentrations of DDTs and HCHs were highest in muscle tissue and hair, respectively. Octachlorostyrene and CHL levels were predominant in liver. The observed positive relationships between concentrations in hair and internal tissues for PCBs, DDTs, HCB, HCHs, and CHLs (0.49 < r < 0.91) and for several individual PCB, DDT, and CHL compounds (0.31 < r < 0.76) indicate the usefulness of hair as a biomonitoring tool of organochlorine compounds. Multivariate profile analyses revealed a higher dominance of less-persistent compounds (p,p'-DDT, alpha-HCH, and PCBs 95, 101, and 149) in hair compared to internal tissues. The present study demonstrates the suitability of hedgehog hair as a nondestructive biomonitoring tool regarding pollution with organochlorine compounds and the promising role of the hedgehog as a mammalian indicator species of pollution in terrestrial environments.

Estrogen-like properties of fluorotelomer alcohols as revealed by mcf-7 breast cancer cell proliferation

We investigated estrogen-like properties of five perfluorinated compounds using a combination of three in vitro assays. By means of an E-screen assay, we detected the proliferation-promoting capacity of the fluorotelomer alcohols 1H,1H,2H,2H-perfluorooctan-1-ol (6:2 FTOH) and 1H,1H,2H,2H-perfluoro-decan-1-ol (8:2 FTOH). The more widely environmentally distributed compounds perfluoro-1-octane sulfonate, perfluorooctanoic acid, and perfluorononanoic acid did not seem to possess this hormone-dependent proliferation capacity. We investigated cell cycle dynamics using flow cytometric analyses of the DNA content of the nuclei of MCF-7 breast cancer cells. Exposure to both fluorotelomer alcohols stimulated resting MCF-7 cells to reenter the synthesis phase (S-phase) of the cell cycle. After only 24 hr of treatment, we observed significant increases in the percentage of cells in the S-phase. In order to further investigate the resemblance of the newly detected xenoestrogens to the reference compound 17beta-estradiol (E2), gene expression of a number of estrogen-responsive genes was analyzed by real-time polymerase chain reaction. With E2, as well as 4-nonylphenol and the fluorotelomer alcohols, we observed up-regulation of trefoil factor 1, progesterone receptor, and PDZK1 and down-regulation of ERBB2 gene expression. We observed small but relevant up-regulation of the estrogen receptor as a consequence of exposures to 6:2 FTOH or 8:2 FTOH. The latter finding suggests an alternative mode of action of the fluorotelomer alcohols compared with that of E2. This study clearly underlines the need for future in vivo testing for specific endocrine-related end points.

Evaluation of biochemical effects related to perfluorooctane sulfonic acid exposure in organohalogen-contaminated great tit (Parus major) and blue tit (Parus caeruleus) nestlings

A perfluorooctane sulfonic acid (PFOS) biomonitoring survey was conducted on great tit (Parus major) and blue tit (Parus caeruleus) nestlings from Blokkersdijk, a bird reserve in the proximity of a fluorochemical plant in Antwerp (Belgium) and Fort IV, a control area. PFOS, together with 11 organochlorine pesticides, 20 polychlorinated biphenyl congeners and 7 polybrominated diphenyl ethers were measured in liver tissue. The hepatic PFOS concentrations at Blokkersdijk (86-2788 and 317-3322 ng/g wet weight (ww) for great and blue tit, respectively) were among the highest ever measured and were significantly higher than at the control area (17-206 and 69-514 ng/g ww for great and blue tit, respectively). The hepatic PFOS concentration was species- and sex-independent and correlated significantly and positively with the serum alanine aminotransferase activity and negatively with the serum cholesterol and triglyceride levels in both species but did not correlate with condition or serum protein concentration. In the great tit, a significant positive correlation was observed between the liver PFOS concentration and the relative liver weight. In the blue tit, the hepatic PFOS concentration correlated positively and significantly with hematocrite values. None of the investigated organohalogen pollutants except for PFOS were suggested to be involved in the observed biological alterations.

Tissue distribution of perfluorinated chemicals in harbor seals (Phoca vitulina) from the Dutch Wadden Sea

Perfluorinated acids (PFAs) are today widely distributed in the environment, even in remote arctic areas. Recently, perfluorooctane sulfonate (PFOS) has been identified in marine mammals all over the world, but information on the compound-specific tissue distribution remains scarce. Furthermore, although longer perfluorinated carboxylic acids (PFCAs) are used in industry and were shown to cause severe toxic effects, still little is known on potential sources or their widespread distribution. In this study, we report for the first time on levels of longer chain PFCAs, together with some short chain PFAs, perfluorobutane sulfonate (PFBS) and perfluorobutanoate (PFBA), in liver, kidney, blubber, muscle, and spleen tissues of harbor seals (Phoca vitulina) from the Dutch Wadden Sea. PFOS was the predominant compound in all seal samples measured (ranging from 89 to 2724 ng/g wet weight); however, large variations between tissues were monitored. Although these are preliminary results, it is, to our knowledge, the first time that PFBS could be found at detectable concentrations (2.3 +/- 0.7 ng/g w wt) in environmental samples. PFBS was only detected in spleen tissue. PFCA levels were much lower than PFOS concentrations. The dominant PFCA in all tissues was PFNA (perfluorononanoic acid), and concentrations generally decreased in tissues for all other PFCA homologues with increasing chain length. No clear relationship between PFOS levels in liver and kidney was observed. Furthermore, hepatic PFDA (perfluorodecanoic acid) levels increased with increasing body length, but in kidney tissue, PFDA levels showed an inverse relationship with increasing body length. These data suggest large differences in tissue distribution and accumulation patterns of perfluorinated compounds in marine organisms.

Nondestructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): I. Relationships between concentrations of metals and arsenic in hair, spines, and soil

Conventional metal exposure assessment in terrestrial mammals is generally based on organ analyses of sacrificed animals. Few studies on mammals use nondestructive methodologies despite the growing ethical concern over the use of destructive sampling. Nondestructive methods involve minimal stress to populations and permit successive biomonitoring of the same populations and individuals. In the present study we assessed metal exposure of hedgehogs (Erinaceus europaeus) by investigating relationships between concentrations of metals (Ag, Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) and As in soil samples and in hair and spines of hedgehogs. Samples were collected in seven study sites along a metal pollution gradient, characterized by decreasing total soil Ag, As, Cd, Cu, Ni, and Pb concentrations with increasing distance from a nonferrous metallurgic factory. For a number of elements, soil contamination was related both to distance to the smelter and to habitat. Soil concentrations were positively related to levels in hair and spines for Ag, As, Cd, and Pb and thus to hedgehog exposure. Metal concentrations in soil did not relate to metal concentrations in hair and spines for essential elements (e.g., Cu, Fe, Mn, Ni, and Zn), except Co in hair and soil. Our results demonstrate that, at least for nonessential elements, concentrations in soils can be used to predict contamination of these elements in hedgehogs or vice versa. Furthermore, hedgehog exposure increased toward the smelter and was higher for hedgehogs foraging in grasslands than for animals foraging in the forest. Moreover, we believe that hair and spines are promising tools in terrestrial wildlife exposure assessment studies of metals and As.

Perfluorooctane sulfonic acid and organohalogen pollutants in liver of three freshwater fish species in Flanders (Belgium): relationships with biochemical and organismal effects

A perfluorooctane sulfonic acid (PFOS) assessment was conducted on gibel carp (Carassius auratus gibelio), carp (Cyprinus carpio), and eel (Anguilla anguilla) in Flanders (Belgium). The liver PFOS concentrations in fish from the Ieperlee canal (Boezinge, 250-9031 ng/g wet weight, respectively) and the Blokkersdijk pond (Antwerp, 633-1822 ng/g wet weight) were higher than at the Zuun basin (Sint-Pieters-Leeuw, 11.2-162 ng/g wet weight) and among the highest in feral fish worldwide. Eel from the Oude Maas pond (Dilsen-Stokkem) and Watersportbaan basin (Ghent) had PFOS concentrations ranging between 212 and 857 ng/g wet weight. The hepatic PFOS concentration was significantly and positively related with the serum alanine aminotransferase activity, and negatively with the serum protein content in eel and carp. The hepatic PFOS concentration in carp correlated significantly and negatively with the serum electrolyte concentrations whereas a significant positive relation was found with the hematocrit in eel. Although 13 organochlorine pesticides, 22 polychlorinated biphenyl (PCB) congeners and 7 polybrominated diphenyl ethers (PBDEs) were also measured in the liver tissue, only PCB 28, PCB 74, gamma-hexachlorocyclohexane (gamma-HCH) and hexachlorobenzene (HCB) were suggested to contribute to the observed serological alterations in eel.

Hair as an indicator of endogenous tissue levels of brominated flame retardants in mammals

Few data are available on brominated flame retardants (BFRs) in terrestrial mammalian wildlife. Moreover, the use of hair in nondestructive monitoring of BFRs in mammals or humans has not been investigated. In the present study, concentrations of polybrominated diphenyl ethers (PBDEs) and brominated biphenyl 153 (BB 153) were analyzed in tissues of the European hedgehog Erinaceus europaeus. Road kills and carcasses from wildlife rescue centers were used to investigate relationships between concentrations of BFRs in hair and internal tissues, BFR tissue distribution (hair, liver, kidney, muscle, and adipose tissue), and PBDE congener tissue pattern dissimilarities. Liver concentrations of PBDEs and BB 153 were in the ranges 1-1178 and 0-2.5 ng/g of liver wet weight, respectively. PBDEs were predominant in adipose tissue and liver, while accumulation of BB 153 was tissue independent. The less persistent compound BDE 99 was more dominant in hair than in internal tissues. We observed positive relationships between BFR levels in hair and internal tissues for sum PBDEs and BDE 47 (0.37 < r < 0.78). The present study demonstrated that hair is a suitable indicator of PBDE exposure in terrestrial mammals which can be used in nondestructive monitoring schemes.

Development and application of a brain-specific cDNA microarray for effect evaluation of neuro-active pharmaceuticals in zebrafish (Danio rerio)

The environmental fate and ecotoxicological effect of pharmaceuticals are poorly understood, and standardized tests to detect and evaluate their potential effects in the environment are not available. We developed a zebrafish brain-specific microarray containing 682 neurologically relevant cDNA-fragments. To investigate the applicability of this microarray for studying neurotoxic modes-of-action and impact assessment of neuro-active pharmaceuticals in zebrafish, chlorpromazine was used as a model compound. After exposure to chlorpromazine (75 microg/L) for 2, 4, 14 and 28 days or control treatment RNA was extracted from brains of males and females. Fluorescently labeled cDNA was prepared and hybridized to the custom microarray. In total, 56 genes were differentially expressed in brains of male and/or female zebrafish, of which most genes were down-regulated. A clear difference in response to chlorpromazine exposure between males and females was observed with exposure time as well as in functional classes of affected genes. The presented study is one of the first reports on molecular effects of human neuro-active pharmaceuticals in aquatic non-target organisms. This new genomic tool successfully detected gene expression effects of exposure to chlorpromazine in the brain of zebrafish. Reported gene expression effects are found to be consistent with literature data for other laboratory animals.

New metallothionein mRNAs in Gobio gobio reveal at least three gene duplication events in cyprinid metallothionein evolution

This paper reports the identification and analysis of the primary structure of three novel metallothionein cDNA sequences in the gudgeon, Gobio gobio (Cyprinidae). Two different 180 bp coding regions were identified, resulting in two MT isoforms differing in one amino acid. The primary structure of the amino acid sequence was compared to other cyprinid MT sequences. Furthermore, two differently sized cDNAs were discovered in one of the two transcripts. We present a phylogenetic comparison of our sequences to other, previously published cyprinid MT gene sequences. Our analysis reveals an unexpected complexity in cyprinid MT evolution, with at least three gene duplication events. Differences and homologies between the evolution of cyprinid MT genes are compared to other teleost families. Finally, possible implications for metallothionein classification are discussed.

Tissue-specific Cu bioaccumulation patterns and differences in sensitivity to waterborne Cu in three freshwater fish: rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio), and gibel carp (Carassius auratus gibelio)

Rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio) and gibel carp (Carassius auratus gibelio) were exposed to copper (1-20 microM) in softened Antwerp City tap water at pH 7.3 +/- 0.1 and with a water hardness of 292.4 +/- 8.1 mg/L CaCO(3) (Ca 100.8 +/- 3.0 mg/L; Mg 11.0 +/- 0.2 mg/L). LC50s (96 h) were determined and copper accumulation in gills, liver, and kidney assessed over a 10-day period. Rainbow trout (96 h LC50: 3.3 microM/210 microg/L) were three times more sensitive to Cu exposure than common carp (96 h LC50: 10.4 microM/661 microg/L) and almost seven times more sensitive than gibel carp (96 h LC50: 22.0 microM/1398 microg/L). After 96 h, the incipient lethal level (ILL) was reached for common carp, and by the end of the experiment (>120 h) also for rainbow trout. The ILL was never reached for gibel carp. Survival analysis confirmed the differences in sensitivity shown by the 96 h LC50 values. At 1 microM Cu, the relative risk to die was six to seven times greater for rainbow trout as for common or gibel carp, respectively, while it was 9000 and 19,000 times greater at 5 microM Cu. Only the environmental Cu concentrations contributed significantly (P < 0.001) to the Time-To-Death (TTD). Tissue Cu concentrations did not relate to TTD. Among species, a clear difference in metal handling was apparent, with high liver residues and liver accumulation rates for the most sensitive species, the rainbow trout, and lower liver but higher kidney residues and kidney accumulation rates for the most resistant species, the gibel carp. Gill concentrations and accumulation rates were lowest in the sensitive rainbow trout.

Immunotoxicology in wood mice along a heavy metal pollution gradient

We carried out an immunotoxicological field study of wood mice in three populations along a heavy metal pollution gradient. Heavy metal concentrations in liver tissue indicated that exposure to silver, arsenic, cadmium, cobalt and lead decreased with increasing distance from a non-ferrous smelter. Host resistance to the endoparasite Heligmosomoides polygyrus decreased with increasing exposure, while the abundance of tick larvae and the nematode Syphacia stroma was unrelated to heavy metal exposure. Spleen mass was increased at the intermediate and the most polluted sites and was positively correlated with the number of H. polygyrus and tick larvae. Proportion of early apoptotic leukocytes increased towards the smelter and was positively related to cadmium exposure. Red and white blood cell counts and lysozyme activity showed no relationship with metal exposure. All together, our observations suggest negative effects of heavy metal exposure on the immune function of wood mice under field conditions.

Biochemical effect evaluation of perfluorooctane sulfonic acid-contaminated wood mice (Apodemus sylvaticus)

Wood mice (Apodemus sylvaticus) were captured at Blokkersdijk, a nature reserve in the immediate vicinity of a fluorochemical plant in Antwerp, Belgium, and at Galgenweel, 3 kilometers farther away. The liver perfluorooctane sulfonic acid (PFOS) concentrations in the Blokkersdijk mice were extremely high (0.47-178.55 micro g/g wet weight). Perfluorononanoic, perfluorodecanoic, perfluoroundecanoic, and perfluorododecanoic acids were found sporadically in the liver tissue of the Blokkersdijk mice. The liver PFOS concentrations at Galgenweel were significantly lower than those at Blokkersdijk (0.14-1.11 micro g/g wet weight). Further results suggest sex independence of the liver PFOS levels, increased levels of PFOS bioaccumulation in older mice, and maternal PFOS transfer to the young. Several liver end points were significantly elevated in the Blokkersdijk mice: liver weight, relative liver weight, peroxisomal beta-oxidation activity, microsomal lipid peroxidation level, and mitochondrial fraction protein content. For the mitochondrial fraction catalase activity, no significant difference between locations was found. The liver weight, relative liver weight, and liver microsomal lipid peroxidation level increased significantly with the liver PFOS concentration. No indications for PFOS-mediated effects on the serum triglyceride, cholesterol, or potassium levels were obtained. The liver PFOS concentration was negatively related to the serum alanine aminotransferase activity.

Binding of perfluorinated fatty acids to serum proteins

Perfluorooctane sulfonic acid (PFOS) accumulates in the liver and blood of exposed organisms. The potential for these surfactant molecules to interfere with hormone/protein interactions in blood is of concern given the importance of these interactions. The PFOS binding to serum proteins was investigated by assessing its ability to displace a variety of steroid hormones from specific binding proteins in the serum of birds and fishes. Perfluorooctane sulfonic acid had only a weak ability to displace estrogen or testosterone from carp serum steroid binding proteins. Displacement of cortisone in avian sera occurred at relatively low PFOS concentrations. Corticosterone displacement potency increased with chain length, and sulfonic acids were more potent than carboxylic acids. The PFOS concentrations estimated to cause these effects were 320 microM or greater, equivalent to serum concentrations greater than 160 mg/L. Using mass spectrometry and direct in vitro binding assays, PFOS was demonstrated to bind strongly to bovine serum albumin (BSA) in a 1:1 stoichiometric ratio. It appears that PFOS in serum is in general bound to albumins. Concentrations of PFOS required to saturate albumin would be in excess of 50 to 100 mg/L. Based on current environmental concentrations, it is unlikely that PFOS would cause displacement of hormones from serum proteins in wildlife.