J.M. Everaarts

Koninklijk Nederlands Instituut voor Onderzoek der Zee - NIOZ, Burg, North Holland, Netherlands

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Publications (51)98.24 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Recent surveys in the southern and central North Sea and the Dutch Wadden Sea revealed that the whelk Buccinun undarum L. can no longer be found in areas where whelks were abundant twenty or more years ago. The decline of whelk populations tends to coincide with areas of various, intense human activities, which may cause either pollution or physical damage. Potential causes for the decline of whelks from the southern North Sea and coastal areas are discussed and considered in view of North Sea ecology and protective policies for the North Sea.
    No preview · Article · May 2008 · Marine Ecology
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    ABSTRACT: Primary hepatocytes of the rainbow trout (Oncorhynchus mykiss), flounder (Platychthis flesus), dab (Limanda limanda) and lemon sole (Microstomus kitt) were exposed to 3,3'4,4'5 pentachlorobiphenyl (PCB 126) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for two days. This resulted in a dose-dependent induction of cytochrome P4501A (CYP1A) activity, measured as ethoxyresorufin O-deethylase (EROD), or methoxyresorufin O-deethylase (MROD) activity. In all species, a linear relationship was observed between EROD and MROD activities, suggesting that the same CYP1A enzyme metabolizes the two alkoxy-resorufin substrates. Exposures of hepatocytes of flounder or dab to TCDD, resulted in a 59-fold and 8.2-fold induction of EROD activity, respectively. This did not concur with a change in the in vitro testosterone hydroxylation profiles of both species. These and other in vitro data indicate that TCDD exposure does not influence monooxygenase activities involved in testosterone hydroxylation. Furthermore, CYP1A is of minor importance for testosterone hydroxylation in these fish species.
    Full-text · Article · Feb 2002 · Chemosphere
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    ABSTRACT: Polycyclic aromatic hydrocarbons (PAHs) are abundant pollutants, and many PAHs are carcinogenic, but only after metabolic activation. Benzo[a]pyrene (BaP) is among the most carcinogenic PAHs. The dose and time response of two enzymes involved in BaP metabolism and the amounts of BaP metabolites excreted into the bile were evaluated in an experiment with dab (Limanda limanda). Ninety dab were exposed orally to one of five doses of BaP (0, 0.08, 0.4, 2, or 10 mg/kg) and sampled at 3, 6, or 12 d after exposure. None of the doses studied caused significant induction of either microsomal ethoxyresorufin-O-deethylase (EROD). which reflects cytochrome P450 1A (CYP1A) activity, or cytosolic glutathione-S-transferase activity (GST). Concentrations of biliary BaP metabolites significantly increased with dose and significantly decreased with time after exposure. It is concluded that biliary BaP metabolites provide a much more sensitive method than EROD (CYP1A) or GST activity to monitor recent exposure to PAHs in dab.
    No preview · Article · Aug 2001 · Environmental Toxicology and Chemistry
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    ABSTRACT: During two North Sea field trips in March 1995 and September 1996 sea stars, Asterias rubens, were collected at various stations along pollution gradients in order to study the relation between biochemical markers and levels of accumulated contaminants. Biomarkers measured were: cytochrome P450 level, benzo[a]pyrene hydroxylase (BPH) activity, acetylcholinesterase (AChE) activity and DNA integrity. Accumulation levels of heavy metals, polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs) in the pyloric caeca of sea stars indicate different pollution gradients, influenced by rivers in The Netherlands, UK and Germany. For some contaminants, especially PAHs, relatively high levels were found in the central part of the North Sea (Dogger Bank). On the basis of multivariate statistics, stations near the mouth of the Elbe and the Rhine/Meuse were shown to have different patterns of biomarker responses. Sea stars from stations in coastal zones showed relatively high levels of cytochrome P450 and 'P418', another haemoprotein that is present in most marine invertebrates. The station nearest to the Elbe Estuary showed the lowest BPH and AChE activity. DNA integrity was lower especially in stations near the Dutch coast and in a station near the Tees/Tyne estuaries. Using these biomarkers as early warning signals of exposure and/or adverse effects, this type of monitoring can be used also in the future to study the spatial and temporal trends in the quality of coastal waters.
    No preview · Article · Jun 2001 · Marine Environmental Research
  • P.J. den Besten · J.F. Postma · S. de Valk · M. Dubbeldam · J.M. Everaarts

    No preview · Chapter · Jan 2001
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    ABSTRACT: Two experiments were performed to study the interaction between benzo[a]pyrene (BaP) and the planar, dioxin-like PCB congener 3,3',4,4',5-pentachlorobiphenyl (CB 126) in the flatfish dab (Limanda limanda). The first experiment involved four groups. Group I was treated with 10 µg/kg CB 126, group II was treated with 2 mg/kg BaP, group III was first treated with 10 µg/kg CB 126 and exposed to 2 mg/kg BaP 6 days later, and group IV was a control group. The second experiment was similar, except that the BaP dosage level was increased to 50 mg/kg. Pre-treatment with 10 µg/kg of CB 126 always caused the induction of hepatic cytochrome P450 1A (CYP1A), as measured by significant increases of the model reaction 7-ethoxyresorufin-O-deethylase (EROD) in microsomal preparations. Treatment of dab with BaP caused a significant EROD induction at the 50 mg/kg, but not at the 2 mg/kg level. Concurrent with EROD induction by either CB 126 or 50 mg/kg BaP, was a significant change in the biliary metabolite pattern in favour of 1-hydroxybenzo[a]pyrene and 3-hydroxybenzo[a]pyrene and towards a lower fraction of the procarcinogen BaP-7,8-dihydrodiol (7,8-DIOL). Pre-treatment with CB 126 did not cause an increase of hepatic BaP DNA adducts formed after treatment with either 2 or 50 mg/kg BaP. Glutathione S-transferase (GST) activities remained also unaffected by any of the treatments. The results of this study suggest that the pattern of BaP metabolites in bile depends on the level of CYP1A induction. Moreover, the concurrence of a potent CYP1A inducer and BaP does not necessarily lead to an increase in DNA adduct levels in liver tissue. The observation that the level of 7,8-DIOL is decreased despite a higher (CYP1A mediated) EROD activity explains, at least in part, the lack of induction of DNA adducts.
    No preview · Article · Nov 2000 · Aquatic toxicology (Amsterdam, Netherlands)
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    ABSTRACT: Two experiments were performed to study the interaction between benzo[a]pyrene (BaP) and the planar, dioxin-like PCB congener 3,3′,4,4′,5-pentachlorobiphenyl (CB 126) in the flatfish dab (Limanda limanda). The first experiment involved four groups. Group I was treated with 10 μg/kg CB 126, group II was treated with 2 mg/kg BaP, group III was first treated with 10 μg/kg CB 126 and exposed to 2 mg/kg BaP 6 days later, and group IV was a control group. The second experiment was similar, except that the BaP dosage level was increased to 50 mg/kg. Pre-treatment with 10 μg/kg of CB 126 always caused the induction of hepatic cytochrome P450 1A (CYP1A), as measured by significant increases of the model reaction 7-ethoxyresorufin-O-deethylase (EROD) in microsomal preparations. Treatment of dab with BaP caused a significant EROD induction at the 50 mg/kg, but not at the 2 mg/kg level. Concurrent with EROD induction by either CB 126 or 50 mg/kg BaP, was a significant change in the biliary metabolite pattern in favour of 1-hydroxybenzo[a]pyrene and 3-hydroxybenzo[a]pyrene and towards a lower fraction of the procarcinogen BaP-7,8-dihydrodiol (7,8-DIOL). Pre-treatment with CB 126 did not cause an increase of hepatic BaP DNA adducts formed after treatment with either 2 or 50 mg/kg BaP. Glutathione S-transferase (GST) activities remained also unaffected by any of the treatments. The results of this study suggest that the pattern of BaP metabolites in bile depends on the level of CYP1A induction. Moreover, the concurrence of a potent CYP1A inducer and BaP does not necessarily lead to an increase in DNA adduct levels in liver tissue. The observation that the level of 7,8-DIOL is decreased despite a higher (CYP1A mediated) EROD activity explains, at least in part, the lack of induction of DNA adducts.
    No preview · Article · Oct 2000
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    ABSTRACT: Two experiments were performed to study the interaction between 3,3′,4,4′,5-pentachlorobiphenyl (CB 126) and benzo[a]pyrene (BaP) in dab (Limanda limanda). The first experiment involved four groups: a group pretreated with 10 μg/kg CB 126 which was exposed to 2 mg/kg BaP 6 days later, groups treated with CB 126 and BaP only and a control group. The second experiment was similar, except the BaP dosage level was 50 mg/kg. CB 126 caused a shift in the pattern of BaP metabolites in bile of dab treated with 2 mg/kg BaP, but no such shift could be observed in the dab treated with 50 mg/kg BaP. This correlated with ethoxyresorufin-O-deethylase (EROD) induction which occurred only after exposure to CB 126 or 50 mg/kg BaP. Further, pretreatment with CB 126 caused a decreased amount of BaP DNA adducts formed after treatment with 50 mg/kg BaP. Glutathione S-transferase (GST) activities were not affected by any of the treatments. The results suggest that the pattern of metabolites in bile depends on cytochrome P450 induction status, whereas the amount of DNA adducts formed does not.
    No preview · Article · Jul 2000 · Marine Environmental Research
  • R. F. Nolting · A. Ramkema · J. M. Everaarts
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    ABSTRACT: Trace and major elements were measured in sediment cores collected at the shelf and continental slope of the Banc d’Arguin (Mauritania). Most of the sediments have a calcium carbonate content >50% and as a consequence have a low aluminium (<1.5%) and iron (<1.0%) content. The concentrations of the latter two elements increase down slope. Based on the major elemental composition, the sediments seem to be well mixed and concentration gradients are only observed on a spatial distribution. Concentrations of Cu, Cd, Zn, Ni and Pb are low and approximately equal to “natural background” values, indicating negligible anthropogenic influences. An exception is Cd for which very high values were found in the northern most part of the research area, close to Nouadhibou. A possible explanation for this high Cd content can be the existence of phosphate rich sediments with a high affinity for Cd. Small increases in the available trace metal concentrations (exchangeable fraction, 0.1 N HCl treated) observed near the sediment surface could be attributed to early diagenetic processes, and not to pollution effects. The inputs from the Saharan dust plume with low trace metal contents, the transport of small particles with higher trace metal content down slope together with the escape of redissolved trace metals from the sediment, and the absence of a supply of metal rich material to the Banc d’Arguin, has created a metal poor environment. There is clear evidence of trace metal redistributions, associated with Mn recycling. Mean enrichment factors, calculated relative to the crustal abundance, show that Zn, Pb and Cd are equal to unity and Cu and Ni below unity. These observations suggest that the Cu and Ni contents in sediments of Banc d’Arguin are depleted relative to the accepted values in the earth crust. The very low trace metal concentrations detected in these sediments can be taken as “baseline” values for unpolluted sediments in the global ocean coastal zone.
    No preview · Article · Apr 1999 · Continental Shelf Research
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    ABSTRACT: In PLHC-1 hepatoma cells, benzo[a]pyrene (B[a]) caused a maximum induction of cytochrome P4501A (CYP1A) activity, measured as ethoxyresorufin O-deethylation (EROD), after 4 to 8 h of exposure, depending on the B[a]P concentration. The decline of EROD activity at longer exposure times was probably caused by the rapid metabolism of B[a]P in this system. In subsequent experiments, PLHC-1 cells were preinduced with PCB 126 for 24 h and then received a dose of 10, 100, or 1,000 nM {sup 3}H-B[a]P. A 1-nM concentration of PCB 126 caused an 80-fold induction of CYP1A activity, resulting in an increase in B[a]P metabolism of less than 10%, except at the highest concentration of B[a]P where a 50% increase was observed. In another experiment, an 80-fold induction of CYP1A activity caused a 20% increase in the metabolism of B[a]P and RNA adduct formation was increased approximately twofold. These results indicate that, at exposure concentrations up to 100 nM B[a]P, CYP1A activity is not rate limiting for B[a]P metabolism. Furthermore, CYP1A seems to also be specifically involved in B[a]P activation in PLHC-1 cells. However, CYP1A induction causes only a relatively small increase in activation, probably because of the action of other enzymes involved in B[a]P activation and deactivation.
    No preview · Article · Mar 1999 · Environmental Toxicology and Chemistry
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    ABSTRACT: The effect of -glutamylmethylamide(GMA), one of the components of green tea extract, on the blood pressure in spontaneously hypertensive rats (SHR) was investigated. The effect of glutamic acid and r-glutamylethylamide (theanine), which is structually similar to GMA, was also examined. When SHR were injected with glutamic acid (2000mg/kg), the blood pressure was not altered. The same dose of theanine decreased it significantly. GMA administration to SHR reduced the blood pressure significantly, and its degree of hypotensive action was more effective than that by theanine administration.
    No preview · Article · May 1998 · Marine Pollution Bulletin
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    ABSTRACT: Seastars (Asterias rubens L.) were collecte d at sampling locations in different areas along transects radiating into the southern North Sea, representing areas impacted by contaminants to different degrees. Strand breakage in DNA isolated from tissue of the pyloric caeca was measured by the alkaline unwinding assay, modified to allow for the isolation of highly intact DNA. The interpretation of the results is based on the incidence of DNA strand breaks (expressed as the double:total DNA ratio or F value, indicating the degree of double-strandedness). The cytochrome P-450 concentration and the benzo [a] pyrene (BaP) hydroxylase activity were measured in microsomal fractions of the pyloric caeca. The chlorinated biphenyl (CB) congeners in tissue samples from the digestive gland were determined by temperature-programmed gas-chromatography, with a CPSil8 capillary column as the stationary phase, hydrogen as the carrier gas and 63Ni-electron capture detection. Areas where seastars showed different DNA integrity could be described. The highest integrity (0.75 < f="">< 0.85)="" was="" found="" in="" the="" off-shore="" reference="" sites="" of="" the="" dogger="" bank="" and="" southern="" bight.="" the="" mean="" f="" value="" in="" seastars="" from="" most="" sampling="" locations="" varied="" between="" 55="" and="" 75%.="" the="" lowest="" dna="" integrity="" (0.35="">< f="">< 0.55)="" was="" found="" in="" specimens="" obtained="" from="" sampling="" locations="" near="" the="" river="" rhine="" delta,="" along="" the="" dutch="" coast="" and="" at="" two="" expected="" uncontaminated="" offshore="" areas.="" the="" bap="" hydroxylase="" activity="" was="" relatively="" high="" near="" the="" mouth="" of="" the="" rivers="" rhine="" and="" scheldt,="" but="" also="" at="" a="" supposedly="" clean="" site="" near="" dogger="" bank.="" the="" concentration="" of="" cb="" congeners="" in="" the="" pyloric="" caeca="" of="" seastars="" decreased="" along="" transects="" radiating="" into="" the="" southern="" north="" sea="" from="" the="" coastal="" areas="" of="" the="" netherlands;="" the="" highest="" concentrations="" were="" in="" the="" nearby="" coastal="" areas="" and="" the="" lowest="" were="" in="" the="" open="" sea="" sampling="" locations.="" the="" data="" indicate="" that="" there="" might="" be="" a="" relationship="" between="" pollution="" from="" the="" rivers="" rhine,="" meuse="" and="" scheldt="" and="" the="" incidence="" of="" dna="" strand="" breaks="" and/or="" bap="" hydroxylase="">
    No preview · Article · Jan 1998 · Ecotoxicology
  • J. M. Everaarts
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    ABSTRACT: To assess the health status of the North Sea, DNA damage in seastar (Asterias rubens L.) was studied by establishing the level of integrity of DNA (strand breaks) isolated from pyloric caeca of these organisms, collected at 16 places in the southern half of the North Sea. On the basis of the fraction of intact double-stranded DNA (F-value) the sampling locations were classified into three clusters: cluster 1, an area (Dutch coastal zone and a deeper zone near the English coast) with a low DNA integrity (F < 0.50, which means that more than 50% of the DNA exhibited strand breaks); cluster 11, areas (coastal sites in the Southern and German Bights and the offshore region of the Dogger Bank) with intermediate integrity of DNA (0.50 < F < 0.75), and cluster 111, an area (central part of the southern North Sea, south of the Dogger Bank) with high DNA integrity (F > 0.75, indicating that less than 25% of the DNA exhibited strand breaks).
    No preview · Article · May 1997 · Journal of Sea Research
  • J Smeets · A Voormolen · J Everaarts · W Seinen · M Van den Berg

    No preview · Article · Jan 1997
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    JM Everaarts · A. Sarkar
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    ABSTRACT: The DNA damage in seastars (Asterias rubens) was studied by measuring the level of integrity of DNA isolated from pyloric caeca of the organisms in order to assess the state of pollution of the North Sea. The effect of various genotoxic chemicals on the integrity of DNA was determined by the level of double strandedness with respect to total DNA following time-dependent partial alkaline unwinding assay. On the basis of the level of integrity of DNA from seastars the study area was distinguished into three clusters: Cluster-I, the highly polluted area (coastal and estuarine zones) with low integrity of DNA (27-43% integrity), Cluster-II, the moderately polluted area (offshore region) with medium integrity of DNA (49-64% integrity) and Cluster-III, less polluted area (near Dogger bank region) with high integrity of DNA (70-87% integrity).
    Full-text · Article · Dec 1996 · Water Science & Technology
  • J M Everaarts · K SaralaDevi
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    ABSTRACT: In the central and southern North Sea, and in the Dutch coastal zone, total cadmium (Cd) concentrations in water are 0.02 {+-} 0.01 μg/L and 0.06 {+-} 0.02 μg/L, respectively Cadmium in the estuarine waters of the Dutch Wadden Sea varied from 0.3 {+-} 0.01 μg/L in the western part to 0.08 {+-} 0.03 μg/L in the eastern part. In whole sediment, the Cd background concentration for the Wadden Sea is 0.5 {+-} 0.01 μg/g dry weight (dw), whereas the reference concentration is 0.08 {+-} 0.02 μg/g dw. The concentrations of total-Cd in surface bulk sediments (0-2 cm) of the central North Sea (Oyster Grounds), and of intertidal mud-flats in the western Wadden Sea varied from 0.05 to 0.15 μg/g dw and from 0.13 to 0.46 μg dw, respectively (calculated from Kahn et al. 1992). These concentration ranges match the reference Cd concentration for Wadden Sea whole sediment (0.5 {+-} 0.01) μg/g dw. Cadmium concentrations in surface sediments of the Dutch coastal zone and estuaries are only slightly elevated compared to the 0.2 μg/g dw, considered as the background concentrations in pristine areas, but well below the level of 10 μg/g dw at heavily contaminated sites. This laboratory study reports on the distribution of cadmium in the sediment column, and the uptake in the blood/coelomic fluid, intestine and body-wall of lugworms at low cadmium concentration exposure. The aim was to determine possible interaction between the vertical distribution of sediment-bound cadmium and the bioturbating activity of lugworms. 14 refs., 3 figs., 2 tabs.
    No preview · Article · Dec 1996 · Bulletin of Environmental Contamination and Toxicology
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    ABSTRACT: Common whelks (Buccinum undatum) from the open North Sea show imposex; the development of male sexual characteristics in female prosobranch gastropods. A correlation with shipping intensities has been established (Ten Hallers-Tjabbes et al., 1994) and tributyltin (TBT), the active biocide in anti-fouling paints, was expected to be the cause. To study the supposed cause—effect relationship, adult whelks were experimentally exposed to TBT. Juvenile B. undatum, produced by the experimental specimens, were also exposed in ovo or just after hatching during this experiment and developed male sexual characteristics (a penis and/or a vas deferens) in a dose-dependent manner already after 10 months more than 80% of the young B. Undatum exposed to nominal TBT concentrations 100 ng TBT/litre developed these male sexual organs. Adult females, however, showed no signs of imposex, although they were exposed for 9 months to the same TBT concentrations as their offspring. In adult females exposed to a dose of 1 μg TBT/litre, a TBT body burden of > 300 ng Sn/g dry weight was measured.
    No preview · Article · Jun 1996 · Marine Environmental Research
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    Theunis Piersma · Jan M. Everaarts · Joop Jukema
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    ABSTRACT: We examined hemoglobin concentration, hematocrit and mean cell hemoglo-bin concentration (MCHbC) in Bar-tailed Godwits Limosa lapponica during the latter half of their staging period in May in the Wadden Sea of The Netherlands. Here they recover from a 4,000-5,000 km long flight from West African wintering areas and refuel in prep-aration for a flight of similar length toward the arctic Siberian breeding grounds. Hemoglobin concentration and hematocrit levels showed no differences between the sexes, but were higher than expected for a bird species of their size. Bar-tailed Godwits that were on schedule with regard to molt and body mass gains, had elevated concentrations of red blood cells all the time during 19-30 May. In contrast, late-arriving, nutritionally stressed individuals, recognizable by the absence of contour feather molt, showed an increase in both hemoglobin concentration and hematocrit over time before scheduled departure on 1 June, converging to similar values as the group of high migratory quality. There were no time-related and categorical variations in MCHbC. We interpret the relatively low concentrations of red blood cells in late arriving light-weight individuals to indicate that long-distance migration flights may result in light anemia. The quick recovery and maintenance of high hemoglobin and hematocrit levels throughout the latter half of the staging period indicates that high concentrations of red blood cells are as necessary for rapid refuelling as for long-distance flights. The increased viscosity of blood with high hematocrit values was reflected in co-occurring increases in the size of the heart.
    Full-text · Article · May 1996 · The Condor
  • CC tenHallersTjabbes · JM Everaarts · BP Mensink · JP Boon
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    ABSTRACT: Recent surveys in the southern and central North Sea and the Dutch Wadden Sea revealed that the whelk Buccinum undatum L. can no longer be found in areas where whelks were abundant twenty or more years ago. The decline of whelk populations tends to coincide with areas of various, intense human activities, which may cause either pollution or physical damage. Potential causes for the decline of whelks from the southern North Sea and coastal areas are discussed and considered in view of North Sea ecology and protective policies for the North Sea.
    No preview · Conference Paper · Mar 1996

  • No preview · Article · Dec 1995 · Marine Environmental Research