D Shea

North Carolina State University, Raleigh, North Carolina, United States

Are you D Shea?

Claim your profile

Publications (10)25.98 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Exposure to toxicants is one factor hypothesized to influence population growth of the northern right whale. Organo-chlorines in right whale skin, feces, and prey were measured and used to identify factors influencing exposure and bioaccumulation. Concentrations of 30 polychlorinated biphenyls (PCBs) (5.7 ± 8.9 μg/g lipid) and 20 pesticides (11.4 ± 15.4 μg/g lipid) in skin biopsies were consistent with other baleenopterids. Concentrations in feces and prey were two orders of magnitude less than in biopsies. In principal component analysis, organochlorines in biopsies matched those from Bay of Fundy, Canada, zooplankton, whereas feces were like Cape Cod, USA, copepods. Year of biopsy collection was the principal factor associated with differential accumulation of nonmetabolizable PCBs, 4,4′-DDE, and dieldrin. Biopsies collected during winter had lower concentrations of lipid and metabolizable compounds than biopsies collected during summer. Concentrations of metabolizable PCBs increased with age in males. The bioaccumulation patterns implied that blubber burdens change annually because of the ingestion of different prey or prey from distinct locations and the release of some organochlorines stored in blubber during lipid depletion in winter. Because biopsy concentrations were lower than those found in marine mammals affected by PCBs and DDTs, we do not have evidence that the endangered whales bioaccumulate hazardous concentrations of organochlorines.
    Environmental Toxicology and Chemistry 11/2009; 19(3):654 - 666. · 2.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Organochlorine concentrations were measured in white-sided dolphins, pilot whales, and their prey from the Gulf of Maine and used to identify species, tissue, and gender differences, and trophic transfer trends, in bioaccumulation. Polychlorinated biphenyl concentrations ([PCB]) in dolphin blubber (13 +/- 7.1 micrograms/g fresh wt.) were twice those in pilot whales, but pesticide concentrations (20 +/- 13 micrograms/g fresh) were similar between species. 4,4'-DDE, trans-non-achlor, Cl6(153) and Cl6(138) concentrations were highest. Skin tissues had more recalcitrant organochlorines than the internal organs. Male dolphins bioaccumulated higher concentrations of nonmetabolizable PCBs and hexachlorocyclohexane (HCH) isomers, whereas pilot whales had no gender-related differences in bioaccumulation. Pilot whales, mackerel, and herring had proportionately higher concentrations of DDTs, whereas [PCB] were higher in dolphins and squid. Although these odontocetes feed at the same trophic level and store a similar suite of contaminants, dolphins bioaccumulated higher and potentially hazardous 4,4'-DDE and PCB concentrations from food in their more geographically restricted range.
    Marine Environmental Research 03/2001; 51(1):29-50. · 2.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We measured rates of oxidative metabolism of two tetrachlorobiphenyl (TCB) congeners by hepatic microsomes of two marine mammal species, beluga whale and pilot whale, as related to content of selected cytochrome P450 (CYP) forms. Beluga liver microsomes oxidized 3,3',4,4'-TCB at rates averaging 21 and 5 pmol/min per mg for males and females, respectively, while pilot whale samples oxidized this congener at 0.3 pmol/min per mg or less. However, rates of 3,3',4,4'-TCB metabolism correlated with immunodetected CYP1A1 protein content in liver microsomes of both species. The CYP1A inhibitor alpha-naphthoflavone inhibited 3,3',4,4'-TCB metabolism by 40% in beluga, supporting a role for a cetacean CYP1A as a catalyst of this activity. Major metabolites of 3,3',4,4'-TCB generated by beluga liver microsomes were 4-OH-3,3',4',5-TCB and 5-OH-3,3',4,4'-TCB (98% of total), similar to metabolites formed by other species CYP1A1, and suggesting a 4,5-epoxide-TCB intermediate. Liver microsomes of both species metabolized 2,2',5,5'-TCB at rates of 0.2-1.5 pmol/min per mg. Both species also expressed microsomal proteins cross-reactive with antibodies raised against some mammalian CYP2Bs (rabbit; dog), but not others (rat; scup). Whether CYP2B homologues occur and function in cetaceans is uncertain. This study demonstrates that PCBs are metabolized to aqueous-soluble products by cetacean liver enzymes, and that in beluga, rates of metabolism of 3,3',4,4'-TCB are substantially greater than those of 2,2',5,5'-TCB. These directly measured rates generally support the view that PCB metabolism plays a role in shaping the distribution patterns of PCB residues found in cetacean tissue.
    Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 08/2000; 126(3):267-84. · 2.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Exposure to toxicants is one factor hypothesized to influence population growth of the northern right whale. Organochlorines in right whale skin, feces, and prey were measured and used to identify factors influencing exposure and bioaccumulation. Concentrations of 30 polychlorinated biphenyls (PCBs) and 20 pesticides in skin biopsies were consistent with other baleenopterids. Concentrations in feces and prey were two orders of magnitude less than in biopsies. In principal component analysis, organochlorines in biopsies matched those from Bay of Fundy, Canada, zooplankton, whereas feces were like Cape Cod, USA, copepods. Year of biopsy collection was the principal factor associated with differential accumulation of nonmetabolizable PCBs, 4,4{prime}-DDE, and dieldrin. Biopsies collected during winter had lower concentrations of lipid and metabolizable compounds than biopsies collected during summer. Concentrations of metabolizable PCBs increased with age in males. The bioaccumulation patterns implied that blubber burdens change annually because of the ingestion of different prey or prey from distinct locations and the release of some organochlorines stored in blubber during lipid depletion in winter. Because biopsy concentrations were lower than those found in marine mammals affected by PCBs and DDTs, the authors do not have evidence that the endangered whales bioaccumulate hazardous concentrations of organochlorines.
    Environmental Toxicology and Chemistry 03/2000; 19(3). · 2.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Contaminant exposure is widespread among marine mammals but is of unknown significance. This study characterized organochlorine bioaccumulation in pilot whales, and these bioaccumulation patterns are proposed as representative of Northwest (NW) Atlantic cetacea. Samples were collected from whales stranded in Massachusetts and caught in nets. Polychlorinated biphenyl (PCB) and chlorinated pesticide concentrations were determined via GC/ECD and found to be similar to those reported for other NW Atlantic odontocetes. The organochlorine in highest concentration was 4,4{prime}-DDE, followed by trans-nonachlor, 4,4{prime}-DDD, dieldrin, cis-chlordane, C14(52), C15(95), C15(101), C15(118), C16(138), C16(149), C16(153), C17(180), and C17(187). The concentration of 19 pesticides was higher in blubber than liver. The concentration of 26 PCB congeners was also greater in blubber than liver. Principal component analysis and ANOVA indicated that blubber accumulated proportionately more of the most recalcitrant compounds, such as 4,4{prime}-DDE and nonmetabolizable PCBs, compared to liver. Whales that stranded together had more similar bioaccumulation than animals of the same gender or maturity. The high variation among individuals in tissue concentrations and the similarity within a stranding group suggest that pilot whale pods are exposed to a large range of pollutant sources, such as through different prey and feeding locations.
    Environmental Toxicology and Chemistry 03/2000; 19(3). · 2.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Contaminant exposure is widespread among marine mammals but is of unknown significance. This study characterized organochlorine bioaccumulation in pilot whales, and these bioaccumulation patterns are proposed as representative of Northwest (NW) Atlantic cetacea. Samples were collected from whales stranded in Massachusetts and caught in nets. Polychlorinated biphenyl (PCB) and chlorinated pesticide concentrations were determined via GC/ECD and found to be similar to those reported for other NW Atlantic odontocetes. The organochlorine in highest concentration was 4,4′-DDE, followed by trans-nonachlor, 4,4′-DDD, dieldrin, cis-chlordane, Cl4(52), Cl5(95), Cl5(101), Cl5(118), Cl6(138), Cl6(149), Cl6(153), Cl7(180), and Cl7(187). The concentration of 19 pesticides was higher in blubber (21 ± 26 μg/g lipid “ppm”) than liver (5.0 ± 7.1 ppm). The concentration of 26 PCB congeners was also greater in blubber (7.6 ±7.1 ppm) than liver (0.4 ± 7.3 ppm). Principal component analysis and ANOVA indicated that blubber accumulated proportionately more of the most recalcitrant compounds, such as 4,4′-DDE and nonmetabolizable PCBs, compared to liver. Whales that stranded together had more similar bioaccumulation than animals of the same gender or maturity. The high variation among individuals in tissue concentrations and the similarity within a stranding group suggest that pilot whale pods are exposed to a large range of pollutant sources, such as through different prey and feeding locations.
    Environmental Toxicology and Chemistry 02/2000; 19(3):667 - 677. · 2.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The poor recovery of multiple whale populations raises concern for the integrity of the US marine environment. Fifty organochlorines were measured in samples of pilot whales, white-sided dolphins, endangered right whales and their prey. As expected from their high trophic position and proximity to land-based sources, the bioaccumulation of 4,4′-DDE, several chlordanes and polychlorinated biphenyl (PCB) congeners was substantial (ppm) in squid and the stranded odontocetes. Concentrations in fish and right whale biopsies were one to two orders of magnitude less than in odontocetes. Although the prevalent pesticides were different between odontocetes and balaenopterids, the magnitude of pesticide concentrations was similar across species. PCB concentrations were higher in the Gulf of Maine dolphins than pilot and right whales. Gender and tissue type were the important characteristics contributing to the bioaccumulation patterns observed in dolphins. Season of sample collection and exposure to different prey seemed critical for the bioaccumulation observed in right and pilot whales. Dolphin and pilot whale organs contained ample concentrations of specific compounds, notably 4,4′-DDE, that have been shown to alter endocrine function.
    Marine Environmental Research - MAR ENVIRON RES. 01/2000; 50(1):440-441.
  • [Show abstract] [Hide abstract]
    ABSTRACT: 3,3',4,4'-Tetrachlorobiphenyl (TCB) can induce and inhibit cytochrome P450 1A1 (CYP1A1) in vertebrates. TCB may also suppress CYP1A1 protein levels, but the mechanism is unknown. This study examined transcriptional and translational aspects of hepatic CYP1A1 regulation in the fish scup (Stenotomus chrysops) given single intraperitoneal injections of low (0.1 mg/kg) or high (5 mg/kg) doses of TCB, and sampled over 16 days. The low dose strongly induced hepatic CYP1A1 mRNA (25-fold), protein (12-fold), and activity [ethoxyresorufin O-deethylase (EROD)] (15-fold). The high dose also strongly induced CYP1A1 mRNA (29-fold), in a pattern like that at the low dose, but microsomal CYP1A1 protein content was induced only 4-fold and EROD rates were near control levels. Both TCB doses caused similar increases in microsomal cytochrome b5 content, and in rates of NADPH-cytochrome c (P450) reductase and UDP-glucuronosyltransferase (with p-nitrophenol). The contents of CYP forms other than CYP1A1 (putative CYP2B or CYP3A) were only weakly affected by TCB at either dose. The strong and largely specific post-transcriptional suppression of CYP1A1 content was associated with high concentrations of TCB measured in the liver. Incubation of scup hepatic microsomes with TCB plus NADPH led to a time-dependent inactivation of CYP1A1 that was distinct from catalytic inhibition, and appeared not to involve reactive metabolites of TCB. This in vitro result suggests that TCB may inactivate CYP1A1 in vivo, which could account for the apparent antagonistic effect of TCB on CYP1A1 induction.
    Biochemical Pharmacology 05/1997; 53(7):1029-40. · 4.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The metabolism of the polychlorinated biphenyl congener 3,3',4,4'-tetrachlorobiphenyl (TCB) was examined in vitro and in vivo in the marine fish scup (Stenotomus chrysops). Untreated scup liver microsomes catalyzed metabolism of TCB with an estimated KM of 0.7 microM, at a rate < or = 0.13 pmol/min/mg. Metabolism was NADPH-dependent and inhibited by cytochrome c and CO, indicating cytochrome P450 (CYP) involvement. alpha-Naphthoflavone strongly inhibited microsomal TCB metabolism, and treatment of fish with CYP1A inducers increased the rates by approximately 2-fold, suggesting involvement of CYP1A. Scup were injected intraperitoneally with 0.1 or 5 mg TCB/kg and sampled on days 1-16 after treatment (after 3 days without food at each sampling). Concentrations of unmetabolized TCB in liver peaked on day 5 in low dose fish and on day 12 in high dose fish. In both groups the TCB content in the liver had declined 60% or more by day 16, suggesting depuration or redistribution from the liver. GC and MS revealed TCB and TCB metabolites in bile within 24 hr of treatment. The concentrations of TCB and metabolites in bile peaked at the same time that TCB concentrations peaked in the liver. The major metabolites were 5-hydroxy-3,3'4,4'-TCB (5-OH-TCB) and 4-hydroxy-3,3',5,4'-TCB (4-OH-TCB); 2-hydroxy-3,3',4,4'-TCB and 6-hydroxy-3,3',4,4'-TCB were minor metabolites. Animals given the high dose had much less 5-OH-TCB and much more parent TCB in bile than did fish given the low dose. Amounts of 4-OH-TCB in bile did not differ between doses. The reduced excretion of 5-OH-TCB coincided with a suppression of CYP1A in fish given the high dose, that did not occur in low dose fish, consistent with an involvement of CYP1A in TCB metabolism and particularly in formation of 5-OH-TCB. This study provides the first direct demonstration of 3,3',4,4'-TCB metabolism by fish. Data also indicate that these fish are able to eliminate TCB both as parent compound and as metabolites, despite a very slow rate of metabolism in vitro.
    Drug Metabolism and Disposition 05/1997; 25(5):564-72. · 3.36 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Liver lesions including neoplasia and hydropic vacuolation have been described in winter flounder (Pleuronectes americanus) from sites in Boston Harbor, and were highly prevalent near the Deer Island sewage outfall. A marked decline in prevalence of neoplasia has been seen over the period 1987 to 1993 in fish from near the Deer Island outfall. This decline in disease in Deer Island fish correlated with and probably resulted from reported reduced chemical input over that time. Stable isotope ratios suggest that Deer Island winter flounder, in contrast to fish from elsewhere, fed significantly on sewage sludge-derived organic matter prior to 1992 and that their along-shore movement is slight. Between 1991 and 1993 hydropic vacuolation remained much more prevalent in flounder taken near Deer Island and another sewage outfall, than at sites distant (≤45 miles) from the outfalls. Hydropic vacuolation prevalence correlated closely with content of chlorinated hydrocarbon residues in the liver, and in particular with DDT/DDD/DDE. This suggests that between 1991 and 1993 there was a persistent chemical-associated difference in fish from the planned and current outfall sites, and that monitoring of winter flounder will provide necessary assessment of altered chemical carcinogenesis risk during and after the switch to the offshore outfall planned for 1998.
    Marine Pollution Bulletin 01/1996; · 2.53 Impact Factor

Publication Stats

159 Citations
25.98 Total Impact Points

Institutions

  • 1996–2009
    • North Carolina State University
      Raleigh, North Carolina, United States
  • 2001
    • Procter & Gamble
      Cincinnati, Ohio, United States
  • 1996–2000
    • Woods Hole Oceanographic Institution
      • Department of Biology
      Falmouth, MA, United States