Platichthys Stellatus Research Articles

Acute toxicity of a didecyldimethylammonium chloride‐based wood preservative, bardac 2280, to aquatic species

AbstractThe acute toxicity of the antisapstain wood preservative Bardac 2280 (principal active ingredient 80% didecyldimethylammonium chloride, DDAC) was tested with four fish and four aquatic invertebrate species. White sturgeon fry (Acipenser transmontanus) were the most sensitive fish species tested with a 24‐h 50% lethal concentration (LC50) value between 1 and 10 ppb Bardac 2280. The 96‐h LC50 values for the three other fish species ranged from 0.39 ppm for fathead minnows (Pimephales promelas) to 2.0 ppm for juvenile starry flounder (Platichthys stellatus). Developmental stage altered the sensitivity of coho salmon to Bardac 2280, with alevins being approximately twice as sensitive as smolts. Altering salinity up to 30‰ seawater had no significant effect on the toxicity of Bardac 2280 to coho smolts. The 48‐h LC50 values for Daphnia magna, Mysidopsis bahia, Hyalella azteca, and Neomysis mercedis were 0.037 ppm, 0.039 ppm, 0.106 ppm, and 0.947 ppm, respectively. Bardac 2280 characteristically produced steep concentration–response curves for fish, i.e., a concentration range considerably less than 10‐fold for a complete range of mortality, and caused no major symptoms of sublethal stress in juvenile starry flounder following a 24‐h exposure.

Quantitation of CYP1A expression in two flatfish species showing different prevalences of contaminant-induced hepatic disease

English sole ( Pleuronectes vetulus) and starry flounder ( Platichthys stellatus) are two sympatric flatfish species which show markedly different responses to chemical contaminant exposure. Whereas English sole develop hepatic neoplasms, the prevalences of which are strongly linked to exposure to polycyclic aromatic hydrocarbons (PAHs), evidence of neoplasia is virtually nonexistent in starry flounder, even those residing in areas with very high levels of PAH in the sediments. Because PAHs are activated to genotoxic forms by the action of cytochrome P450 1A (CYP1A) in teleosts, we are examining the hypothesis that variation in the hepatic expression of this major inducible cytochrome P450 isozyme may contribute to the differential contaminant response. These two species were captured in the Duwamish Waterway, a contaminated area of Puget Sound, Washington. Catalytic activity of CYP1A [determined as aryl hydrocarbon hydroxylase (AHH) activity] was measured in the liver to quantitatively assess the relative induction of CYP1A in these two species, and AHH activity was significantly higher in English sole than in starry flounder ( p = 0.015). Cellular expression of CYP1A was determined by immunohistochemical localization of tissues, using an avidin-biotin peroxidase complex method, with polyclonal rabbit anti-cod CYP1A. The results showed a markedly reduced expression of CYP1A in hepatocytes of starry flounder, which is consistent with the apparent resistance of this species to the development of hepatocellular neoplasia. This reduced expression of CYP1A in hepatocytes of contaminant-exposed fish was previously seen in oyster toadfish from the Elizabeth River, Virginia, and this species is also apparently resistant to hepatocellular neoplasia.

Isolation and cloning of homologous glutathione S-transferase cDNAs from English sole and starry flounder liver

We are currently investigating hepatic glutathione S-transferase (GST) expression in English sole ( Pleuronectes vetulus) and starry flounder ( Platichthys stellatus), two closely related benthic fish that exhibit striking differences in the prevalences of contaminant-associated liver neoplasia. Alignment of cDNA sequences encoding plaice ( Pleuronectes platessa) liver GST (PLGST-A, a theta class GST, Leaver et al., 1993) and a GST-related lens crystallins protein from octopus ( Octopus vulgaris) revealed conserved regions for oligonucleotide primer design for polymerase chain reaction (PCR)-based studies of sole and flounder GSTs. Reverse-transcriptase-PCR (RT-PCR) analysis of sole and flounder hepatic total mRNA yielded 469 nucleotide cDNA fragments that displayed extensive sequence homology (98%) to plaice GST-A. Northern blotting analysis of English sole and starry flounder liver using the PCR product from English sole as a probe detected a single band of approximately 1000 nucleotides that was highly expressed in English sole and in starry flounder liver. Biochemical and immunological studies using diagnostic GST reference substrates and class specific polyclonal antibodies suggested little homology among English sole and starry flounder GSTs, and rodent alpha, mu, and pi class GSTs. Interestingly, English sole, the species exhibiting a relatively high prevalence of contaminant-associated liver neoplasia, exhibited higher hepatic GST activity toward the environmental epoxides aflatoxin B 1-8,9-epoxide (AFBO) and benzo[ a]pyrene- trans-7,8-dihydrodiol-9,10-epoxide- anti (BPDE). BPDE, in particular, is a carcinogenic epoxide intermediate implicated as a possible causative agent in the etiology of these hepatic lesions. In summary, our studies indicate that a GST related to non-mammalian theta class GST is conserved in marine flatfish. Further mechanistic studies are necessary to determine the role of GSTs in the observed susceptibility differences among English sole and starry flounder to sediment-associated carcinogens.

Toxicopathic hepatic lesions as biomarkers of chemical contaminant exposure and effects in marine bottomfish species from the Northeast and Pacific Coasts, USA

Relationships between toxicopathic hepatic lesions and chemical contaminants in sediments, stomach contents, liver and bile were evaluated in English sole, starry flounder and white croaker from 27 sites on the Pacific Coast, and winter flounder from 22 sites on the Northeast Coast of the USA, as part of the NOAA's National Benthic Surveillance Program (NBSP). Prevalences of and relative risks for most toxicopathic lesions were significantly higher in fish from contaminated sites in Puget Sound, the Los Angeles area, and San Francisco and San Diego Bays on the Pacific Coast, and in Boston Harbor, Raritan Bay and certain urban sites in Long Island Sound on the Northeast Coast. Exposure to polycyclic aromatic hydrocarbons (PAHs), PCBs, DDTs, chlordanes and dieldrin were significant risk factors for all lesion types in Pacific Coast species. In winter flounder from the Northeast Coast, exposure to PAHs, DDTs or chlordanes were significant risk factors only for hydropic vacuolation, nonneoplastic proliferative and nonspecific necrotic lesions, and less commonly for neoplasms and foci of cellular alteration. Risk of hepatic disease generally increased with fish age, but sex was rarely a risk factor. Temporal trends analyses of hepatic lesion prevalences in starry flounder, white croaker and English sole from NBSP sites on the Pacific Coast failed to detect any significant monotonic increases or decreases in lesion prevalence. Recent studies utilized a two-segment ‘hockey-stick’ regression technique applied to NBSP data to determine threshold levels of sediment PAHs, which are clearly associated with toxicopathic hepatic lesions in English sole. Significant chemical threshold levels for these lesions are in the vicinity of 500–1000 ppb ΣPAHs in sediment, values considerably lower than those reported for other techniques. Application of this dose-response model to these subacute and chronic lesions involved in hepatocarcinogenesis, provides nonlethal sediment quality assessment endpoints for contaminant concentrations that may have long term health implications for chronically exposed native fish populations. Overall, these relationships provide strong evidence for environmental contaminants as etiologic agents for hepatic lesions in several marine bottomfish species, and clearly indicate their utility as biomarkers of contaminant-induced effects in wild fish, whether in national and regional biomonitoring programs or within the injury assessment phase of the legal process of assessing damage to fishery resources.

ACUTE TOXICITY OF A DIDECYLDIMETHYLAMMONIUM CHLORIDE-BASED WOOD PRESERVATIVE, BARDAC 2280, TO AQUATIC SPECIES

The acute toxicity of the antisapstain wood preservative Bardac 2280 (principal active ingredient 80% didecyldimethylammonium chloride, DDAC) was tested with four fish and four aquatic invertebrate species. White sturgeon fry (Acipenser transmontanus) were the most sensitive fish species tested with a 24-h 50% lethal concentration (LC50) value between 1 and 10 ppb Bardac 2280. The 96-h LC50 values for the three other fish species ranged from 0.39 ppm for fathead minnows (Pimephales promelas) to 2.0 ppm for juvenile starry flounder (Platichthys stellatus). Developmental stage altered the sensitivity of coho salmon to Bardac 2280, with alevins being approximately twice as sensitive as smolts. Altering salinity up to 30‰ seawater had no significant effect on the toxicity of Bardac 2280 to coho smolts. The 48-h LC50 values for Daphnia magna, Mysidopsis bahia, Hyalella azteca, and Neomysis mercedis were 0.037 ppm, 0.039 ppm, 0.106 ppm, and 0.947 ppm, respectively. Bardac 2280 characteristically produced steep concentration–response curves for fish, i.e., a concentration range considerably less than 10-fold for a complete range of mortality, and caused no major symptoms of sublethal stress in juvenile starry flounder following a 24-h exposure.

Hydropic vacuolation in the liver of three species of fish from the U.S. West Coast: lesion description and risk assessment associated with contaminant exposure.

Hydropic vacuolation (HydVac) of biliary epithelial cells and hepatocytes is described for 3 species of U.S. West Coast bottom fishes. Risk assessment analyses are also conducted to determine if the prevalence of this lesion increases in association with contaminant exposure and site of capture. The morphology of HydVac in starry flounder Platichthys stellatus, white croaker Genyonemus lineatus and rock sole Lepidopsetta bilineata was similar to that described in winter flounder Pleuronectes americanus from the U.S. Atlantic Coast, especially in that HydVac most commonly affected biliary epithelial cells. Hydropic vacuolation was the most prevalent liver lesion in starry flounder and white croaker captured from contaminated environments. Risk assessment analyses confirmed that the relative risk for HydVac increased with the presence of aromatic and chlorinated hydrocarbons in sediment, fish bile, and fish liver for these species. Hydropic vacuolation also frequently occurred in rock sole, but the lesion showed no clear association with contaminant exposure in this species. The types of liver lesions that were useful biomarkers of contaminant effects in fish depended on the species and this factor must be taken into account when evaluating histopathological biomarkers of response to contaminant exposure.

Purification and Partial Characterization of English Sole (Pleuronectes vetulus) Vitellogenin

Vitellogenin (VTG) was purified by double-step chromatography from plasma of male English sole treated with 17β-estradiol. The intact protein appeared to exist as a dimer in two forms of approximately 300 and 320 kDa and had an isoelectric point of 6.63. In SDS-PAGE, it was reduced to a single monomer of approximately 130 kDa. In immunoblotting, the protein showed cross-reactivity with coho salmon VTG antiserum. Native PAGE (sample not treated with the reducing agent mercaptoethanol) and immunoblotting of plasma from control and estradiol-treated male sole and gravid female sole demonstrated that the putative English sole VTG was normally female specific and estradiol inducible in males. It was immunocytochemically localized in liver and ovary of English sole, rock sole and starry flounder, using polyclonal antiserum to the purified protein from the estradiol-treated male English sole. The protein was characterized as a phospholipoglycoprotein by native PAGE, staining the gels for phosphorus with methyl green, for lipid with Sudan black B and for carbohydrate by an improved periodic-acid Fuchsin sulfite method. The amino acid composition of the putative VTG was generally similar to that of VTGs from other teleosts, with the non-polar amino acids alanine, valine, leucine and isoleucine accounting for one-third of the total amino acids present. However, English sole vitellogenin contained a higher proportion of leucine and a lower proportion of glycine than most other teleost vitellogenins isolated to date.

Chemical contamination and associated liver diseases in two species of fish from San Francisco Bay and Bodega Bay

Starry flounder (Platichthys stellatus), white croaker (Genyonemus lineatus) and sediments were collected annually from selected sites within San Francisco Bay, and a reference site in Bodega Bay between 1984--1991. Fish livers were examined for toxicopathic lesions and analysed for selected chlorinated hydrocarbons (CHs) such as PCBs, DDTs, chlordanes and dieldrin; sediment and fish stomach contents were analysed for polycyclic aromatic hydrocarbons (PAHs) and CHs; and bile was analysed for PAH metabolites. Sediment concentrations of PAHs, PCBs and DDTs; bile concentrations of PAH metabolites; and liver concentrations of PCBs, dieldrin and chlordanes were generally significantly higher at all San Francisco Bay sites compared to the Bodega Bay reference site. For both species, hydropic vacuolation of biliary epithelial cells was the most prevalent liver lesion detected and was statistically associated with sediment and tissue concentrations of PAHs or their metabolites, PCBs, DDTs, chlordanes and dieldrin. Temporal trends analyses showed that at Hunters Point, sediment PAHs and CHs increased between 1984--1991, while liver concentrations of CHs decreased. Liver concentrations of dieldrin in starry flounder decreased at all three San Francisco Bay sites

Biochemical and molecular characterization of glutathione S-transferase expression in English sole and starry flounder

Biochemical and molecular characterization of glutathione S-transferase expression in English sole and starry flounder

Trophic Ecology of the Dominant Fishes in Elkhorn Slough, California, 1974-1980

Food habits of the dominant fishes collected from 1974 to 1980 at eight locations in Elkhorn Slough, California, and the adjacent ocean were investigated. Epifaunal crustacea was the major prey group identified from stomach contents of more than 2,000 fishes, followed by epifaunal and infaunal worms, and molluscs. Overall, 18 fish species consumed 263 different prey taxa, ranging from 10 taxa to 125 taxa per fish species and including 99 crustacean, 56 polychaete, and 39 molluscan taxa. Mean prey richness was greatest at stations near the ocean and lowest at inshore stations. Detailed dietary data for all prey taxa were summarized as trophic spectra for each fish species. Trophic spectra represented functional groups of prey and were used for comparisons of dietary similarity. Cluster analyses, based on trophic spectra, resulted in four feeding guilds of fishes. Of 18 fish species, seven (Amphistichus argenteus, Leptocottus armatus, Embiotoca jacksoni, Clevelandia ios, Gillichthys mirabilis, Cymatogaster aggregata, andCitharichthys stimaeus) fed principally on epifaunal crustacea. Four species (Pleuronectes vetulus, Platichthys stellatus, Phanerodon furcatus, andMyliobatus californica) consumed mostly molluscs and infaunal worms. Two species (Psettichthys melanostictus andTriakis semifasciata) fed on mobile crustacea, and five species (Hyperprosopon anale, Engraulis mordax, Clupea pallasi, Atherinopsis californiensis, andAtherinops affinis) fed largely on zooplankton and plant material. Our results suggest that high food availability enhances the nursery function of imshore habitats, and emphasize the importance of invertebrate prey populations and the indirect linkage of plant production to the ichthyofaunal assemblarly marine immigrant species that are likely ‘estuarine dependent’.

Sediment preference in juvenile pacific flatfishes

Behavioural preference tests were used to determine if sediment selection played a role in habitat choice. Four species of juvenile pleuronectids were given a choice of eight sediments in a carousel and final choices were recorded after 20 h. Juvenile flatfishes demonstrated strong selection for sediments less than 500 μm. Juvenile starry flounder ( Platichthys stellatus) selected larger particles with increasing fish size. Starry flounder under 25 mm in length chose mud, 50–80 mm fish chose mud and mixed mud sediments and larger juveniles (>150 mm) confined themselves to find sand. Juvenile halibut ( Hippoglossus stenolepis) at 50–80 mm preferred a combination of mud and fine sand and were spatially segregated. Yellowfin sole ( Pleuronectes asper) at 50–80 mm showed a slight preference for mud and mixed mud sediments over sand, a selection that became stronger in larger (>150 mm) fish. Juvenile rock sole ( Pleuronectes bilineatus) at 50–80 mm preferred substrata of sand and mixed sand nearly 90% of the time. All species seldom selected sediments which were too coarse to allow the flatfishes to bury themselves, such as granular or pebble substrata. The results of these laboratory studies can be used to predict the distribution of juvenile flatfishes in a nursery area.

Relationships between toxicopathic hepatic lesions and exposure to chemical contaminants in English sole (Pleuronectes vetulus), starry flounder (Platichthys stellatus), and white croaker (Genyonemus lineatus) from selected marine sites on the Pacific Coast, USA.

Relationships between hepatic lesions and chemical contaminant concentrations in sediments, stomach contents, liver tissue, and bile were statistically evaluated in three species of bottomfish, English sole (Pleuronectes vetulus), starry flounder (Platichthys stellatus), and white croaker (Genyonemus lineatus), captured from 27 urban and nonurban sites on the Pacific Coast from Alaska to southern California. Lesions detected were neoplasms, preneoplastic foci of cellular alteration, nonneoplastic proliferative lesions, unique or specific degenerative/necrotic lesions, nonspecific degenerative/necrotic lesions, and hydropic vacuolation of biliary epithelial cells and hepatocytes. In general, lesion prevalences were significantly higher in all three species captured at chemically contaminated urban sites, and certain lesions had significantly higher relative risks of occurrence at urban sites in Puget Sound, San Francisco Bay, the vicinity of Los Angeles, and San Diego Bay. Concentrations of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, DDT and its derivatives, and chlordanes and dieldrin in sediment, stomach contents, liver, and fluorescent aromatic compounds in bile were significant risk factors for the occurrence of neoplastic, preneoplastic, nonneoplastic proliferative, and specific degenerative/necrotic lesions, as well as hydropic vacuolation. Fish age also had a significant influence on occurrence of several hepatic lesions, but gender was rarely a significant risk factor. These relationships provide strong evidence for the involvement of environmental contaminants in the etiology of hepatic lesions in several marine bottomfish species and clearly indicate the utility of these lesions as biomarkers of contaminant-induced effects in wild fish.

Relationships between Toxicopathic Hepatic Lesions and Exposure to Chemical Contaminants in English Sole (Pleuronectes vetulus), Starry Flounder (Platichthys stellatus), and White Croaker (Genyonemus lineatus) from Selected Marine Sites on the Pacific Coast, USA

Relationships between hepatic lesions and chemical contaminant concentrations in sediments, stomach contents, liver tissue, and bile were statistically evaluated in three species of bottomfish, English sole (Pleuronectes vetulus), starry flounder (Platichthys stellatus), and white croaker (Genyonemus lineatus), captured from 27 urban and nonurban sites on the Pacific Coast from Alaska to southern California. Lesions detected were neoplasms, preneoplastic foci of cellular alteration, nonneoplastic proliferative lesions, unique or specific degenerative/necrotic lesions, nonspecific degenerative/necrotic lesions, and hydropic vacuolation of biliary epithelial cells and hepatocytes. In general, lesion prevalences were significantly higher in all three species captured at chemically contaminated urban sites, and certain lesions had significantly higher relative risks of occurrence at urban sites in Puget Sound, San Francisco Bay, the vicinity of Los Angeles, and San Diego Bay. Concentrations of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, DDT and its derivatives, and chlordanes and dieldrin in sediment, stomach contents, liver, and fluorescent aromatic compounds in bile were significant risk factors for the occurrence of neoplastic, preneoplastic, nonneoplastic proliferative, and specific degenerative/necrotic lesions, as well as hydropic vacuolation. Fish age also had a significant influence on occurrence of several hepatic lesions, but gender was rarely a significant risk factor. These relationships provide strong evidence for the involvement of environmental contaminants in the etiology of hepatic lesions in several marine bottomfish species and clearly indicate the utility of these lesions as biomarkers of contaminant-induced effects in wild fish.

Cryotoxicity of antifreeze proteins and glycoproteins to spinach thylakoid membranes — comparison with cryotoxic sugar acids

We have used thylakoids from spinach ( Spinacia oleracea L.) chloroplasts to test the effects of antifreeze proteins (AFP) from the starry flounder ( Platichthys stellatus; AFP-SF) and from the antarctic eel pout ( Austrolycichthys brachycephalus; AFP-AB), and antifreeze glycoproteins (AFGP) from the antarctic fish Dissostichus mawsoni on biological membranes during freezing. Freeze-thaw damage, measured as the release of the lumenal protein plastocyanin from the thylakoid vesicles, was strongly increased in the presence of all proteins tested. Measurements of the time dependence of plastocyanin release in a simplified artificial chloroplast stroma medium showed that all the fish proteins increased damage during the initial rapid phase while only AFGP increased plastocyanin release during the linearly time dependent slow phase. A slow plastocyanin release is also seen in the absence of freezing. It is increased by the presence of AFGP and AFP-AB, but not by AFP-SF. In order to distinguish between the contribution of the polypeptide and the carbohydrate part of AFGP on freeze-thaw damage we investigated the effects of galactose and N-acetylgalactosamine. While galactose was protective, N-acetylgalactosamine increased the rate of plastocyanin release in an artificial stroma medium at −20°C. It had no effect on the rapid phase of damage and was also ineffective at 0°C. The same was found for several other sugar derivatives ( N-acetylglucosamine, gluconic acid, glucoronic acid, galacturonic acid). From these data we conclude that the increased plastocyanin release during the rapid phase of freeze-thaw damage is a function of the polypeptide part of AFGP. The increased rate of plastocyanin loss at longer incubation times both at 0°C and at −20°C may be mediated by the N-acetylgalactosamine moiety of the AFGP, but is strongly amplified by the polypeptide.

Bioindicators of contaminant exposure and sublethal effects in benthic fish from Puget Sound, WA, USA

A suite of chemical and biochemical parameters was measured in three species of benthic flatfish (English sole, Parophrys vetulus; rock sole, Lepidopsetta bilineata; and starry flounder, Platichthys stellatus) sampled from up to five sites in Puget Sound, WA, USA, to assess the sensitivity of the parameters to differences in levels of contaminant exposure and the relative merit of the use of a suite of indices for assessing exposure and sublethal effects. The indices examined were hepatic levels of polychlorinated biphenyls (PCBs) and biliary fluorescent aromatic-compound concentrations, hepatic activities of aryl hydrocarbon hydroxylase and ethoxyresorufin-O-deethylase, and levels of total hepatic GSH and hydrophobic DNA-xenobiotic adducts; the last-mentioned were determined by using the 32P-postlabeling assay. The results showed that the indices examined could discriminate among sites exhibiting different degrees of chemical contamination; however, species differences in the range of response of some indices were observed. Additionally, the use of multiple indices appeared to enhance the assessment of contaminant exposure and sublethal effects.

Possible causes and consequences of variation in age and size at metamorphosis in flatfishes (pleuronectiformes): An analysis at the individual, population, and species levels

Observations on metamorphic ages and sizes in flatfishes are synthesized within a hierarchical framework which ascends from individual to population to species levels. Examples of observations and inferences are given for each level with emphasis on variation among individuals within populations. At the species level, size at metamorphosis ranges from ≈4 to 120 mm and is log-normally distributed. Species-level estimates of ages at metamorphosis from field-collected flatfish are of low resolution if they are derived as the difference between approximate spawning and inferred settling dates. Temperature is the only environmental factor whose effects on metamorphic traits have been evaluated at the population level. Age at metamorphosis increases by more than twofold and metamorphic size is expected to increase slightly as temperature decreases across the viable range. At the individual level, data are available for starry flounder, Platichthys stellatus, and winter flounder, Pseudopleuronectes americanus. Bivariate distributions of metamorphic ages and sizes for these flounders, schematized as metamorphic envelopes, have different locations and orientations, but similar shapes. Metamorphic age has greater within-population variation and is less influenced by parentage than is metamorphic length. Furthermore, maternal contributions to metamorphic traits exceed paternal ones. Effects of metamorphic trait variation on size distributions of young-of-the-year juveniles were evaluated by simulations. In a benign environment lacking mortality bias, the effect of metamorphic age on juvenile size variation was ≈sixfold greater than the effect of metamorphic size. The impact of metamorphic age on juvenile size variation lessened with extension of the spawning interval and with increased duration of juvenile life prior to capture.

Hepatic xenobiotic metabolizing enzymes in two species of benthic fish showing different prevalences of contaminant-associated liver neoplasms

English sole ( Parophrys vetulus) and starry flounder ( Platichthys stellatus) are closely related benthic fish which show substantial differences in prevalences of contaminant-associated hepatic neoplasms and putatively preneoplastic foci of cellular alteration when captured from estuaries containing a variety of organic chemical contaminants, including polycyclic aromatic hydrocarbons (PAH) and chlorinated hydrocarbons. Because PAH are strongly implicated as causative agents in the etiology of these lesions, several of the hepatic enzymes involved in activation and detoxication of PAH were studied in these two species. Hepatic aryl hydrocarbon hydroxylase (AHH), epoxide hydrolase (EH), and glutathione S-transferase (GST) activities were measured in animals sampled from both contaminated and reference areas. English sole, the species showing higher prevalences of contaminant-associated hepatic lesions, had higher (1- to 2-fold) hepatic activities of AHH and lower activities of EH (0.8-fold) and GST (1.8-fold) than those of starry flounder, regardless of site of capture. These results are largely consistent with increased activation and decreased detoxication of PAH by English sole in comparison to starry flounder. Both laboratory and field data suggested that the observed species differences in enzyme activities were constitutive and not related to differential exposure to contaminants. There were also substantial differences between these species with respect to expression of GST isoenzymes, in that starry flounder expressed two highly anionic GST isoenzymes which did not correspond to any GST isoenzymes expressed in English sole liver; a previous study in an elasmobranch fish showed that an anionic GST was most active toward PAH oxides. These differences in enzyme activities and isoenzyme profiles suggest a toxicological basis which may help to explain, at least in part, the differences in prevalences of contaminant-associated liver neoplasms between these two species.

Hepatic lesions other than neoplasms in subadult flatfish from puget sound, washington: relationships with indices of contaminant exposure

Liver neoplasms are rare in young wild fish; therefore, it is essential to consider toxicopathic liver lesions that occur earlier than neoplasms as biomarkers of contaminant exposure in studies where targeted or available fish are not adults. Also some exposure effects may be more reliably assessed in younger fish that have not yet migrated extensively. We addressed these issues by histologically examining subadult English sole, rock sole, and starry flounder captured from eight sites in Puget Sound, and by measuring fluorescent aromatic compounds (FACs) in bile and polychlorinated hiphenyls (PCBs) in liver. Neoplasms were detected rarely; higher prevalences of preneoplastic, regenerative, and degenerative lesions were detected in most species, primarily from contaminated sites, including hydropic vacuolation of hepatocytes and biliary cells in rock sole and starry flounder. These nomeoplastic lesion types are inducible in fish by exposure to various toxicants in the laboratory, and/or (in the case of hydropic vacuolation) are associated with contaminant exposure and liver neoplasia in adult wild fish. Prevalences of these ‘early’ lesions were significantly higher at the more contaminated sites, as determined by several statistical approaches, including logistic regression. Moreover, prevalences of most lesions in all three species correlated with mean bile FAC levels at the sites, and prevalences of some lesions in English sole correlated with liver PCB levels. The present findings further support the utility of certain liver lesions other than neoplasms as early indicators of biological damage in subadult as well as adult fish exposed to xenobiotics in the marine environment.

Source of harpacticoid copepods in the diet of juvenile starry flounder

Source of harpacticoid copepods in the diet of juvenile starry flounder

Overview of studies on liver carcinogenesis in English sole from Puget Sound; evidence for a xenobiotic chemical etiology II: Biochemical studies

The levels of aromatic hydrocarbons in sediments of Puget Sound, Washington, are positively correlated with the prevalence of hepatic neoplasms and related lesions in English sole (Parophrys vetulus). To investigate the biochemical processes involved in chemical carcinogenesis in fish from Puget Sound, we have studied the uptake, activation, and detoxication of polycyclic aromatic hydrocarbons (PAHs) in English sole, and have compared these data to PAH metabolism in a related species, starry flounder (Platichthys stellatus), which shows a lower prevalence of hepatic neoplasms than sole. The results of both laboratory and field studies show that sediment-associated PAHs are biologically available to both flatfish species, and that both species accumulate similar levels of PAHs. Analyses of hepatic DNA from sole using the 32P-postlabeling technique indicate that xenobiotic chemicals were adducted to hepatic DNA of fish from the contaminated sites but not to the DNA of fish from reference sites. Studies of the ability of English sole and starry flounder to metabolize benzo(a)pyrene (BaP) and bind reactive BaP intermediates to hepatic DNA indicate that biochemical differences in the metabolism of carcinogenic PAHs may explain, at least in part, the apparent lower susceptibility of starry flounder than English sole to chemically induced hepatocarcinogenesis.