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Stephen G. George - One of the best experts on this subject based on the ideXlab platform.
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transcriptomic responses of european flounder Platichthys flesus liver to a brominated flame retardant mixture
Aquatic Toxicology, 2013Co-Authors: Tim D. Williams, Amer Diab, Matt Gubbins, Catherine Collins, Iveta Matejusova, Rose C Kerr, J K Chipman, Raoul Kuiper, Dick A Vethaak, Stephen G. GeorgeAbstract:Male European flounder (Platichthys flesus) were exposed to a technical mixture of brominated diphenyl ethers (PDBEs, DE-71, Pentamix) that had been purified to remove contaminating dioxins. Controls were exposed to carrier solvent alone. Fish were exposed to decadally increasing concentrations of Pentamix via both sediment and spiked food. The GENIPOL P. flesus cDNA microarray, differentially expressed gene profiling (DEG) and quantitative PCR were employed to detect hepatic transcriptional differences between exposed fish and controls. Gene transcriptional changes were more sensitive to Pentamix exposure than biomarkers measured previously. Pentamix exposure induced transcripts coding for enzymes of xenobiotic metabolism (CYP1A, aldo-keto reductases) and elicited endocrine disruption (vitellogenin and thyroid hormone receptor alpha), with effects on CYP1A and VTG occurring at the highest exposure. Ontology analysis clearly showed dose-responsive changes indicative of oxidative stress, induction of mitochondrial dysfunction, and apoptosis. We conclude that exposure to PBDEs in both sediment and food has a significant adverse effect on a broad range of crucial biochemical processes in the livers of this widely distributed estuarine fish species, the flounder.
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Transcriptomic responses of European flounder (Platichthys flesus) to model toxicants.
Aquatic toxicology (Amsterdam Netherlands), 2008Co-Authors: Tim D. Williams, J. Kevin Chipman, Amer Diab, Victoria Sabine, Fernando Ortega, Rita E. Godfrey, Francesco Falciani, Stephen G. GeorgeAbstract:Abstract The temporal transcriptomic responses in liver of Platichthys flesus to model environmental pollutants were studied over a 16-day time span after intraperitoneal injection with cadmium chloride (50 μg/kg in saline), 3-methylcholanthrene (25 mg/kg in olive oil), Aroclor 1254 (50 mg/kg in olive oil), tert -butyl-hydroperoxide (5 mg/kg in saline), Lindane (25 mg/kg in olive oil), perfluoro-octanoic acid (100 mg/kg in olive oil) and their vehicles, olive oil (1 ml/kg) or saline (0.9%). Statistical, gene ontology and supervised analysis clearly demonstrated the progression from acute effects, biological responses to and recovery from the treatments. Key biological processes disturbed by the individual treatments were characterised by gene ontology analyses and individual toxicant-responsive genes and pathways were identified by supervised analyses. Responses to the polyaromatic and chlorinated aromatic compounds showed a degree of commonality but were distinguishable and they were clearly segregated from the responses to the pro-oxidants cadmium and the organic hydroperoxide, as well as from the peroxisomal proliferator, perfluoro-octanoic acid. This study demonstrated the utility of the microarray technique in the identification of toxicant-responsive genes and in discrimination between modes of toxicant action.
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Adaptive differences in gene expression in European flounder (Platichthys flesus).
Molecular ecology, 2007Co-Authors: Peter Foged Larsen, J. Kevin Chipman, Einar Eg Nielsen, Tim D. Williams, Jakob Hemmer-hansen, Mogens Kruhøffer, Peter Grønkjær, Stephen G. George, Lars Dyrskjøt, Volker LoeschckeAbstract:Population structure was previously believed to be very limited or absent in classical marine fishes, but recently, evidence of weakly differentiated local populations has been accumulating using noncoding microsatellite markers. However, the evolutionary significance of such minute genetic differences remains unknown. Therefore, in order to elucidate the relationship between genetic markers and adaptive divergence among populations of marine fishes, we combined cDNA microarray and microsatellite analysis in European flounders (Platichthys flesus). We demonstrate that despite extremely low levels of neutral genetic divergence, a high number of genes were significantly differentially expressed between North Sea and Baltic Sea flounders maintained in a long-term reciprocal transplantation experiment mimicking natural salinities. Several of the differentially regulated genes could be directly linked to fitness traits. These findings demonstrate that flounders, despite little neutral genetic divergence between populations, are differently adapted to local environmental conditions and imply that adaptation in gene expression could be common in other marine organisms with similar low levels of population subdivision.
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Gene expression responses of European flounder (Platichthys flesus) to 17-β estradiol
Toxicology letters, 2006Co-Authors: Timothy Williams, Stephen G. George, Amer Diab, Victoria Sabine, James K. ChipmanAbstract:Male European flounder (Platichthys flesus) were intraperitoneally injected with 10mg/kg 17-beta estradiol and tissues taken from individuals over a timecourse of 16 days. The GENIPOL P. flesus cDNA microarray was employed to detect hepatic gene expression differences between fish treated with estradiol and saline controls. Known biomarkers of estrogen exposure, choriogenin L and vitellogenins, showed sustained induction over the time-course. Among 175 identified clones showing sustained statistically significant induction or repression, those associated with the Gene Ontology terms mitochondria, amino acid synthesis, ubiquitination and apoptosis were included amongst those induced while those associated with immune function, electron transport, cell signalling and protein phosphorylation were repressed. Thus, we show the gene expression response of an environmentally relevant fish species to a high dose of an estrogenic endocrine disruptor and also report the sequencing of a further 2121 flounder ESTs.
Thomas Lang - One of the best experts on this subject based on the ideXlab platform.
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Screening of hydrophobic DNA adducts in flounder (Platichthys flesus) from the Baltic Sea
Chemosphere, 2009Co-Authors: Chira Malmström, Thomas Lang, M. Konn, Sergei Bogovski, L.-g. Lönnström, G. BylundAbstract:Neoplasia and other histopathological lesions in flounder (Platichthys flesus) liver have been investigated in several European sea areas, including the Baltic Sea. Several studies have been able to link neoplasm epizootics in fish with the exposure to genotoxins such as polycyclic aromatic hydrocarbons (PAHs). The level of hydrophobic DNA adducts in tissue DNA reflects the exposure of the organism to PAHs. Using hydrophobic DNA adduct levels as biomarkers, possible PAH exposure was assessed in flounder from 10 different sites in the Baltic Sea, collected during the years 1995-1997. The results show that the overall levels of hepatic DNA adducts were low and, in general, the chromatograms appeared clean. The highest levels of DNA adducts were found at two sites in the southern Baltic Sea. There were no statistically significant differences in adduct levels between the sites. Our results indicate that flounder from studied off shore sites of the Baltic Sea had not been exposed to a greater extent to large polycyclic hydrophobic hydrocarbons in their environment.
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Liver histopathology in Baltic flounder (Platichthys flesus) as indicator of biological effects of contaminants.
Marine pollution bulletin, 2006Co-Authors: Thomas Lang, Werner Wosniok, Janina Barsiene, Katja Broeg, Justyna Kopecka, Jari ParkkonenAbstract:Results are presented of a study on liver histopathology in Baltic flounder (Platichthys flesus) carried out in 2001 and 2002 in four coastal sampling areas of the Baltic Sea: Kvädöfjärden (Swedish east coast, reference area), Klaipeda-Butinge (Lithuanian coast), Gulf of Gdansk (Polish coast), and Wismar Bay (German coast) within the framework of the EU-funded BEEP project. Liver lesions were diagnosed and categorised using standardised methodologies and, for a spatial and temporal assessment of the prevalence and types of lesions detected, a scoring system was applied, involving the calculation of mean histopathology lesion scores. 83.0% of the 436 female flounder examined (size range: 20-43 cm total length, age range: 2-8 years) were affected by liver lesions, out of which 74.3% were assigned to the category of non-specific, 3.4% to the category of early toxicopathic non-neoplastic, 4.6% to the category of pre-neoplastic and 0.7% to the category of neoplastic lesions. Mean lesions scores were highest in the areas at the Lithuanian and Swedish coast and there is indication of an impact of the age structure of the flounder populations studied, the sampling season as well as of contaminant effects.
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Geographical variation in the age/length relationship in Baltic flounder (Platichthys flesus)
ICES Journal of Marine Science, 1999Co-Authors: Tonno Drevs, Vello Kadakas, Thomas Lang, Stig MellergaardAbstract:The age/length relationship in Baltic flounder (Platichthys flesus) was investigated by sex, based on otolith readings of 2925 individuals sampled from 11 stations along a transect from the Mecklenburg Bight to the Gulf of Finland in autumn 1994. A significant decrease in length at age was observed from the southwestern to the northeastern areas. However, with advancing age the differences in length became less pronounced. The size differences between sexes increased markedly with advancing age.
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Short communication Geographical variation in the age/length relationship in Baltic flounder (Platichthys flesus)
1999Co-Authors: Tonno Drevs, Vello Kadakas, Thomas Lang, Stig MellergaardAbstract:The age/length relationship in Baltic flounder (Platichthys flesus) was investigated by sex, based on otolith readings of 2925 individuals sampled from 11 stations along a transect from the Mecklenburg Bight to the Gulf of Finland in autumn 1994. A significant decrease in length at age was observed from the southwestern to the northeastern areas. However, with advancing age the diVerences in length became less pronounced. The size diVerences between sexes increased markedly with advancing age. ? 1999 International Council for the Exploration of the Sea
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Spatial distribution of grossly visible diseases and parasites in flounder (Platichthys flesus) from the Baltic Sea: a synoptic survey
ICES Journal of Marine Science, 1999Co-Authors: Thomas Lang, Vello Kadakas, Stig Mellergaard, Werner Wosniok, K. NeumannAbstract:Information on prevalences of grossly visible diseases and parasites of flounder (Platichthys flesus) from the Baltic Sea is presented for 11 sampling areas on a transect from the Mecklenburg Bight to the Gulf of Finland. Among the 3008 flounder examined, highest overall prevalences were observed for lymphocystis (14.4%) and acute/healing stages of the skin ulcer disease (5.9%). The prevalences of liver neoplasms >2 mm in diameter (0.4%), skeletal deformities (0.6%), and fin rot/erosion (0.5%) were low. The only externally visible parasite recorded was Cryptocotyle concavum (28.2%). The results of a multivariate statistical analysis reveal that the diseases are influenced by a variety of host-specific (length, age, sex) and area-specific (salinity, temperature) factors as well as their interactions. By calculating the expected prevalence for a standardized fish population for each area and disease, the extent of area-specific effects not attributable to host-specific factors was estimated.
Jean Laroche - One of the best experts on this subject based on the ideXlab platform.
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New set of candidate gene SNPs and microsatellites to disentangle selective and neutral processes shaping population responses of European flounder (Platichthys flesus) to anthropogenic stress and contrasted environments
Conservation Genetics Resources, 2015Co-Authors: Nicolas Pédron, Jean Laroche, Romain Morvezen, Alan Le Moan, Bruno Guinand, Jose-luis Zambonino-infante, Grégory CharrierAbstract:Six candidate gene SNP assays and 12 new microsatellites were developed in the European flounder (Platichthys flesus), in order to provide new tools to (1) further investigate signatures of selection suspected on candidate genes, and (2) better depict the neutral evolutionary background shaping the differentiation of populations. All markers were successfully tested in two populations from contrasted estuaries, and should be helpful to better understand the possible adaptive responses of flounder populations to anthropogenic pressures (e.g. global warming, eutrophication, pollutions), over the whole distribution range of the species.
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Proteomic analysis of the European flounder Platichthys flesus response to experimental PAH-PCB contamination.
Marine pollution bulletin, 2015Co-Authors: Claire Galland, Louis Quiniou, Jean Laroche, Célie Dupuy, Véronique Loizeau, Morgane Danion, Michel Auffret, Vianney PichereauAbstract:Abstract Platichthys flesus is often used as a sentinel species to monitor the estuarine water quality. In this study, we carried out an experimental contamination of fish using a PAHs/PCBs mixture, which was designed to mimic the concentrations found in the Seine estuary (C1) and 10 times these concentrations (C2). We used a proteomic approach to understand the molecular mechanisms implied in the response of P. flesus to these xenobiotics. We showed that 54 proteins were differentially accumulated in one or several conditions, which 34 displayed accumulation factors higher than two. 18 of these proteins were identified by MALDI TOF–TOF mass spectrometry. The results indicated the deregulation of oxidative stress- and glutathione metabolism-(GST, GPx) proteins as well as of several proteins belonging to the betaine demethylation pathway and the methionine cycle (BHMT, SHMT, SAHH), suggesting a role for these different pathways in the P. flesus response to chemical contamination.
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Proteomic analysis of the European flounder Platichthys flesus response to experimental PAH–PCB contamination
Marine Pollution Bulletin, 2015Co-Authors: Claire Galland, Louis Quiniou, Jean Laroche, Célie Dupuy, Véronique Loizeau, Morgane Danion, Michel Auffret, Vianney PichereauAbstract:Platichthys flesus is often used as a sentinel species to monitor the estuarine water quality. In this study, we carried out an experimental contamination of fish using a PAHs/PCBs mixture, which was designed to mimic the concentrations found in the Seine estuary (C1) and 10 times these concentrations (C2). We used a proteomic approach to understand the molecular mechanisms implied in the response of P. flesus to these xenobiotics. We showed that 54 proteins were differentially accumulated in one or several conditions, which 34 displayed accumulation factors higher than two. 18 of these proteins were identified by MALDI TOF-TOF mass spectrometry. The results indicated the deregulation of oxidative stress- and glutathione metabolism-(GST, GPx) proteins as well as of several proteins belonging to the betaine demethylation pathway and the methionine cycle (BHMT, SHMT, SAHH), suggesting a role for these different pathways in the P. flesus response to chemical contamination.
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Comparisons of liver proteomes in the European flounder Platichthys flesus from three contrasted estuaries
Journal of Sea Research, 2013Co-Authors: Claire Galland, Louis Quiniou, Jean Laroche, Michel Auffret, Cécile Dupuy, Carole Capitaine, Vianney PichereauAbstract:Estuaries are important areas highly susceptible to anthropogenic degradations like pollution. Estuarine species have thus to cope with many types of constraints depending on the estuaries' characteristics. The European flounder Platichthys flesus is considered as a sentinel species for the monitoring of estuarine water quality. In this study, juvenile flounders (0+ group) were sampled from three contrasted Channel estuaries, i.e. the Seine, the Canche and the Tamar, and we characterized their liver proteomes by using a two-dimensional electrophoresis based proteomic approach. We showed that 27 protein spots differentially accumulated between the 3 populations. Six of these proteins were identified by MALDI TOF-TOF mass spectrometry. Flounders from the Seine and from the Tamar, two highly polluted estuaries, displayed common differences, i.e. an increase of the energetic- and the glutathione-metabolism. The most accumulated protein in the Seine's samples (6.7-fold) was a Vitelline Membrane Outer layer protein 1 homolog, suggesting oogenesis deregulation in these juvenile (sexually immature) flounders. Future works applying this kind of proteomic approach on flounders experimentally exposed to conditions that mimic environmental constraints will help to better understand the significance of these environmental proteomic signatures.
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Responses of juvenile European flounder (Platichthys flesus) to multistress in the Vilaine estuary, during a 6-month survey
Environmental Science and Pollution Research, 2013Co-Authors: Estérine Evrard, Louis Quiniou, Alain Devaux, Sylvie Bony, Jerome Cachot, Grégory Charrier, Jean LarocheAbstract:Physiological and genetic responses of age 0+ Platichthys flesus were investigated in the eutrophicated and moderately contaminated Vilaine estuary, during a 6-month survey. The main objective of this study was to explore the biological responses of fishes during their juvenile period in an estuarine system in order to detect a possible selective pressure induced by the environmental stress. Our results showed a general convergence in physiological responses along the survey: an increase in genotoxicity was associated with an increase in mRNA expression of ATPase and betaine homocysteine methyltransferase. These results could suggest an increase of cellular damage, energetic request, and detoxification rate related to the growing exposure time to stress. Considering the aging of the cohort, the genetic characteristics of the Vilaine flounder cohort came closer to the one observed in a highly stressed system, the Seine estuary, suggesting a potential selective pressure mainly induced by the chemical stress.
Tim D. Williams - One of the best experts on this subject based on the ideXlab platform.
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transcriptomic responses of european flounder Platichthys flesus liver to a brominated flame retardant mixture
Aquatic Toxicology, 2013Co-Authors: Tim D. Williams, Amer Diab, Matt Gubbins, Catherine Collins, Iveta Matejusova, Rose C Kerr, J K Chipman, Raoul Kuiper, Dick A Vethaak, Stephen G. GeorgeAbstract:Male European flounder (Platichthys flesus) were exposed to a technical mixture of brominated diphenyl ethers (PDBEs, DE-71, Pentamix) that had been purified to remove contaminating dioxins. Controls were exposed to carrier solvent alone. Fish were exposed to decadally increasing concentrations of Pentamix via both sediment and spiked food. The GENIPOL P. flesus cDNA microarray, differentially expressed gene profiling (DEG) and quantitative PCR were employed to detect hepatic transcriptional differences between exposed fish and controls. Gene transcriptional changes were more sensitive to Pentamix exposure than biomarkers measured previously. Pentamix exposure induced transcripts coding for enzymes of xenobiotic metabolism (CYP1A, aldo-keto reductases) and elicited endocrine disruption (vitellogenin and thyroid hormone receptor alpha), with effects on CYP1A and VTG occurring at the highest exposure. Ontology analysis clearly showed dose-responsive changes indicative of oxidative stress, induction of mitochondrial dysfunction, and apoptosis. We conclude that exposure to PBDEs in both sediment and food has a significant adverse effect on a broad range of crucial biochemical processes in the livers of this widely distributed estuarine fish species, the flounder.
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Transcriptomic responses of European flounder (Platichthys flesus) to model toxicants.
Aquatic toxicology (Amsterdam Netherlands), 2008Co-Authors: Tim D. Williams, J. Kevin Chipman, Amer Diab, Victoria Sabine, Fernando Ortega, Rita E. Godfrey, Francesco Falciani, Stephen G. GeorgeAbstract:Abstract The temporal transcriptomic responses in liver of Platichthys flesus to model environmental pollutants were studied over a 16-day time span after intraperitoneal injection with cadmium chloride (50 μg/kg in saline), 3-methylcholanthrene (25 mg/kg in olive oil), Aroclor 1254 (50 mg/kg in olive oil), tert -butyl-hydroperoxide (5 mg/kg in saline), Lindane (25 mg/kg in olive oil), perfluoro-octanoic acid (100 mg/kg in olive oil) and their vehicles, olive oil (1 ml/kg) or saline (0.9%). Statistical, gene ontology and supervised analysis clearly demonstrated the progression from acute effects, biological responses to and recovery from the treatments. Key biological processes disturbed by the individual treatments were characterised by gene ontology analyses and individual toxicant-responsive genes and pathways were identified by supervised analyses. Responses to the polyaromatic and chlorinated aromatic compounds showed a degree of commonality but were distinguishable and they were clearly segregated from the responses to the pro-oxidants cadmium and the organic hydroperoxide, as well as from the peroxisomal proliferator, perfluoro-octanoic acid. This study demonstrated the utility of the microarray technique in the identification of toxicant-responsive genes and in discrimination between modes of toxicant action.
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Adaptive differences in gene expression in European flounder (Platichthys flesus).
Molecular ecology, 2007Co-Authors: Peter Foged Larsen, J. Kevin Chipman, Einar Eg Nielsen, Tim D. Williams, Jakob Hemmer-hansen, Mogens Kruhøffer, Peter Grønkjær, Stephen G. George, Lars Dyrskjøt, Volker LoeschckeAbstract:Population structure was previously believed to be very limited or absent in classical marine fishes, but recently, evidence of weakly differentiated local populations has been accumulating using noncoding microsatellite markers. However, the evolutionary significance of such minute genetic differences remains unknown. Therefore, in order to elucidate the relationship between genetic markers and adaptive divergence among populations of marine fishes, we combined cDNA microarray and microsatellite analysis in European flounders (Platichthys flesus). We demonstrate that despite extremely low levels of neutral genetic divergence, a high number of genes were significantly differentially expressed between North Sea and Baltic Sea flounders maintained in a long-term reciprocal transplantation experiment mimicking natural salinities. Several of the differentially regulated genes could be directly linked to fitness traits. These findings demonstrate that flounders, despite little neutral genetic divergence between populations, are differently adapted to local environmental conditions and imply that adaptation in gene expression could be common in other marine organisms with similar low levels of population subdivision.
Frank B. Jensen - One of the best experts on this subject based on the ideXlab platform.
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Uptake and effects of nitrite in the marine teleost fish Platichthys flesus
Aquatic Toxicology, 2000Co-Authors: Martin Grosell, Frank B. JensenAbstract:The route of NO2 uptake and subsequent physiological effects were examined in the marine teleost, European flounder (Platichthys flesus), during exposure to 1 mM ambient NO2 for up to 11 days. Drinking of seawater resulted in a similar nitrite concentration in the anterior part of the intestine as in the ambient water. The NO2 concentration decreased along the gastro-intestinal tract, suggesting NO2 uptake across the intestinal epithelium. Comparison of NO2 uptake in fish that drank NO2 -contaminated seawater with fish that did not (i.e. had the intestine perfused with aN O 2 -free saline during NO2 exposure) revealed that the intestinal route contributed some 66% of whole-body NO2 uptake. Plasma [NO2 ] stayed below the ambient level. It reached a maximum of 0.35‐0.4 mM on days 3‐6 and then declined to 0.2 mM on day 11. The physiological effects of NO2 exposure were relatively minor compared with those reported in freshwater fish. Blood methemoglobin levels increased from approximately 4% in non-exposed fish to a maximum of 18% of total hemoglobin in exposed fish. An extracellular hyperkalemia was observed from day 3o f NO 2 exposure, with a maximal increase in plasma K concentrations of 38%. No mortality occurred during the 11 days of NO2 exposure. The lack of mortality can be related to the relatively low NO2 accumulation in the plasma and the relatively minor physiological disturbances. © 2000 Elsevier Science B.V. All rights reserved.