Responses of Chub (Leuciscus cephalus) Populations to Chemical Stress,Assessed by Genetic Markers,DNA Damage and Cytochrome P4501A Induction |
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| Authors: | Larno Valérie Laroche Jean Launey Sophie Flammarion Patrick Devaux Alain |
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| Affiliation: | (1) Laboratoire des Sciences de l'Environnement, Ecole Nationale des Travaux Publics de l'Etat, Rue Maurice Audin, 69518 Vaulx en Velin Cedex;(2) INRA-SCRIBE, Campus de Beaulieu, 35000 Rennes Cedex, France;(3) Laboratoire d'Ecologie des Hydrosystèmes Fluviaux, UMR CNRS 5023, Université Claude Bernard Lyon I, 43 bd du 11 Novembre 1918, 69622 Villeurbanne Cedex;(4) Laboratoire Ressources Halieutiques—Poissons Marins, Institut Universitaire Européen de la Mer, Place Nicolas Copernic, 29280 Plouzané, France;(5) Laboratoire de Génétique des Poissons, INRA, 78352 Jouy en Josas, France;(6) Laboratoire d'Ecotoxicologie, Cemagref, 3 bis quai Chauveau, CP 220, 69336 Lyon Cedex 09, France |
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| Abstract: | Indicators of effects at the population level (genetic variation using allozymes) and early indicators of pollution (EROD activity and DNA strand break formation) were analysed in chub (Leuciscus cephalus) living in weakly and heavily contaminated stations of the Rhône River watershed. The genetic erosion was mainly detected in a fish population living in a contaminated small river system, through modifications in allelic and genotypic frequencies for PGM-2 locus and could be linked to a genetic bottleneck and to the reduced gene flow from upstream unable to maintain or restore the genetic diversity. In a contaminated large river system, the genetic diversity for PGM-2 and other loci was maintained and was probably the consequence of a high gene flow from upstream, linked to a sustained drift of larvae and juveniles in the system. A convergent increase of the frequency of the 90 allele at PGM-2 was observed in two contaminated stations compared with the reference station, this trend being confirmed on a more extensive geographic scale over the Rhône River basin. A high level of EROD activity was detected in both contaminated sites but only the fish in the large river system showed a significant DNA damage level compared to the reference population. The low DNA damage level and high hepato-somatic ratio characterized the impacted population of the small river system and could be associated to a chronic high-level exposure of fish to pollutants which selected individuals exhibiting a high level of DNA damage repair. In the two contaminated systems, some genotypes at the PGM-2 and EST-2 loci showed a low level of DNA damage and/or a high EROD activity and may be considered as being tolerant to pollutants. A higher tolerance of the most heterozygous fish was also detected in the contaminated large system and confirmed that a high level of heterozygosity may be necessary for survival in such a system. |
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| Keywords: | biomarkers genetic ecotoxicology fish DNA strand break EROD activity |
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