Seasonal changes in mRNA encoding for cell stress markers in the oyster Crassostrea gigas exposed to radioactive discharges in their natural environment

• Published in: Science of The Total Environment
• Main Authors: Farcy, E., Voiseux, C., Lebel, J.-M., Fiévet, B.
• Other Authors: Laboratoire de Radioécologie de Cherbourg-Octeville (IRSN/PSE-ENV/SRTE/LRC), Service de recherche sur les transferts et les effets des radionucléides sur les écosystèmes (IRSN/PSE-ENV/SRTE), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: Animal cell culture; Environmental protection; Genes; Marine engineering; Radioactive wastes; RNA; Crassostrea gigas; Heat shock proteins; Metallothionein; mRNA; Radioactive discharges; Seasonal variations; Superoxide dismutase; Climate change; heat shock protein 70; heat shock protein 72; heat shock protein 90; messenger RNA; biomarker; bivalve; discharge; gene expression; marine environment; pollution effect; pollution exposure; radioactive waste; radioactivity; radionuclide; seasonal variation; article; atmospheric radioactivity; biota; cell stress; correlation analysis; evaluation; France; liquid; nonhuman; oyster; priority journal; protein expression; real time polymerase chain reaction; season; Animals; Biological Markers; Crassostrea; Environmental Monitoring; Areva
• Online Access: https://hal.science/hal-03008517; https://doi.org/10.1016/j.scitotenv.2006.11.014

The North Cotentin area (Normandy, France) hosts several nuclear facilities among which the AREVA reprocessing plant of La Hague is responsible for controlled discharges of liquid radioactive wastes into the marine environment. The resulting increase in radioactivity is very small compared to natural radioactivity. However, concerns about environment protection prompted the scientific community to focus on the effects of the chronic exposure to low concentrations of radionuclides in non-human biota. This study contributes to the evaluation of the possible impact of radioactive discharges on the oyster Crassostrea gigas in the field. Real-time polymerase chain reaction was used to quantify the expression levels of genes involved in cell stress in the oyster. They included members of the heat shock protein family (Hsp70, Hsc72, Hsp90), superoxide dismutase (SOD) and metallothionein (MT). Times series measurements were built from periodic samplings in the natural environment in order to characterize the natural variability as well as possible seasonal fluctuations. The genes studied exhibited a general seasonal expression pattern with a peak value in winter. The data inversely correlated with seawater temperature and the nature of the relationship between gene expression and temperature is discussed. In parallel, oysters were collected in four locations on the French shores, exposed or not to radioactive liquid wastes from the nuclear facilities hosted in the North Cotentin. The comparison of data obtained in the reference location on the Atlantic coast (not exposed) and data from oysters of the English Channel (exposed) gave no evidence for any statistical difference. However, because of the complexity of the natural environment, we cannot rule out the possibility that other parameters may have masked the impact of radioactive discharges. This dense set of data is a basis for the use of the expression levels of those genes as biomarkers to address the question of the possible effects of chronic exposure of the ...