ABSTRACT
The aim of the present work was to investigate genotoxicant accumulation and biological responses of zebra mussels and blue mussels collected along a pollution gradient in the Seine estuary and in the Seine Bay. The sampling area included three contaminated and one reference sites for each species. The study focused on polyaromatic hydrocarbons (PAH), lindane, polychlorobiphenyls (PCB) and metals known to be potential genotoxicants and/or reactive oxygen species (ROS) inducers. Enzymatic activities related to cellular defence systems including the phase II enzyme glutathione S-transferase (GST) and three antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were measured in gills. DNA adducts and DNA strand breaks (Comet assay) were measured in digestive gland and hemocytes, respectively. Species differences were observed in metal accumulation (As and Pb), GPx activity and DNA adduct formation. A marked upstream-downstream gradient was reported for PAH body burden and to a lesser extent for PCB and metals with the highest values measured just downstream the industrialized area of Rouen. GST and SOD activities in gills of bivalves were positively related to PAH and metals body burden, respectively. Activation of those cellular defences may prevent accumulation of electrophilic metabolites and free radicals and thus may protect DNA and others macromolecules against oxidation and adduction. Although DNA strand breaks and bulky adducts were detected in both species, levels were relatively low and no significant site differences were observed in June 2003. Our results indicate a clear relationship between genotoxicant accumulation and positive activation of detoxification and antioxidant systems but poor consequences in term of DNA damage for wild population of mussels inhabiting the Seine estuary.
Subject(s)
Dreissena/drug effects , Enzymes/drug effects , Mytilus edulis/drug effects , Water Pollutants, Chemical/toxicity , Animals , Comet Assay/methods , DNA Adducts/drug effects , DNA Damage , Dreissena/chemistry , Environmental Exposure , France , Hexachlorocyclohexane/analysis , Hexachlorocyclohexane/toxicity , Metals/analysis , Metals/toxicity , Mytilus edulis/chemistry , Polychlorinated Biphenyls/analysis , Polychlorinated Biphenyls/toxicity , Polycyclic Aromatic Hydrocarbons/analysis , Polycyclic Aromatic Hydrocarbons/toxicity , Rivers , Water Pollutants, Chemical/analysisABSTRACT
The involvement of molecules belonging to the insulin/IGF family in regulation of growth has been investigated in the Pacific oyster Crassostrea gigas. In vitro biological effects of human recombinant IGF-1 (hrIGF-1) on mantle edge cells, involved in oyster shell and soft body growth, were studied over an annual cycle. In mantle edge cells hrIGF-1 stimulates protein synthesis of 56+/-5.1% over basal for 10(-10) M in September with in addition a clear dose-effect corresponding to the highest shell growth period, and 57.5+/-3.45% over basal for 10(-11) M in March and 51+/-5.4% over basal for 10(-10) M in April corresponding to the period of mantle growth. These insulin-like effects were associated with the expression of a recently identified C. gigas insulin receptor-related receptor (CIR) in mantle edge cells as demonstrated by RT-PCR. Moreover, in situ hybridisation (ISH) confirmed this expression at the level of the inner and outer epithelia involved in mantle growth and shell formation.
Subject(s)
Epidermis/metabolism , Insulin-Like Growth Factor I/physiology , Insulin/physiology , Ostreidae/growth & development , Receptor, Insulin/metabolism , Analysis of Variance , Animals , Base Sequence , Epidermal Cells , Epidermis/growth & development , Humans , In Vitro Techniques , Membrane Proteins , Molecular Sequence Data , Organoids/cytology , Organoids/metabolism , Ostreidae/cytology , Ostreidae/metabolism , Protein Biosynthesis , RNA, Messenger/analysis , Receptor, Insulin/genetics , Recombinant Proteins , Reverse Transcriptase Polymerase Chain Reaction , SeasonsABSTRACT
A full-length cDNA encoding a 72 kDa heat shock cognate protein (Hsc72) was isolated from a Crassostrea gigas hemocyte library. This cDNA is 75% identical to a human hsc70 cDNA. C. gigas cDNA contains a 659 amino acid open reading frame encoding a 72 kDa protein which is 87% identical to a human Hsc70 protein. Northern blotting indicated that even if the hsc72 gene was constitutively expressed in oyster hemocytes, it could be stimulated by heat shock in vitro as well as in vivo. Homologies observed both at the cDNA and protein levels, as well as the expression pattern of the hsc72 mRNA, support our conclusion that the isolated cDNA clone corresponds to an oyster heat shock cognate gene.
