title: cDNA cloning and gene expression of ribosomal S9 protein gene in the mollusk Corbicula fluminea: a new potential biomarker of metal contamination up-regulated by cadmium and repressed by zinc.
abstract: Biological indicators can be used to assess polluted sites, but their success depends on their specificity. The aim of the present study was to identify a specific cadmium biomarker of the freshwater bivalve Corbicula fluminea. Differential display technique was used to identify new molecular indicators for cadmium exposure. Gene expression of C. fluminea transplanted into a cadmium- and zinc-contaminated river was compared to gene expression of bivalves from a reference site. One differentially expressed band was identified, and the entire cDNA sequence coding for the ribosomal protein S9 (rpS9) was cloned. The rpS9 gene expression was studied by real-time reverse transcription-polymerase chain reaction. After controlled cadmium (15 microg/L) and/or zinc (1 mg/L) laboratory contaminations of the bivalves, this gene was shown to be up-regulated by cadmium and down-regulated by zinc. A 48-d transplantation of animals into a polymetallic field contamination in the Lot river basin (Midi-Pyrénées region, France) showed that rpS9 gene regulation was correlated with the fluctuating cadmium and zinc water contents. To our knowledge, the existence of a gene that is up-regulated by cadmium and repressed by zinc is demonstrated here for the first time.
authors.affiliation: Laboratoire d'Ecophysiologie et d'Ecotoxicologie des Systèmes Aquatiques (LEESA), Universite Bordeaux I/UMR CNRS 5805, Place du Dr. Peyneau, 33120 Arcachon, France.
authors.forename: Maud
authors.initials: M
authors.lastname: Achard-Joris
authors.forename: Patrice
authors.initials: P
authors.lastname: Gonzalez
authors.forename: Véronique
authors.initials: V
authors.lastname: Marie
authors.forename: Magalie
authors.initials: M
authors.lastname: Baudrimont
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Bourdineaud
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015415:Biomarkers; D002104:Cadmium / Q000633:toxicity*; D003001:Cloning, Molecular; D049874:Corbicula / Q000235:genetics* / Q000502:physiology; D015536:Down-Regulation; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000091243:Ribosomal Protein S9; D012269:Ribosomal Proteins / Q000096:biosynthesis*; D012680:Sensitivity and Specificity; D015854:Up-Regulation / Q000187:drug effects; D015032:Zinc / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D000091243:Ribosomal Protein S9; D012269:Ribosomal Proteins; D002104:Cadmium; D015032:Zinc