title: The physiological role and toxicological significance of the non-metal-selective cadmium/copper-metallothionein isoform differ between embryonic and adult helicid snails.
abstract: Metal regulation is essential for terrestrial gastropods to survive. In helicid snails, two metal-selective metallothionein (MT) isoforms with different functions are expressed. A cadmium-selective isoform (CdMT) plays a major role in Cd2+detoxification and stress response, whereas a copper-selective MT (CuMT) is involved in Cu homeostasis and hemocyanin synthesis. A third, non-metal-selective isoform, called Cd/CuMT, was first characterized in Cantareus aspersus. The aim of this study was to quantify the transcriptional activity of all three MT genes in unexposed and metal-exposed (Cd, Cu) embryonic Roman snails. In addition, the complete Cd/CuMT mRNA of the Roman snail (Helix pomatia) was characterized, and its expression quantified in unexposed and Cd-treated adult individuals. In embryos of Helix pomatia, the Cd/CuMT gene was induced upon Cu exposure. Its transcription levels were many times higher than that of the other two MT genes, and also exceeded by far the Cd/CuMT mRNA concentrations of adult snails. In the hepatopancreas of adult Roman snails, no Cd/CuMT could be detected at the protein level, irrespective of whether the snails had been exposed to Cd or not. This contrasts with the situation in the near relative, Cantareus aspersus. It appeared that the 3'-UTR of the Cd/CuMT mRNA differed largely between Cantareus aspersus and Helix pomatia, being larger in the latter species, with a number of putative binding sites for proteins and miRNAs known to inhibit mRNA translation. We suggest this as a possible mechanism responsible for the lack of Cd/CuMT protein expression in adult Roman snails.
authors.affiliation: Department of Zoology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
authors.forename: Veronika
authors.initials: V
authors.lastname: Pedrini-Martha
authors.affiliation: Department of Zoology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
authors.forename: Raimund
authors.initials: R
authors.lastname: Schnegg
authors.affiliation: Chrono-Environnement, UMR 6249 University of Franche-Comté, 16 route de Gray, 25030 Besançon cedex, France.
authors.forename: Pierre-Emmanuel
authors.initials: PE
authors.lastname: Baurand
authors.affiliation: Chrono-Environnement, UMR 6249 University of Franche-Comté, 16 route de Gray, 25030 Besançon cedex, France; Department of Health Safety Environment, avenue des Rives du Lac, BP179, 70003 Vesoul cedex, France.
authors.forename: Annette
authors.initials: A
authors.lastname: deVaufleury
authors.affiliation: Department of Zoology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria. Electronic address: Reinhard.Dallinger@uibk.ac.at.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Dallinger
mesh_terms: D020413:3' Untranslated Regions / Q000187:drug effects; D020121:5' Untranslated Regions / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002104:Cadmium / Q000633:toxicity*; D017124:Conserved Sequence; D003300:Copper / Q000633:toxicity*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D006372:Helix, Snails / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D043143:Hepatopancreas / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D008668:Metallothionein / Q000819:agonists / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009024:Morphogenesis / Q000187:drug effects; D010063:Ovum / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D020033:Protein Isoforms / Q000819:agonists / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012989:Soil Pollutants / Q000633:toxicity*; D013045:Species Specificity
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D020033:Protein Isoforms; D012989:Soil Pollutants; C116509:cadmium-metallothionein complex; C007121:copper thionein; D002104:Cadmium; D003300:Copper; D008668:Metallothionein
keywords: 5′ and 3′UTRs; Cadmium; Cantareus aspersus; Copper; Detoxification; Development; Gastropoda; Helix pomatia; mRNA binding proteins; miRNA