title: Differential expression of metallothionein isoforms in terrestrial snail embryos reflects early life stage adaptation to metal stress.
abstract: The aim of this study was to analyze the expression of three metallothionein (MT) isoform genes (CdMT, CuMT and Cd/CuMT), already known from adults, in the Early Life Stage (ELS) of Cantareus aspersus. This was accomplished by detection of the MT isoform-specific transcription adopting Polymerase Chain Reaction (PCR) amplification and quantitative Real Time (qRT)-PCR of the three MT genes. Freshly laid eggs were kept for 24 hours under control conditions or exposed to three cadmium (Cd) solutions of increasing concentration (5, 10, and 15 mg Cd/L). The transcription of the three MT isoform genes was detected via PCR in 1, 6 and 12-day-old control or Cd-exposed embryos. Moreover, the transcription of this isoform genes during development was followed by qRT-PCR in 6 and 12-day-old embryos. Our results showed that the CdMT and Cd/CuMT genes, but not the CuMT gene, are expressed in embryos at the first day of development. The transcription of the 3 MT genes in control embryos increased with development time, suggesting that the capacities of metal regulation and detoxification may have gradually increased throughout embryogenesis. However in control embryos, the most highly expressed MT gene was that of the Cd/CuMT isoform, whose transcription levels greatly exceeded those of the other two MT genes. This contrasts with the minor significance of this gene in adult snails and suggests that in embryos, this isoform may play a comparatively more important role in metal physiology compared to adult individuals. This function in adult snails appears not to be related to Cd detoxification. Instead, snail embryos responded to Cd exposure by over-expression of the CdMT gene in a concentration-dependent manner, whereas the expression of the Cd/CuMT gene remained unaffected. Moreover, our study demonstrates the ability of snail embryos to respond very early to Cd exposure by up-regulation of the CdMT gene.
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: Institute of Zoology, University of Innsbruck, Technikerstraße 25, A-6020, Innsbruck, Austria.
authors.forename: Veronika
authors.initials: V
authors.lastname: Pedrini-Martha
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: de Vaufleury
authors.affiliation: Institute of Zoology, University of Innsbruck, Technikerstraße 25, A-6020, Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Niederwanger
authors.affiliation: Chrono-Environnement, UMR 6249 University of Franche-Comté, 16 route de Gray, 25030, Besançon cedex, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Capelli
authors.affiliation: Chrono-Environnement, UMR 6249 University of Franche-Comté, 16 route de Gray, 25030, Besançon cedex, France.
authors.forename: Renaud
authors.initials: R
authors.lastname: Scheifler
authors.affiliation: Institute of Zoology, University of Innsbruck, Technikerstraße 25, A-6020, Innsbruck, Austria.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Dallinger
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics*; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006372:Helix, Snails / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D020033:Protein Isoforms; D002104:Cadmium; D008668:Metallothionein