Metal distribution and metallothionein induction after cadmium exposure in the terrestrial snail Helix aspersa (Gastropoda, Pulmonata).
The aim of the present work was to study the effect of Cd2+ exposure on metallothionein (MT) induction and on the distribution of metals (Cd, Cu, and Zn) in the terrestrial pulmonate Helix aspersa. In particular, the soluble and nonsoluble pools of the accumulated metals and their tissue distribution in uncontaminated and contaminated edible snails were investigated after a two-week exposure to Cd2+. In the soluble cytosolic pool of the midgut gland of H. aspersa, three metal-specific putative MT isoforms were separated following a fractionation protocol with diethylaminoethyl cellulose, size-exclusion chromatography, ultrafiltration, and reversed-phase high-performance liquid chromatography (RP-HPLC). Interestingly, one of the above isoforms seems to bind both Cd and Cu, which may in addition mobilize, after induction by Cd2+, some of the intracellular Cu and, thus, perhaps increase the Cu pool in the cytosolic fraction. The cDNA and its translated amino acid sequence of a Cd2+-binding MT isoform from the snail midgut gland was characterized and attributed to one of the putative MT isoforms obtained by RP-HPLC. The amino acid sequence of this Cd-MT isoform of H. aspersa differed from similar sequences described in other terrestrial pulmonates, such as Helix pomatia or Arianta arbustorum, by only a few amino acids (n = 4 and 8, respectively). That the identified Cd-MT from H. aspersa is inducible by Cd2+ also was shown, chromatographic evidence aside, by a specific polymerase chain reaction protocol on a cDNA basis, which included a noninducible housekeeping gene as a control.
Hispard
Florian
F
University of Franche-Comté, Department of Chrono-Environment, Mixed Research Unit 6249, University of Franche-Comté, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Place Leclerc, 25030 Besançon Cedex, France.
Schuler
Dietmar
D
de Vaufleury
Annette
A
Scheifler
Renaud
R
Badot
Pierre-Marie
PM
Dallinger
Reinhard
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002104:Cadmium / Q000032:analysis / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000032:analysis / Q000378:metabolism; D003636:DEAE-Cellulose / Q000737:chemistry; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004587:Electrophoresis, Agar Gel; D006372:Helix, Snails / Q000187:drug effects* / Q000378:metabolism; D008668:Metallothionein / Q000032:analysis / Q000378:metabolism*; D019216:Metals, Heavy / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D020033:Protein Isoforms / Q000032:analysis / Q000378:metabolism; D012469:Salivary Glands / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D012995:Solubility; D013997:Time Factors; D014018:Tissue Distribution; D014462:Ultrafiltration; D015032:Zinc / Q000032:analysis / Q000378:metabolism
D018076:DNA, Complementary; D019216:Metals, Heavy; D020033:Protein Isoforms; D002104:Cadmium; D003300:Copper; D003636:DEAE-Cellulose; D008668:Metallothionein; D015032:Zinc