Potential use of the levels of the mRNA of a specific metallothionein isoform (MT-20) in mussel (Mytilus edulis) as a biomarker of cadmium contamination.
Metallothionein (MT) is a metal-inducible protein and a potential biomarker of metal pollution. Mussel MTs are characterized by having both monomeric (MT-10) and dimeric (MT-20) isoforms. We have carried out a series of experiments in which we studied mRNA levels of both MTs in Mytilus edulis after a brief exposure (6-72 h) to cadmium, zinc and copper. The induction of MT-10 and MT-20 mRNA in the heavy metal-treated mussels was detected by Northern blot analysis. The exposure of mussels to copper (40 microgl(-1)), cadmium (200 microgl(-1)) or zinc (1,000 microgl(-1)) resulted in different MT-gene induction patterns. In the cadmium-intoxicated mussels levels of both MT-10 and MT-20 mRNA were increased. In the zinc-treated mussels, a rapid response of the MT-10 gene was detected within 6 h. Induction of MT-20 transcription was specific for cadmium, and can be envisaged as a potential biomarker of cadmium contamination. Copper had no effect on mRNA levels. We suggest the possibility that there is a hitherto-unknown copper-specific isoform.
Soazig
Lemoine
L
Laboratoire de Biologie Marine, Faculté des Sciences, Université des Antilles et de la Guyane UAG, DYNECAR, Campus de Fouillole, 97110 Pointe à Pitre, Guadeloupe, France. soazig.lemoine@univ-ag.fr
Marc
Laulier
L
D000818:Animals; D049872:Bivalvia / Q000235:genetics*; D015152:Blotting, Northern; D002104:Cadmium / Q000378:metabolism*; D003300:Copper / Q000378:metabolism; D005786:Gene Expression Regulation; D008668:Metallothionein / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics*; D015533:Transcriptional Activation; D015032:Zinc / Q000378:metabolism
D020033:Protein Isoforms; D012333:RNA, Messenger; D002104:Cadmium; D003300:Copper; D008668:Metallothionein; D015032:Zinc