cDNA cloning and cadmium-induced expression of metallothionein mRNA in the zebra mussel Dreissena polymorpha.
Using pooled degenerate oligonucleotides inferred from the N-terminal amino acid sequence of Dreissena polymorpha metallothionein and a Cys-X-Cys motif characteristic for known metallothioneins, a 150-bp metallothionein-specific reverse transcription PCR product was generated. The PCR product was used to screen a Dreissena polymorpha cDNA library, and a complete metallothionein cDNA sequence from Dreissena was identified. Four clones with the identical sequence were detected, supporting the idea of a single metallothionein gene in Dreissena. The sequence contains a 141-bp 5' untranslated region and a 572-bp 3' untranslated region with two polyadenylation signals. The coding region spans 219 bp. The deduced amino acid sequence shows 21 cysteine residues present in the metallothionein-typical motifs. Induction studies were performed with 50 microg Cd2+/L for up to 16 days. The exposed mussels show a sevenfold higher metallothionein mRNA level compared with uninduced control mussels.
Engelken
J
J
Department of Biology, University of Bremen, Germany.
Hildebrandt
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D049872:Bivalvia / Q000235:genetics*; D002104:Cadmium / Q000494:pharmacology*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005786:Gene Expression Regulation / Q000187:drug effects*; D008668:Metallothionein / Q000235:genetics*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D012333:RNA, Messenger; D002104:Cadmium; D008668:Metallothionein