MEPS 200:149-157 (2000)  -  doi:10.3354/meps200149

Purification, cDNA cloning and expression of a cadmium-inducible cysteine-rich metallothionein-like protein from the marine sponge Suberites domuncula

Heinz C. Schröder1, Kateryna Shostak1,2, Vera Gamulin3, Markus Lacorn4, Alexander Skorokhod1,2, Vadim Kavsan2, Werner E. G. Müller1,*

1Abteilung Angewandte Molekularbiologie, Institut für Physiologische Chemie, Universität Mainz, Duesbergweg 6, 55099 Mainz, Germany
2Department of Biosynthesis of Nucleic Acids, Ukrainian Academy of Sciences, Institute of Molecular Biology and Genetics, 252627 Kiev, Ukraine
3Department of Molecular Genetics, Institute Rudjer Boskovic, 10000 Zagreb, Croatia
4Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany
*Corresponding author. E-mail:

ABSTRACT: During the last few years sponges have been proven to be suitable model organisms for biomonitoring programmes. Previously it was reported that the marine sponge Suberites domuncula reacts to cadmium, both under controlled laboratory conditions and in the field with an increased expression of the heat-shock protein 70 and with DNA damage. In this study it is shown that this sponge contains a cadmium-binding protein with a Mr of 24000. Cloning studies detected a gene in S. domuncula, termed SDMTL, which encodes a putative polypeptide, MTL_SUBDO, that shares high sequence similarity with metallothioneins (MTs) from Metazoa. The open reading frame displays a polypeptide with a calculated size of Mr of 17103. Phylogenetic analysis revealed that the sponge molecule, termed MT-like (MTL) protein, is related to the metazoan MTs. Under laboratory conditions, no expression of the SDMTL can be detected. After 1 d, incubation of the sponges with cadmium (200 µg l-1) already revealed a dramatic upregulation of the MTL gene in S. domuncula. Subsequent studies in the field, the area around Rovinj (Croatia), demonstrated a correlation between the environmental load with cadmium (accumulation of this metal in the animals) and the expression of the gene encoding the Œdetoxifying¹ cadmium-binding protein, MTL, in the test animals. These data suggest that the discovered MTL gene from S. domuncula is a sensitive indicator for environmental, bioavailable cadmium.

KEY WORDS: Cadmium · Sponges · Porifera · Suberites domuncula · Croatia · Metallothionein · Biomonitoring · Biomarker

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