Cadmium is deposited in the gut content of larvae of the beetle Tenebrio molitor and involves a Cd-binding protein of the low cysteine type.
Binding of cadmium (Cd) to metallothionein (MT) and non-MT proteins with low contents of cysteine has been observed in terrestrial arthropods. We recently isolated a Cd-binding protein with no cysteine that was induced in Cd-exposed larvae of the beetle Tenebrio molitor. In this study we have examined the molecular distribution of Cd within extracts of different tissues and compartments of Cd-exposed T. molitor larvae. A Cd-peak consistent with the low cysteine Cd-binding protein was induced within the gut content where it could be detected after 4-8 days of exposure. Examination of gut wall tissue revealed no increase in Cd-binding capacity, indicating that no accumulation of MTs was taking place in this tissue. Incorporation of Cd in the gut wall tissue stabilized after 8 days of Cd-exposure at a rather low level compared to the other organs. There was a statistical trend towards Cd being incorporated in the gut content in a manner that was disproportionally high compared to the amount of Cd in the gut wall tissue. The possible role of the low cysteine Cd-binding protein in reducing the uptake of Cd in the tissues is discussed.
Pedersen
S A
SA
Laboratory of Ecophysiology and Toxicology, Institute of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway. sindre.pedersen@bio.ntnu.no
Kristiansen
E
E
Andersen
R A
RA
Zachariassen
K E
KE
D000818:Animals; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D002850:Chromatography, Gel; D005766:Gastrointestinal Contents / Q000737:chemistry*; D007413:Intestinal Mucosa / Q000378:metabolism; D007814:Larva / Q000378:metabolism; D008668:Metallothionein / Q000302:isolation & purification / Q000378:metabolism*; D013712:Tenebrio / Q000378:metabolism*
C004203:cadmium-binding protein; D002104:Cadmium; D008668:Metallothionein