Cadmium In Crabs Research Articles

Tracing simultaneous cadmium accumulation from different uptake routes in brown crab Cancer pagurus by the use of stable isotopes

High concentrations of cadmium in brown crab are an issue of food safety, and large variations between different areas have been found. To investigate the relative importance of dietary and aqueous uptake regarding the overall accumulation in brown crab, we used stable isotopes to trace the uptake from both routes simultaneously in the same animals. We demonstrated that the analytical challenges regarding background concentrations of natural isotope distribution and polyatomic interferences in the different matrices can be overcome with an appropriate analytical setup and modern mathematical corrections using a computer software. Cadmium was accumulated via both routes and was found in all measured organs at the end of the exposure phase. The obtained data were used to establish accumulation curves for both uptake routes and estimate accumulation parameters for hepatopancreas, as the most important organ in crab regarding total cadmium body burden. Using the estimated parameters in combination with naturally relevant cadmium concentrations in seawater and diet in a model, allowed us to predict the relative importance of the aqueous and dietary uptake route to the total hepatopancreas burden. According to the prediction, the dietary route is the main route of uptake in brown crab with a minimum of 98% of the accumulated cadmium in hepatopancreas originating from diet. Future studies addressing the source and accumulation of cadmium in crab should therefore focus on the uptake from feed and factors connected to foraging.

DETERMINATION OF CADMIUM IN EDIBLE TISSUES OF CRABS CATCH IN ITALIAN TERITORIAL WATERS: MONITORING ON EMILIA ROMAGNA REGION

On 2008 there was a Community alert concerning the presence of Cadmium in crabs and on December 2009 there was a note from the Italian Ministry of Health concerning the control of cadmium in edible tissues of crabs caught in Italian territorial waters. This laboratory analyzed a total of 32 samples of crabs by atomic absorption spectroscopy graphite stove dividing the crustaceans in the following tissues: bright parts contained in claws, dark parts contained in the shell and red parts contained in the shell. The results showed that gastrointestinal shellfish tissues is at greatest risk, while the bright parts contained in claws are always below the limit set by European legislation (Reg. 1881/2006 and following). Furthermore it is clear that the crustaceans caught in the northern Adriatic present values of cadmium significantly lower compared to shellfish from France and UK.

Occurrence of Cadmium in Crabs (Cancer pagurus) and the Isolation and Properties of Cadmium Metallothionein

Occurrence of Cadmium in Crabs (Cancer pagurus) and the Isolation and Properties of Cadmium Metallothionein

Occurrence of cadmium in crabs (Cancer pagurus) and the isolation and properties of cadmium metallothionein.

The occurrence of high cadmium levels in the digestive gland (hepatopancreas) of the crab Cancer pagurus is reviewed and its possible significance to human health is discussed. Previous attempts to isolate this cadmium in its native form are briefly reviewed and the present method used in this laboratory to isolate crab cadmium metallothionein is described. Quantitative amino acid analysis of the purified protein suggests that it has a total of 55 residues, including 19 Cys, and a molecular weight of approximately 5800. This yields an extinction coefficient at 220 nm for the protein in HCl, pH 1.5, of 50,000 and at 250 nm for the native cadmium protein in Tris-HCl, pH 8.4, of 92,000.

Evidence for the natural occurance of (cadmium, copper)-metallothionein in the crab Cancer pagurus

1. The presence of high cadmium in crabs, Cancer pagurus, from Orkney and Shetland has been confirmed. The mean value for cadmium in these crabs is about 3 times higher than those from Devon and Aberdeen, but the peak values are about 5 times higher. 2. A low molecular weight, heat-stable, cadmium and copper binding protein having the characteristics of metallothionein has been isolated from the hepatopancreas of wild specimens of the crab, Cancer pagurus. 3. Induction of metallothionein was achieved both by feeding with cadmium treated mussels and by injection. 4. The major product isolated showed a pair of bands on gel electrophoresis. They were designated metallothionein II-A and II-B and had apparent molecular weights of approx 10,000–11,000. The cysteine content was 30 mol% and the molar ratios of cadmium, copper and zinc were 49:49:2. The sulphydryl to cadmium ratio was 3.