The Accumulation, retention and distribution of 95mTc in crab (Cancer pagurus L.) and lobster (Homarus gammarus L.). a comparative study

The accumulation, retention and distribution of 95mTc has been compared in lobsters and edible crabs kept under identical experimental conditions. The steady-state concentration factor (Css) for the uptake of 95mTc from seawater was significantly greater for female crabs (Css=17•9) than for males (Css=14•4), whereas in lobsters there was no such sex difference and the Css of 1161 was much greater than in crabs. The uptake of technetium from food (as indicated by whole body counts) was only moderately greater in lobsters than crabs. Retention of 95mTc was similar for crabs and lobsters of both sexes but the clearance rate was greater after the nuclide had been taken up from seawater (tb1/2=51 days) than from food (tb1/2=108 days). In all crabs and most male lobsters 95mTc was predominantly in the hepatopancreas while in a few male and all female lobsters it was mainly in muscle. Lobster ovaries consistently contained more activity than testes but this difference was not seen in crabs. In hepatopancreas cells of both species 95mTc occurred mainly in the cytosol and some initial steps were taken to determine the relationship between technetium and cytosol proteins. The results for crab and lobster are compared with those from previous studies on these and other crustacean species. The possible basis for the much higher concentrations of technetium in lobsters than crabs is discussed and further research suggested.