A Comparative Study of the Uptake, Clearance and Metabolism of Technetium in Lobster (Homarus Gammarus) and Edible Crab (Cancer Paguras)

Lobsters and edible crabs have been exposed to 95Tcm in their sea water or in their food, and the uptake, retention and distribution of the isotope in their bodies examined. The steady-state concentration factor Css for uptake of 95Tcm from sea water was significantly greater for female crabs (Css=17.9) than for males (Css=14.4). There was no such sex difference in lobsters and they took up 95Tcm to much higher levels with a Css of 1160. Retention of the isotope was similar for crabs and lobsters and for animals of both sexes. However the route of uptake was important with more rapid clearance after uptake from sea water (tb1/2 = 51 days) than after uptake from food (tb1/2 = 108 days). Technetium was found predominantly in the hepatopancreas of all crabs and most male lobsters. In a few male lobsters and all females it was mainly in muscle. Lobster ovaries consistently contained more activity than testes but this difference was not seen in crabs. At the subcellular level 95Tcm in hepatopancreas cells of both lobster and crab occurred mainly in the cytosol. Results of initial studies into the relationships between technetium and cytosol proteins are given and the possible basis for the much greater accumulation of the element by lobsters than crabs discussed. (author)