Uptake and Excretion of Cobalt by Sea Cucumber Stichopus japonicus and Prawn Penaeus japonicus

Abstract

Radiocobalt tracer experiments were carried out to obtain further information on the biochemical behavior of this nuclide in sea cucumber and prawn. The biological half lives of ⁶⁰Co (inorganic cobalt in sea water) were calculated at 73 days for sea cucumber and 24 days for prawn. The ⁶⁰Co-binding constituents in the organs and tissues of these organisms were extracted with a Tris-acetate buffer solution and separated using gel filtration on Sephadex G-75. Although most radioactivity (86%) in the crude extraction of sea cucumber (without intestine)was found in a relatively high molecular weight fraction (more than 80000), that in prawn liver was observed in a low molecular weight fraction (less than 5000). From analysis for carbohydrates, a large portion of carbohydrates in the prawn liver was found in the high molecular fraction, however, the presence was observed in the low molecular weight fraction, too. Further characterization by electrophoresis showed that this fraction contained at least four ⁶⁰Co-binding proteins or peptides and significant quantities of ⁶⁰Co-binding carbohydrates.
The biological role and detailed chemical nature of the components await further study.