Abstract
Iron accumulation by the tunicate Styela clava was investigated. Live specimens did not show uptake of dissolved iron from sea water, although their tunics showed a high affinity for iron adsorption. In partitioning experiments, the tunic of S. clava was shown to be impermeable to dissolved iron. The most likely source of iron is particulate matter that tunicates filter through their siphons from sea water. Iron uptake by S. clava blood cells was studied. Iron(II) uptake by the cells was shown to be biphasic. Uptake was shown to be an irreversible process for the time span studied. The metabolic inhibitor 2-deoxyglucose did not inhibit uptake. Citrate blocked uptake. Addition of Ga(III) did not affect uptake, implying that iron(II) does not undergo oxidation changes during accumulation by the blood cells. Uptake did not occur through anionic channels. Iron(III) uptake studies were inconclusive because of the low solubility of uncomplexed iron(III) species.