VALENCY OF VANADIUM IN THE VANADOCYTES OF ASCIDIA-GEMMATA SEPARATED BY DENSITY-GRADIENT CENTRIFUGATION

The amounts of total vanadium and vanadyl (+4) species contained in each blood cell type of ascidians were determined under a nitrogen atmosphere, using a combined approach of cell fractionation and vanadium measurement by ESR spectrometry. The vanadium-containing blood cells, the so-called vanadocytes, were the signet ring cells in Ascidia gemmata as well as A. ahodori and A. sydneiensis samea. Among several types of blood cell, only the vanadocyte contained vanadium in both +3 and +4 oxidation states, with a ratio of 97.6:2.4. The oxidation state of vanadium in the vanadocyte remained constant during the process of cell separation. Further, the oxidation state did not change in the presence of air, provided the cell did not suffer damage.