Rapid increases in number of vanadocytes in the vanadium-rich ascidian, Ascidia sydneiensis samea, upon treatment of live animals with NH₄Cl

When the vanadium-rich ascidian Ascidia sydneiensis samea was immersed in seawater that contained 10 mM or 20 mM NH₄Cl for 20 hr, the number of blood cells increased dramatically. The specific type of blood cells whose level increased was identified as the signet ring cell, the so- called vanadocyte. Identification was made not only from morphological characteristics but also by immunological staining with a monoclonal antibody, S4D5, that is specific to signet ring cells. The initial number of signet ring cells was 2.30 x 10⁶ cells/ml of blood. The size of the subpopulation of signet ring cells increased about threefold during immersion in seawater plus 10 mM and 20 mM NH₄Cl, respectively, for 20 hr. No remarkable increases were observed in the populations of the other types of blood cells. However, concentration of vanadium in the blood rose slightly during the treatment with 10 mM or 20 mM NH₄Cl.