Hitoshi Michibata

Zoological Science, 13(4), 489-502, (1 August 1996) doi:10.2108/zsj.13.489

The Mechanism of Accumulation of Vanadium by Ascidians: Some Progress towards an Understanding of this Unusual Phenomenon

Vanadium detected by neutron activation that causes γ-ray emission at 1,434 keV. Blood cells of Ascidia gemmata contained ~350 mM ov vanadium. Other Phlebobranchia contained 20–60 mM, but C. intestinalis contained only 0.6. Stolidobranchia contained much lower amounts. Vanadium-containing cells (vanadocytes) were identified as signet cells. Sulfonic acid might be the counter ion. Vanadocyte pH is very low (1.9–4.2). There exist other low-pH cells that do not contain vanadium. Accumulation of vanadium may involve a mechanism using a vacuolar-type H+-ATPase. Vanadium contents of the embryo are low but increase during embryogenesis.