CHEMISTRY OF THE BLOOD OF THE ASCIDIANPODOCLAVELLA MOLUCCENSIS

Abstract

The blood plasma of the aplousobranch Podoclavella moluccensis was found to have features similar to the plasma of ascidians from different suborders, including the presence of a yellow saccharide. The plasma concentrates a number of transition metals, especially vanadium, manganese, zinc, and chromium. The dominant blood cells were yellow morula cells and blue granular cells. A yellow ethanolic extract of the cells had a visible spectrum similar to a β-carotene with an additional intense absorption at about 270 nm. Magnesium and a trace of iron (III) were the only metals detected in that fraction. A subsequent purple acidified-ethanol extract, also possibly a carotenoid, and the cell residue contained a number of metals. Relative to the plasma, these two fractions concentrated calcium, and also iron, vanadium, and chromium, to a much greater extent than magnesium. This is the first report of chromium in the blood cells of ascidians or of significant concentrations of zinc in the plasma. The vanadium was not present as V (III) in the morula cells, as it is in some phlebobranchs, but appears to be in the granular cells, and the cell residue gave an ESR signal characteristic of VO2+. The UV-visible and circular dichroism spectra of the various blood fractions are reported and compared to similar fractions from the aplousobranch Sigillina cyanea and the stolidobranch Polycarpa pedunculata.