Phenoloxidases in ascidian hemocytes: characterization of the prophenoloxidaseactivating system

The phenoloxidase (PO) activity of the hemocytes lysate supernatant from three ascidians species, assayed by meansof 3-methyl-2-benzothiazolinone hydrazone hydrochloride, have been compared. PO-containing hemocytes were identifiedby a cytochemical reaction and the enzymatic activity measured by a spectrophotometric assay of lysate supernatantfrom hemocyte populations separated on a discontinuous Percoll density gradient. In Styela plicata, the enzyme appearedto be contained in morula cells only. In Ciona intestinalis, PO activity was shown in univacuolar refractile granulocyteand granular hemocyte. In Phallusia mammillata both compartment cell and granular hemocytes were positive. Enzymaticassay following electrophoretic analysis on polyacrylamide gel electrophoresis (PAGE) or SDS-PAGE indicated thathemocyte lysate presented orthodiphenoloxidase (catecholase) activity. The enzymes from the three species differed inmolecular size, activating substances and trypsin sensitivity. 2003 Elsevier Science Inc. All rights reserved.