ISOLATION OF HIGHLY ACIDIC AND VANADIUM-CONTAINING BLOOD-CELLS FROM AMONG SEVERAL TYPES OF BLOOD-CELL FROM ASCIDIIDAE SPECIES BY DENSITY-GRADIENT CENTRIFUGATION

The reported pH values of ascidian blood cells vary considerably. It is likely that one or two of several different types of blood cell must have a highly acidic solution within their vacuoles, in which vanadium ions would be present in a reduced state. Thus, one of the reasons for the variation in reported pH values may be that measurements of pH were made without fractionation of the total population of cells. In the present experiments, the combination of fractionation of whole cells by density-gradient centrifugation, use of a microelectrode that allows measurements of pH under anaerobic conditions, and atomic absorption spectrometry for determinations of vanadium revealed that the contents of signet ring cells, recently identified as vanadocytes, of three ascidian species, Ascidia gemmata, A. ahodori, and A. sydneiensis samea, had low pH values of 2.4, 2.7, and 4.2, respectively. Results obtained by ESR (electron spin resonance) spectrometry confirmed the values of pH obtained with the microelectrode.