Intracellular acidity in the ascidian

Abstract

1. 1. Morula cells of three Ascidiidae and two Perophoridae from the suborder Phlebobranchia, and one Holozoidae and one Clavelinidae from the suborder Aplousobranchia were acidic to neutral red; where methyl red was used, the stain corresponded to pH values between 4.6 and 6.0 depending on species. Five Didemnids (Aplousobranchia), and two Pyuridae, two Styelidae, and one Molgulidae (Stolidobranchia) had neutral morula cells. All compartment cells were neutral. 2. 2. Phosphorus-31 NMR spectrum of blood cells of Pyura stolonifera (Stolidobranchia) had P i signals corresponding to pH 6.4 and 6.1, probably from phosphate within the globules and cytoplasm of the morula cells. The 31P NMR spectra of whole colonies of Diplosoma similis and Diplosoma virens had signals corresponding to P i at pH values of 5.58 and 5.65. 3. 3. In Phlebobranchia, acid released by vanadocytes upon lysis could not be accounted for solely by the hydrolysis of V(III) and Fe(III), but within the vanadocytes the pH is too high for the metals to be in hydrated forms. 4. 4. Tunic acid was examined. The tunic cells of many species of Aplousobranchia and Phlebobranchia released acid on lysis but the intact cells were neutral.