ADENYLATE STORAGE, METABOLISM AND UTILIZATION IN CELOMIC CELLS OF THEPOLYCHAETE NEREIS-VIRENS (ANNELIDA, POLYCHAETA)

Eleocytes are specialized coelomic cells in nereid annelids which assu me a central role during germ cell development. They may contain extre mely high concentrations of both adenosine monophosphate (AMP) and ade nosine diphosphate (ADP) (each >10 mu mol/ml of cell vol.), whereas th e adenosine triphosphate (ATP) content is comparatively low (0.8 mu mo l/ml cell vol.). P-31 nuclear magnetic resonance (NMR) studies of livi ng eleocytes suggest the compartmentalization of both AMP and ADP in t he large acidic vacuole characteristic for this cell type. Eleocytes a re thus capable of storing high concentrations of ADP and AMP without inhibiting energy metabolism, by sequestering these compounds in a sep arate compartment. The high concentrations of both AMP and ADP in the eleocytes decrease in both males and females during the course of matu ration. In eleocytes of male animals, the decline of the high nucleoti de concentrations was accompanied by a transient increase of two intra cellular nucleosides, inosine and guanosine. This suggests the degrada tion and further metabolism of nucleotides to the corresponding nucleo sides. In culture, eleocytes release both inosine and guanosine into t he medium. Both nucleosides are also present in the coelomic fluid, th e common compartment for both eleocytes and germ cells. Both male and female germ cells incorporate C-14-labelled inosine and guanosine in c ulture. For oocytes, the further incorporation of [C-14]inosine into t he RNA fraction could be demonstrated. The large adenylate pools in th e eleocytes may be regarded as a store for purine compounds for later use by the growing germ cells to supplement nucleic acid synthesis. Th e supply of nucleic acid precursors seems to be another specific funct ion of eleocytes related to gametogenesis, in addition to their known synthesis of vitellogenin.