Hoeger, U., Dunn J. F. and Märker, C., Institut für Zoologie der Universität Mainz, Saarstr. 21, D - 6500 Mainz
| Eleocytes represent a specialized type of coelomic cells
in nereid annelids which assume a central role during germ cell development.
They may contain extremely high concentrations of both AMP and ADP (each
> 10 µMol/ml of cell vol.) whereas the ATP content is compara-tively
low (0.8 µMol/ml cell vol.). 31P-nuclear magnetic resonance studies
of living eleocytes suggest the compartmentalization of both AMP and ADP
in the large acidic vacuole characteristic for this cell type. Eleocytes
are thus capable of storing high concentrations of ADP and AMP without
inhibiting energy metabolism by sequestering these compounds in a separate
compartment. The high concentrations of both AMP and ADP in the eleocytes
decrease in both males and females during the course of maturation.
In eleocytes of male animals, the decline of the high nucleotide concentrations was accompanied by a transient increase of two intracellular nucleosides, inosine and guanosine. This suggests the degradation and further metabolism of nucleotides to the corresponding nucleo-sides. |
In culture, eleocytes release both inosine and guanosine into
the medium. Both nucleosides are also present in the coelomic fluid, the
common com-partment for both eleocytes and germ cells. Both male and female
germ cells incor-porate 14C-labelled inosine and guanosine in culture.
For oocytes, the further incor-poration of 14C-inosine into the RNA fraction
could be demonstrated. The large adenylate pools in the eleocytes may be
regarded as a store for purine compounds for later use by the growing germ
cells to supplement nucleic acid synthesis. The supply of nucleic acid
precursors seems to be another specific function of eleocytes related to
gametogenesis in addition to their known synthesis of vitellogenin. keywords: polychaete coelomic cells eleocytes adenylates ADP AMP inosine |
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