Establishment of a primary cell culture from a sponge: primmorphs from Suberites domuncula

In spite of the fact that cells from the phylum Porifera (sponges) contain high levels of telomerase activity. no successful approach to cultivate spo nge cells has yet been described. Telomerase is the enzyme which catalyzes the addition of new telomeres onto chromosome ends which have been lost aft er each round of DNA synthesis. One reason may be seen in the observation t hat after dissociation the cells lose their telomerase activity. In additio n, no nutrients and metabolites have been identified that would stimulate s ponge cells to divide. We report here the culture conditions required for t he formation of multicellular aggregates from Suberites domuncula from diss ociated single cells; they are termed primmorphs. These aggregates, formed in seawater supplemented with antibiotics, have a tissue-like appearance; t hey have been cultured for more than 5 mo. Cross sections through the primm orphs revealed an organized zonation into a distinct unicellular epithelium -like layer of pinacocytes and a central zone composed primarily of spherul ous cells. After their association into primmorphs, the cells turn from the telomerase-negative state to the telomerase-positive state. Important is t he finding that a major fraction of the cells in the primmorphs undergo DNA synthesis and hence have the capacity to divide. By applying the BrdU (5-b romo-2'-deoxy-uridine)-labeling and detection assay it is demonstrated that up to 33.8 % of the cells in the primmorphs are labeled with BrdU after an incubation period of 12 h. It is proposed that the primmorph system descri bed here is a powerful never model system to study basic mechanisms of cell proliferation and cell death; it can also be used in aquaculture, for the production of bioactive compounds and as a bioindicator system.