THE DISTRIBUTION AND TAXONOMIC VALUE OF FATTY-ACIDS AND EICOSANOIDS IN THE LIPOMYCETACEAE AND DIPODASCACEAE

Using radioimmunoassay, blood platelet aggregation studies and GC-MS the existence of prostaglandins in the endomycetalean yeast Dipodascopsis uninucleata was confirmed by our group. These findings triggered the search for similar eicosanoids in the rest of the Endomycetales. We commenced by scanning for the easily detectable precursors of eicosanoids, linoleic- and linolenic acid. We selected two families (i.e. Lipomycetaceae and Dipodascaceae), both producing these precursors, for further investigation. Representative strains of the two families were tested for their ability to grow in the presence of 1 mM aspirin, a specific inhibitor of prostaglandin biosynthesis. In contrast to the lipomycetaceous species the dipodascaceous species were insensitive to this drug. These results were verified when representative strains of both families were investigated for their ability to produce eicosanoids from externally fed radio-labeled arachidonic acid along an aspirin sensitive pathway. Thin layer chromatography of culture extracts, followed by autoradiography, showed that while none of the Dipodascaceae produced aspirin sensitive arachidonic acid metabolites, the members of the Lipomycetaceae tested positive for these metabolites. These findings supported the separation of the lipomycetaceous yeast Dipodascopsis from the Dipodascaceae. The findings also correlate with the delimitation of these yeasts in two families (i.e. Dipodascaceae and Lipomycetaceae). Further investigation indicated that prostaglandin production by the genus Dipodascopsis is mainly associated with ascosporogenesis. Thin layer chromatography of cell extracts from Dipodascopsis tothii, followed by scintillation counting, indicated the presence of PGF2alpha and PGE2 during ascosporogenesis.