BIOSYNTHESIS OF HYDROXYEICOSATETRAENOIC ACIDS (HETES) IN MARINE AND FRESH-WATER HYDROIDS

1. Whole homogenates from six hydroid species, the marine Eudendrium rameum, Eudendrium racemosum, Sertularella sp., Halocordyle disticha and Aglaophenia pluma, and the freshwater Hydra oligactis were screened for their capability of synthesizing hydroxyeicosatetraenoic acids (HETEs) from exogenously added arachidonic acid (AA). 2. Only the homogenates from H. oligactis and H. disticha produced measurable amounts of a metabolite which was identified, by means of chromatographic and mass spectrometric techniques, as 11-HETE. 3. The possible formation of 11-hydroperoxyeicosatetraenoic acid (11-HPETE) in H. oligactis and of 9-HETE in A. pluma was also suggested on the basis of chromatographic evidence. 4. Both unbound and phospholipid-bound fatty acid composition was examined in these three species and compared, along with their HETE-synthesizing activity, with analogous data reported previously for the freshwater hydroid Hydra vulgaris.