The predominant eicosanoids generated by <i>Balanus perforatus</i> were examined on a monthly basis by reverse phase high pressure liquid chromatography and were identified as 8-hydroxyeicosapentaenoic acid, and 8-hydroxyeicosatetraenoic acid, with their generation correlating with the environmental seawater temperature. No change in either apparent lipoxygenase activity or precursor fatty acid levels were found with the time of year. Changes in fatty acid composition followed the trend expected by homeoviscous adaptation. The subtidal barnacle <i>B. balanus</i> was found to generate an unusual range of products which were tissue-specific in generation, with the testes/seminal vesicles producing large amounts of a novel eicosanoid identified by mass spectrometry as 8,13-dihydroxyeicosapentaenoic acid (diHEPE). This product was highly acid-labile, degrading to a range of unidentified conjugated triene- and pentaene-containing products. Addition of 8,13-diHEPE to excised barnacles increased muscular contractions which is believed to aid in fertilisation. Preliminary results suggest biosynthesis through joint lipoxygenase and cytochrome P450 pathways. The involvement of various eicosanoids, particularly trioxilins and hepoxilins in triggering egg-hatching of <i>Elminius modestus</i> larvae was examined. In contrast to previous reports, trioxilin A<sub>3</sub> was not found to cause egg-hatching, whereas its unstable epoxide precursor, hepoxilin A<sub>3</sub>, and the synthetic hepoxilin analogue, PBT-3, did at concentrations of 10<sup>-6 </sup>and 10<sup>-7</sup> M respectively. Crude barnacle extracts are known to cause an increase in the settlement of <i>B. amphitrite</i>, although in this study crude adult extracts separated by chromatography had no significant effect on levels of settlement, although the precursor fatty acid arachidonic acid caused an increase in settlement. A range of plant-derived terpenoids were found to inhibit settlement of <i>B. amphitrite.</i>
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:638022 |
| Date | January 2005 |
| Creators | Maskrey, B. H. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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