This study is an investigation into the non-specific immune systems of bony and cartilaginous fish. Rainbow trout (<i>Oncorhynchus mykiss)</i> head kidney macrophages were incubated with zymosan particles (opsonized in normal trout serum) and the extent of phagocytosis was compared with that of non-opsonised particles. Long-term exposure of these macrophages to purified complement factor C3a-1 resulted in the enhanced generation of prostaglandin E<sub>2</sub> (PGE<sub>2</sub>) that was confirmed using gas chromatography-electron capture mass spectrometry and quantified using enzyme immunoassay. In initial studies, the enhanced generation of PGE<sub>2</sub> was found to be due to the upregulation of cyclooxygenase-2 using RNA extraction and reverse transcription-polymerase chain reaction analysis. Histological sections of muscle, oesophagus, spleen gonad, liver, intestine and gill from the Thornback ray, <i>Raja clavata</i> were examined and areas of haemopoiesis highlighted. The principal sites of haemopoiesis were in the gonads and oesphagus. All tissues were found to generate PGE and several lipoxygenase products. Five of these products were identified as 6-<i>trans-</i>leukotriene (LT)B<sub>4</sub>, 6-<i>trans</i>-12-epi-LTB<sub>4</sub>, 8-15 dihydroxyeicosttetraenoic acid (HETE), 15-HETE and 15-hydroxyeicosapentaenoic acid (HEPE). No LTB<sub>4</sub> generation was observed. Incubation of oesophageal leucocytes with authentic LTA<sub>4</sub> did not result in the generation of LTB<sub>4</sub>, suggesting the absence of LTA<sub>4</sub> hydrolase. Initial studies of the natural humoral antibacterial activity of serum from rays <i>(R. clavata)</i>, dogfish (<i>Scyliorhinus canicula)</i> and trout, and of dogfish leucocytes and trout thrombocytes were carried out using a microtitre plate based killing assay against several species of bacteria. Variable levels of antibacterial activity were found in these samples although the reproducibility of this method was questioned. Lysozyme-like activity in serum from rays and dogfish, and in the leucocytes of dogfish and thrombocytes of trout was also quantified. In particular the thrombocytes were found to contain lysozyme-like activity in significant amounts suggesting a role for these cells in antibacterial defence.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:638242 |
| Date | January 2003 |
| Creators | Morgan, E. L. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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