碩士 / 國立臺灣海洋大學 / 水產養殖學系 / 93 / Abstract
This thesis investigated the pathogenesis of Photobacterium damselae subsp. piscicida in cultured cobia ( Rachycentron canadum ). Strain 9205 originally isobated from livers , spleen , kidney and ascites moribum cobia ( 3-30 g ) was used in the study. The bacterial cell and extracellular products ( ECP ) were lethal to the cobia ( 5 g ) with LD50 values of 3.28 x 104 CFU and 3.25µg protein / g fish ,respectively. Extracellular phospholipase were partially purified by using various columns ( Q Sepharose HP and RESOURCE Q ) on HPLC system. Two protein bands ( 27 and 58Kda ) exhibited phospholipase actiuities on Native – PAGE but on SDS-PAGE ( by 0.3% egg yolk agar-overlay ) ware excised and eluted as the final purification step. The 27KDa and 58KDa factions were determined and identified as Phospholipase C ( PLC ) and Phospholipase A2 ( PLA2 ), respectively , by using PLC Assay Kit and PLA2 Assay Kit﹒Both of the two phospholipase were hemolytic against red blood cells of cobia. The LD50 values of PLC ( 27Kda ) and PLA2 ( 58Kda ) were 0.91 µg protein (lower than ECP ) and 7.06 µg protein / g fish ( higher than ECP ) in cobia, respectively. In addition, the LD50 value of 33Kda protease was 6.8 µg protein / g fish in cobia. The combination of LPS with PLC, PLA2 or protease did not evhance the lethal toxicity remarkably. Furthermore, the PLC ( 27KDa ) was confirmed to be a major extracellular toxin by a toxicity – neutraligation test. The PLC and PLA2 and protease were immunoreactive against cobia sera pre-immunized with formalinized ECP. The result indicates that three toxins are immunogenic in cobia and may by very useful for future vaccine development.
| Identifer | oai:union.ndltd.org:TW/093NTOU5086044 |
| Date | January 2005 |
| Creators | Zhi-Quan Hu, 胡志全 |
| Contributors | Ping-Chung Liu, 劉秉忠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 110 |
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