| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 95 === White shrimp Lipopenaeus vannamei held in 35 ‰ seawater and pH 8.32 were examined the immune responses when the shrimp were subjected to salinity stress, pH stress, and injected with Vibrio alginolyticus.
White shrimp L. vannamei injected with tryptic soy broth (TSB)-grown V. alginolyticus (8 x 105 cfu shrimp-1), and then transferred to seawater at pH 6.46, 8.32 (control) and 10.21, respectively. After 12-172 h, mortality of V. alginolyticus-injected shrimp and placed in seawater at pH 6.47 and 10.21 was significantly higher than that of V. alginolyticus-injected and placed in seawater at pH 8.323. In another experiment, L. vannamei which had been reared at pH 8.32 were transferred to seawater at pH 6.47, 8.32 (co0ntrol) and 10.21 for 6, 12, 24, 72 and 120 h were examined for immune parameters, phagocytic activity and clearance efficiency of V. alginolyticus. The results indicated that the white shrimp which had been transferred to pH 6.47 and 10.21 after 12 h significantly decreased the THC, PO activity, respiratory burst, SOD activity, phagocytic activity and bacterial clearance efficiency as compared to the shrimp which reared at pH 8.32. These values returned to the normal after 120 h. It was therefore concluded that white shrimp L. vannamei which had been under low pH stress (6.47) or high pH stress (10.21) decreased the susceptibility of L. vannamei against V. alginolyticus infection by a depression in immune ability.
L. vannamei which had been reared at 35 ‰ seawater were transferred to 35 ‰ (control), 25 ‰ and 15 ‰, and examined for the immune parameters. The results indicated that the THC, PO activity, respiratory burst and SOD activity decreased significantly to 6 h, and indicated that the shrimp which had been challenged with V. alginolyticus, and then transferred to 25 and 15 decreased these immune parameters much more. The immune parameters returned to the normal after 120 of transfer. It was concluded that white L. vannamei subjected to salinity stress decreased its immune ability, and L. vannamei that had been infected with V. alginolyticus exacerbated the immune response when the shrimp were subjected to low salinity stress.
White shrimp L. vannamei which had been challenged with V. alginolyticus were examined the immune parameters. The results indicated that THC and PO activity significantly decreased after 12 h, whereas respiratory burst and SOD activity significantly decreased after 6 and 3 h, respectively. These immune parameters returned to the normal after 168 h. It was concluded that L. vannamei when infected with V. alginolyticus decreased its immune ability by decreasing the THC, PO activity, respiratory and SOD activity in 6-12, but these value returned to the normal after 168 h indicating immune modulation.
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