碩士 / 國立屏東科技大學 / 熱帶農業研究所 / 89 / Dissolved oxygen (DO) affects the physiological and immunological responses of the giant freshwater prawn, Macrobrachium rosenbergii (de Man), resulting in the reduction in the physiology, cellular immunity, and disease resistance ability of its hemolymph. After the prawn was exposed to DO at 1.75, 2.75, 4.75 and 7.75 mg/l (normoxia), the hemolymph osmolality, ionic, oxyhemocynin, protein, pH, PCO2 and PO2 were measured at 0, 6, 12, 24, 48, 96 and 144 h. After the prawn being expoused to DO at 1.75 mg/l, its hemolymph osmolality, Cl-, Na+ and K+ decreased significantly at 12, 12, 12, and 6 h, respectively. However, its hemolymph pH, PCO2, HCO3-, TCO2, oxyhemocyanin and protein increased significantly at 6, 6, 6, 6, 48, and 24 h, respectively, but stabilized to normal after 24 h. When the prawn was exposed to DO at 4.75 mg/l, only hemplymph osmolality and Cl- decreased significantly at 48 and 24 h, respectively. Results of the study showed that under the hypoxia at 2.75 and 1.75 mg/l for a relatively short period of 12 h, the hemolymph osmolality, ion, oxyhaemocyanin, total protein, respiratory gas and acid-base balance regulation were negatively affected. However, when the exposure was longer than 48 h, the prawn appeared to demonstrate a phenomenon of physiology adaptation.
After the prawn (14-19 g) was challenged with Lactococcus garvieae, which had been previously incubated in TSB medium for 24 h, and then the prawn was placed in water with different concentrations of DO at 7.75, 4.75, 2.75 and 1.75 mg/l. Mortality was observed 6 h after the prawn being exposed to low DO at 1.75 mg/l and 12 h after being exposed to a higher DO at 2.75 mg/l. The mortality of the prawn when exposed to DO at 1.75 mg/l was significantly higher than that at 4.75 and 2.75 mg/l. The mortality of the prawn, when exposed to DO at 4.75 and 2.75 mg/l, was significantly higher than that at 7.75 mg/l after 48 h. The THC (total hemocyte counts), DHC (differential hemocyte counts), phenoloxidase activity, respiratory burst in NBT reduction, phagocytoic activity and clearance efficiency of the prawn (20—30 g) were determined after it had been exposed for 120 h to DO at 7.75, 4.75, 2.75 and 1.75 mg/l. No significant difference in semi-granular cells and granular cells of the prawn was observed among the four treatments. The THC and hyaline cells of the prawn, after it had been exposed for 120 h to DO at 2.75 mg/l, decreased significantly by 36 % and 39 %, respectively. The phenoloxidase activity and respiratory burst in NBT decreased significantly by 33 % and 11 %, respectively, after the prawn was exposed to DO at 2.75 mg/l for 24 h and 72 h, respectively. The phagocytosis activity and clearance efficiency decreased significantly by 44 % and 54 %, respectively, after the prawn was exposed to DO at 2.75 mg/l for 12 h. It is concluded that when the prawn was exposed to DO lower than 2.75 mg/l, the immune system of the prawn was impaired and its immunity decreased, resulting in the increase in the susceptibility of the prawn to L. garvieae.
| Identifer | oai:union.ndltd.org:TW/089NPUST643016 |
| Date | January 2001 |
| Creators | Chun-Hung Liu, 劉俊宏 |
| Contributors | Winton Cheng, 鄭文騰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 130 |
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