| This paper summarized activating mechanism of prophenoloxidase system of Litopenaeus vannamei acclimated to different salinity, discussed mainly the following theses:⑴Effect of dopamine injection on the prophenoloxidase system of the White Shrimp Litopenaeus vannamei.⑵Effect of dopamine on the defence parameters of white shrimp Litopenaeus vannamei.⑶Effect of salinity changes on the prophenoloxidase system of the White Shrimp Litopenaeus vannamei.⑷Effect of salinity changes on the defence parameters of the White Shrimp Litopenaeus vannamei.1,Effect of dopamine injection on the prophenoloxidase system of the White Shrimp Litopenaeus vannameiEffect of dopamine injection on the prophenoloxidase system of the White Shrimp Litopenaeus vannamei was studied. The haemocyte count, proPO activity, serine proteases activity, proteinase inhibitor activity andα2- microglobulin-like activity were measured after L. vannamei was injected individually with saline or dopamine at 10-7 mol/shrimp or 10-6mol/shrimp. Results showed that dopamine injection resulted in a significant effect on the parameters measured (p<0.05), while no significant difference in the parameters was observed in the control group (0.85% NaCl). During the experiment, all parameters in the experiment groups changed significantly. The haemocyte count reached the minima at 3h, granular and semi-granular cells became stable at 12h, and while hyaline cells and the total haemocyte count became stable at 18h. proPO activity reached the minima at 6h, then became stable at 9h. Serine proteases activity and proteinase inhibitor activity reached the minima at 3h, andα2- microglobulin-like activity reached its maximum at 3h, all the 3 parameters stabled at 12h. All parameters in experiment groups recovered to normal observed in the control group after they were stable.2,Effect of dopamine on the defence parameters of white shrimp Litopenaeus vannameiEffect of dopamine on the defence parameters of white shrimp Litopenaeus vannamei was studied. The results showed that dopamine injection resulted in a significant effect on haemocyte count, phenoloxidase activity, haemocyte phagocytic activity, bacteriolytic activity andα2- microglobulin-like activity in haemolymph of the White Shrimp L. vannamei(p<0.05), while no significant difference in the parameters was observed in the control group (0.85% NaCl). During the experiment, all parameters in the experiment groups changed significantly, different haemocyte count (DHC), total haemocyte count (THC) andα2- microglobulin-like activity reached the minima or maximum at 3h, phenoloxidase activity, haemocyte phagocytic activity and bacteriolytic activity reached the maximum or minima at 6h, and the change of these parameters had a negative or positive correlation with the dosage of dopamine injected. Granular cells, semi-granular cells, phenoloxidase activity andα2-microglobulin-like activity became stable after 12h, while hyaline cells, the total haemocyte counts and haemocyte phagocytic activity became stable after 18h, bacteriolytic activity stabled after 24h. All parameters in experiment groups recovered to normal observed in the control group after they were stable.3,Effect of salinity changes on the prophenoloxidase system of the White Shrimp Litopenaeus vannameiWater salinity changes (31→26, 21) were shown to have a significant effect on dopamine (DA) concentration, haemocyte count and the proPO system in the white shrimp Litopenaeus vannamei. No significant difference in any of the parameters was observed in the control group. DA concentration in haemolymph in the experimental groups increased to a peak value at 0.25d; Total haemocyte count (THC), differential haemocyte count (DHC), PO activity and proteinase inhibitor (PI) activity were lowest at 1d; serine proteases (SP) activity decreased to the lowest at 0.5d, whileα2-M activity increased to a peak value at 0.5d. DA concentration, haemocytes count and PO activity became stable after 1d, while other parameters stabilized after 3d. After these stabilized, there was no significant difference in all the parameters between the control and experimental groups except haemocytes count and PO activity.4,Effect of salinity changes on the defence parametes of the White Shrimp Litopenaeus vannameiThe immune response of white shrimp Litopenaeus vannamei to the change of salinity was studied. The results indicated that the change of salinity had a significant effect on the haemocyte count, percent phagocytsis, phenoloxidase activity, bacteriolytic activity andα2-microglobulin-like activity of Litopenaeus vannamei (P<0.05). Further, the change of these parameters had a positive correlation with the extent of salinity change. No significant difference in all parameters was observed in the control group during the experiment time. Total haemocyte count (THC) and different haemocyte count (DHC) reached the minima at 1d, stabilized afterwards and had a positive correlation with the salinity. The percent phagocytsis, phenoloxidase activity, bacteriolytic activity andα2-microglobulin-like activity in the experiment groups showed peak changes in the 3d and became stable afterwards. The percent phagocytsis and bacteriolytic activity were lowest at 0.5d, while phenoloxidase andα2-microglobulin-like activity reached the maximum at 0.5d and 1d respectively. All these four parameters had no significant difference with the control after stabilized. |
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