高温、低盐对菲律宾蛤仔免疫能力的影响

Synergistic effects of high temperature and low salinity on immunity of Manila clam Ruditapes philippinarum

为查明温度(21、30℃)和盐度(7、15、32)互作对菲律宾蛤仔Ruditapes philippinarum免疫能力的影响,对不同温度和盐度条件下试验0、3、6、12、24、48、72 h时,体质量为(14.8±0.731)g蛤仔的血细胞数、血淋巴吞噬能力和渗透压,以及血清中溶菌酶(LZM)、碱性磷酸酶(AKP)活性的变化进行了研究。结果表明:以各指标0 h水平为对照,常温常盐组(21℃,32)蛤仔各指标在0~72 h内虽有波动,但变化并不显著(P>0.05);各试验组蛤仔血细胞数有不同的变化趋势,72 h时,常温低盐组(21℃,7)蛤仔恢复初始水平,而常温中盐组(21℃,15)、高温中盐组(30℃,15)和高温常盐组(30℃,32)蛤仔血细胞数最终仍未恢复,高温低盐组(30℃,7)蛤仔虽在24 h时恢复初始水平,但在48 h时全部死亡;高温常盐组蛤仔吞噬能力先升高后降低在72 h时仍低于初始水平(P<0.05),2个中盐组和常温低盐组蛤仔吞噬活性最终恢复,而高温低盐组蛤仔吞噬活性在24 h时仍处于较高水平(P<0.05);各试验组蛤仔LZM活性在72 h时均显著高于初始水平(P<0.05);常温中盐组蛤仔AKP活性在3 h出现最大值,最终所有试验组AKP在72 h时恢复初始水平;2个中盐组和2个低盐组蛤仔渗透压均逐渐降低,而高温常盐组蛤仔渗透压逐渐升高,在72 h时均未恢复初始水平。研究表明,温度升高的同时降低盐度,将会对贝类免疫能力造成严重的影响,这可能是夏季滩涂贝类死亡率较高的一个重要原因。

The changes in blood cell count, phagocytosis ability, osmotic pressure, and activities of lysozyme （LZM） , and alkaline phosphatase （ AKP） in serum were monitored in Manila clam Ruditapes philippinarum with body weight of （14.8±0.73）g exposed to temperatures（21 ℃,and 30 ℃）and a salinity of 7, 15, and 32 for 0, 3,6, 12,24,48 ,and 72 h in order to investigate the synergistic effects of temperatures and salinity on the immuni-ty of Manila clam. The results showed that there were some fluctuations in blood parameters and activities of serum LZM and AKP in the experimental groups at water temperature of 21 ℃ and a salinity of 32, without significant differences （P 〉0.05） in 0-72 h compared with initial level in the control group. The blood cells counts were re-covered to the initial level in the clam in the 21 ℃ and low salinity of 7 group in 72 h , while the blood cells counts were not returned to the initial level in the clam in the 30 ℃,32 ℃ and salinity 32 groups in 72 h. The clam in high temperature 30 ℃ and low salinity 7 group died in 48 h , although they had recovery blood cell count in 24 h. The clam in high temperature 30 ℃ and low salinity 7 showed elevated phagocytosis first and then decrease in hago- cytosisd, even lower than the initial level in 72 h（ P〈0. 05） , while the clam in medium salinity 15 and 7 and 21 ℃ groups had recovery phagocytic activities, with higher phagocytosis in high temperature 30 ℃ and low salinity 7 groups in 24 h （ P〈0. 05）. There were significantly higher LZM activities than the initial level in the clam among experimental groups in 72 h （ P〈0. 05） , with the maximal AKP activity in 3 h and recovery initial levels in 72 h.The gradual decrease in osmotic pressure was observed in medium and low salinity groups, while the gradual in-crease in osmotic pressure in the high temperature 30 ℃ and salinity 32 group, without recovery initial level in 72 h. The findings indicate that the interaction of temperatures increase and salinity decrease will have a more seriouseffect on the immunity of shellfish, which may be involved in the high mortality of mudflat shellfish in summer.