维氏气单胞菌感染对西伯利亚鲟血清指标和hsp70基因表达的影响

Changes in serum index and hsp70 gene expression in Siberian sturgeon Acipenser baerii challenged with Aeromonas veronii

为研究西伯利亚鲟Acipenser baerii在维氏气单胞菌Aeromonas veronii感染过程中的生理免疫反应,进行了维氏气单胞菌攻毒试验,将体质量为(260.2±37.8)g的西伯利亚鲟从背部肌肉注射菌液浓度为2.0×107cfu/mL的维氏气单胞菌,注射后40h后开始死亡,62h后停止死亡,累积死亡率为46.7%。结果表明:40h对照组和53h处理正常鱼组中的血清皮质醇含量最低,与不再出现死亡后的处理组和对照组无显著性差异(P>0.05),与处理患病鱼各组有显著性差异(P<0.05);62h处理组血清超氧化物歧化酶(SOD)活力最低,与40h对照组、53h处理组、53h处理正常鱼组、93h对照组、93h处理组有显著性差异(P<0.05);93h处理组血清丙二醛(MDA)含量最低,与40h处理组、44h处理组、53h处理正常鱼组、62h处理组有显著性差异(P<0.05),其他各组之间无显著性差异(P>0.05);各处理组血清溶菌酶(LZM)活力从44h开始升高,直到62h,各个处理组均显著高于40h的处理组和对照组以及93h和168h的对照组和处理组(P<0.05);实时定量了肝、鳃、脾、肠组织中hsp70基因表达的变化。研究表明:西伯利亚鲟感染维氏气单胞菌后,血清皮质醇含量和溶菌酶活力升高可作为机体免疫状态的参考指标;热休克蛋白hsp70基因的诱导表达较血清指标变化更为灵敏,hsp70基因在鳃组织最先有较高的诱导表达。

Siberian sturgeon Acipenser baerii with body weight of （260.2±37.8）g were injected with Aeromonas veronii in dorsal muscles and serum indices including activities of lysozyme （LZM）, superoxide dismutase （SOD） and contents of cortisol, and malondialdehyde （MDA） and hsp70 gene expression were studied in liver, spleen, intestine and gill by quantitative PCR to evaluate the immune physiological response of Siberian sturgeon infected by the bacteria. The initial mortality was observed in the fish 40 h after muscular injection, no death was found 62 h after muscular injection, with cumulative mortality of 46.7%. The minimal serum cortisol content was observed in the fish in the control group in 40 h exposure and in the treatment groups in 53 h exposure without compared with the samples collected in the no death period （ P〉0.05 ） and significant difference from the diseased fish in the treatment groups （P〈0.05）. The minimal SOD activity was found in the fish in the treatment groups in 62 h expo- sure and significant difference from the fish in the control group in 40 h and 93 h exposure, in the treatment groups in 53 h, 62 h and 93 h exposure and in the normal fish in the treatment groups in 53 h exposure （P〈0.05）. There was significant difference in MDA level in the treatment in 93 h exposure from those in the treatment groups in 40 h, 44 h, 53 h, and 62 exposure （ P〈0.05 ）, without significant difference among the other groups （ P〉0.05 ）. The lysozyme activity was found to be increased in the treatment groups in 44 h exposure, significantly higher in 62 h exposure than those in the treatment groups in 40 h, 93 h, and 168 h exposure and in the control group in 40 h, 93 h, and 168 h exposure （P〈0.05）. The findings indicate that the expression of hsp70 gene in tissues is more re- sponsive than serum cortisol level and lysozyme activity which act as the reference indices of the immune status at high values, and that the higher hsp70 gene expression was first found in gills.