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以凡纳滨对虾(Litopenaeus vannamei)为研究对象,探讨饲料中添加聚β-羟基丁酸酯(Poly-β-hydroxybutyrate,PHB)对其非特异性免疫能力的影响。采用单因子浓度梯度法,在基础饲料中分别添加1.0%、2.5%和5.0%的PHB配制成实验饲料,饲喂21 d后测定对虾免疫酶活性,选择最佳浓度组与空白对照组进行氨氮胁迫实验,测定对虾丙二醛(MDA)含量,同时利用RT-PCR技术测定氨氮胁迫48 h内对虾免疫基因表达水平,观察PHB对免疫基因表达量的影响。结果显示,总抗氧化能力(T-AOC)随PHB浓度升高呈现先上升后下降的趋势,血液、肝胰腺及鳃丝中T-AOC分别在2.5%、2.5%及1.0%PHB浓度时达到最高;PHB对肝胰腺中超氧化物歧化酶(SOD)活力无显著影响,血淋巴及鳃丝中SOD活力在最高浓度组(5.0%PHB)与对照组之间差异显著(P<0.05);过氧化物酶(POD)和溶菌酶(LZM)在鳃和肝胰腺中的活力于PHB浓度为1.0%和2.5%时达到最高,其中POD相对于对照组分别提高了7.63倍和0.68倍,LZM活力分别提高了0.88及0.18倍。氨氮胁迫实验结果显示,对虾经PHB饲喂后,体内免疫基因表达量高于对照组,且体内MDA含量低于对照组。综上结果说明,PHB能提高凡纳滨对虾非特异性免疫能力。
Litopenaeus vannamei was used to investigate the effect of poly-β-hydroxybutyrate (PHB) on its non-specific immunity. One-factor concentration gradient method was used to prepare experimental feedstuff by adding 1.0%, 2.5% and 5.0% PHB into the basic feed respectively. After 21 days of feeding, the immunoenzyme activity of shrimp was determined. The best concentration group and the blank control group were selected for ammonia nitrogen Stress test was conducted to determine the content of malondialdehyde (MDA) in shrimp. Meanwhile, the expression level of immune genes in shrimp was determined by RT-PCR and the effect of PHB on the expression of immune genes was observed. The results showed that the total antioxidant capacity (T-AOC) increased first and then decreased with increasing PHB concentration. The T-AOC in blood, hepatopancreas and gill filaments reached 2.5%, 2.5% and 1.0% PHB respectively (P <0.05). The activity of superoxide dismutase (SOD) in hepatopancreas was not significantly affected by PHB. SOD activity in hemolymph and gill filaments was significantly different from that in control group (P <0.05) The activities of POD and LZM in gills and hepatopancreas reached the highest at 1.0% and 2.5% of PHB concentration, respectively, and the POD and lysozyme (LZM) increased by 7.63-fold and 0.68-fold respectively compared with the control group. Respectively, increased by 0.88 and 0.18 times. The results of ammonia nitrogen stress test showed that the immune gene expression of shrimp was higher than that of the control group after PHB feeding, and the content of MDA in the body was lower than that of the control group. In conclusion, PHB can enhance the non-specific immunity of Litopenaeus vannamei.