中文摘要：

本研究以中国明对虾（Fenneropenaeus chinensis）为对象,探讨不同浓度的聚β-羟基丁酸酯（Poly-β-hydroxybutyrate,PHB）对其非特异性免疫相关酶的影响。实验采用单因子浓度梯度法,对健康的中国明对虾投喂添加不同浓度PHB（0、0.5%、1.0%、2.5%、5.0%、10.0%）的饲料,分别对应对照组C和实验组E_（0.5）、E_（1.0）、E_（2.5）、E_（5.0）、E_（10.0）组,饲喂6周,统计每组中国明对虾的死亡率和相对免疫保护率,检测总抗氧化能力（T-AOC）、酸性磷酸酶（ACP）、过氧化物酶（POD）和过氧化氢酶（CAT）、超氧化物歧化酶（SOD）5种酶的活力及丙二醛（MDA）含量与时间、PHB浓度的变化关系。结果显示,实验组的相对免疫保护率随PHB浓度的增加呈现先上升后下降的趋势。E_（1.0）组为最高值,并且与其他各组相比差异显著（P〈0.05）。随PHB浓度的增加,免疫酶活力整体变化趋势为先上升后下降。在时间分布上,饲喂2–3周时,酶活力呈现高水平表达,其中,T-AOC在血清（E_（1.0）、E_（2.5）组）、肝胰腺（E1.0组）;ACP在血清（E_（1.0）、E_（2.5）组）、肝胰腺（E1.0组）;CAT在血清（E_（0.5）、E_（1.0）、E_（2.5）组）、肝胰腺（E_（0.5）、E_（1.0）、E_（10.0）组）;POD在血清和肝胰腺（E_（0.5）、E_（1.0）、E_（2.5）组）;SOD在血清和肝胰腺（E_（1.0）组）以及MDA在血清（E1.0组）、肝胰腺（E_（0.5）,E_（1.0）组）较其他组均具有显著性差异（P〈0.05）。研究表明,PHB添加剂对中国明对虾免疫水平的提高具有促进作用。综合各组和各时间段免疫酶的变化,E_（1.0）为最适浓度组,投喂2–3周时其免疫酶总体具有高水平活力值。

英文摘要：

In the present study, we explored the effect of poly-β-hydroxybutyrate （PHB） on the performance of the immune system in Fenneropenaeus chinensis. This study used single factor concentration gradient method. F. chinensis were fed with baits containing PHB at different concentrations （0, 0.5%, 1.0%, 2.5% and 5.0%）. After six weeks, the mortality and relative immune protective rate of each group was calculated. Moreover, enzyme activities of nonspecific immunity, including the total antioxidant capacity （T-AOC）, the enzyme activities of acid phosphatase （ACP）, peroxidase （POD） and catalase （CAT）, and the content of malondialdehyde （MDA） in muscle, hepatopancreas and serum were analyzed and compared between groups on a weekly basis. The results showed that the PHB had a significant effect on immune performance. With the increase of PHB concentration, the relative immune protective rates in the experimental groups were elevated initially followed by a decline. The group of E1.0 had the highest relative immune protective rate compared with other groups （P〈0.05）. The trend of the enzyme activities were similar to the changes of the relative immune protective rates. On the spatial distribution, the enzyme activities of T-AOC, POD, CAT in serum and ACP in hepatopancreas were the highest. On the temporary distribution, the total enzyme activities reached the highest level after 2–3 weeks of treatments. Among different groups, the groups of E1.0 and E2.5 in serum and E1.0 in hepatopancreas had significant different T-AOC from other groups （P〈0.05）. The ACP activities in serum in the groups of E1.0 and E2.5, and E1.0 in the hepatopancreas were significantly different from other groups （P〈0.05）. During the high level expression period of CAT, serum CAT in E0.5, E1.0, E2.5 groups, hepatopancreas CAT in E 0.5, E1.0, E10.0 groups were significantly different from other groups （P〈0.05）. The serum and hepatopancreas POD activities in E0.5, E1.0, E2.5 groups were significantly