饲料中铜水平对凡纳滨对虾免疫相关基因表达和抗菌能力的影响

在饲料中添加0、30和50 mg Cu/kg饲料的蛋氨酸铜,投喂凡纳滨对虾(Litopenaeus vannamei)7、14和21d,检测对虾体组织铜蓄积、免疫相关基因(Toll受体mRNA和溶菌酶mRNA)表达水平和免疫抗菌能力的变化。结果表明:凡纳滨对虾肝胰腺铜含量随着饲料蛋氨酸铜添加量增加及投喂时间延长而显著增加(P0.05);对虾肌肉的铜含量显著低于肝胰腺的铜含量。饲料中铜水平对凡纳滨对虾肌肉、血淋巴及肝胰腺中溶菌酶活性无显著影响(P0.05)。对虾组织SOD活性因饲料中铜水平和投喂时间变化显著,添加30 mgCu/kg组对虾肌肉、血淋巴和肝胰腺中SOD活性在第21天时显著高于其他两组(P0.05)。饲料中铜水平对凡纳滨对虾鳃组织中溶菌酶mRNA表达水平无显著影响,但显著影响鳃组织Toll受体mRNA表达水平(P0.05)。第7天时凡纳滨对虾Toll受体mRNA表达水平随着饲料铜水平升高而显著升高(P0.05);第14和第21天时,Toll受体mRNA表达水平在摄食添加30 mg Cu/kg组最高。人工急性感染溶藻弧菌(Vibrioalginolyticus)实验表明,第7天时,摄食添加50 mg Cu/kg组凡纳滨对虾全致死时间和半致死时间长于未添加铜组和添加30 mgCu/kg组,但在第14天,摄食添加30 mg Cu/kg组的全致死时间和半致死时间最长。研究表明饲料铜添加水平不但影响组织中铜的蓄积,还影响凡纳滨对虾SOD活性和Toll受体mRNA表达水平,从而影响机体的抗弧菌能力。

EFFECT OF DIETARY COPPER LEVEL ON THE IMMUNITY, VIBRIO-RESISTANT ABILITY,LYSOZYME mRNA AND TOLL RECEPTOR mRNA EXPRESSIONS IN THE WHITE SHRIMP LITOPENAEUS VANNAMEI

Experiments were conducted to determine copper accumulation,SOD and lysozyme activities,immune-related genes(Toll receptor mRNA and Lysozyme mRNA) expression level and Vibrio-resistant ability of white shrimp Litopenaeus vannamei fed the diet with different copper levels(via adding copper methionine 0,30 and 50 mg Cu/kg) for 7d,14d and 21d,respectively.The results indicated that the copper content in hepatopancreas of shrimp significantly increased(P<0.05) with increasing dietary copper and feeding time.Copper content in muscle was always significantly lower than that in hepatopancreas(P<0.05).There was no significant difference in lysozyme activities in hepatopancreas,muscle and haemolymph of the shrimp among different copper treatments(P>0.05),although SOD activity of the shrimp was affected by dietary copper level as well as feeding time.The SOD activities in muscle,haemplymph and hepatopancreas of the shrimp treated with 30 mg Cu/kg diet for 21d were significantly higher than those of the shrimp treated with 50 mg Cu/ kg and 0 mg Cu/kg diets.The dietary copper level did not affect the lysozyme mRNA expression level in shrimp’s gills,but it significantly affected the Toll receptor mRNA expression level in shrimp’s gills(P<0.05).The Toll receptor mRNA expression level in shrimp’s gills increased significantly(P<0.05) with an increasing dietary copper for 7d(P<0.05).While the shrimp treated with 30 mg Cu/kg diet showed the highest Toll receptor mRNA expression level in gills for 14d and 21d.The shrimp treated with 50 mg Cu/kg diet for 7d or with 30 mg Cu/kg diet for 14d displayed the largest half lethal time and complete lethal time when the shrimp were artificially infected with Vibrio alginolyticus.It is therefore suggested that dietary copper level affected not only the accumulation of copper in shrimp tissues,but also the SOD activity and Toll receptor mRNA expression level of the shrimp and finally affected the Vibrio resistance of the shrimp.