谷氨酰胺对半滑舌鳎稚鱼非特异性免疫相关酶活力和低氧应激后HIF-1α表达的影响

EFFECTS OF DIETARY GLUTAMINE ON ACTIVITIES OF NON-SPECIFIC IMMUNE RELATED ENZYMES AND HIF-1α EXPRESSION AFTER HYPOXIA OF HALF-SMOOTH TONGUE SOLE POST LARVAE

为探讨饲料中谷氨酰胺对半滑舌鳎稚鱼非特异性免疫以及低氧应激后HIF-1α表达的影响,实验共设计了4种谷氨酰胺添加量分别为0、0.5%、1.0%和2.0%的等氮等脂微颗粒饲料(游离谷氨酰胺测定值分别为0.03%、0.46%、0.91%和1.73%),饲喂35日龄半滑舌鳎稚鱼[平均干重(10.64±0.86)mg]。每天饱食投喂5次,养殖周期30d,养殖结束后进行低氧应激实验。研究结果表明,谷氨酰胺添加量为0.5%时半滑舌鳎稚鱼鱼体溶菌酶(LZM)活力显著高于未添加组(P<0.05)。饲料中不同谷氨酰胺水平对鱼体总一氧化氮合酶(TNOS)活力和诱导型一氧化氮合酶(i NOS)活力没有显著影响(P>0.05)。实验克隆了半滑舌鳎低氧应激关键基因——缺氧诱导因子1α(HIF-1α),得到749 bp半滑舌鳎HIF-1α核心序列,系统进化树分析表明半滑舌鳎HIF-1α氨基酸序列与大部分鱼类具有较高同源性。定量PCR结果显示,饲料中谷氨酰胺水平对低氧应激后半滑舌鳎稚鱼内脏团HIF-1α表达量未产生显著影响(P>0.05)。综上所述,在饲料中添加谷氨酰胺能够显著增强半滑舌鳎稚鱼鱼体溶菌酶活力(P<0.05),提高非特异性免疫水平。

To investigate effects of dietary glutamine on activities of non-specific immune related enzymes and antihypoxiastress capacity of half-smooth tongue sole (Cynoglossus semilaevis Günther) post larvae, four isonitrogenousand isolipidic experimental diets supplemented with 0, 0.5%, 1.0% and 2.0% gluta-mine (with dietary free glutamineestimated to be about 0.03%, 0.46%, 0.91% and 1.73%) were formulated and fed 5 times per day to C. semilaevis postlarvae (35 days after hatching, 10.64±0.86 mg dry weight) for 30 days before hypoxia stress test. Results revealted thatthe 0.5% glutamine supplemented diet significantly increased activities of lysozyme in fish whole body compared to thecontrol group (P<0.05), but different glutamine level did not impact the activities of total nitric oxide synthase and induciblenitric oxide synthase in fish whole body (P>0.05). C. semilaevis HIF-1α gene were cloned and 749 bp partialcDNA sequence were obtained, which shared high identities with many other fish species. Quantitative Real-time PCRshowed that glutamine supplementation did not regulate the expressions of HIF-1α in fish after hypoxia stress (P>0.05).In summary, dietary glutamine could enhacne the activities of LZM and the non-specific immunity of C. semilaevispost larvae.