动物营养学报    2017, Vol. 29 Issue (5): 1750-1758    PDF    
油脂类型对肉鸡不同组织甘油醛-3-磷酸脱氢酶基因相对表达量的影响
陶亚飞, 陈青, 徐媛媛, 石秀文, 陈文, 黄艳群     
河南农业大学饲料营养河南省工程实验室, 河南农业大学国家家养动物种质资源平台, 郑州 450002
摘要: 本试验旨在探究油脂类型对肉鸡不同组织甘油醛-3-磷酸脱氢酶(GAPDH)基因相对表达量的影响。试验选用240只1日龄的科宝肉鸡母雏,随机分为8个组(4个单一油脂组,分别在饲粮中添加5.00%亚麻油、玉米油、芝麻油和猪油;4个混合油脂组,分别在饲粮中添加2.50%猪油+2.50%玉米油、2.50%猪油+2.50%芝麻油、2.50%亚麻油+2.50%玉米油和2.50%亚麻油+2.50%芝麻油),每组6个重复,每个重复5只鸡。试验期42 d。结果表明:1)组织及油脂类型与组织的交互作用对42日龄肉鸡组织GAPDH基因的相对表达量影响显著(P < 0.05),油脂类型对42日龄肉鸡组织GAPDH基因的相对表达量的影响不显著(P>0.05)。42日龄肉鸡胸肌GAPDH基因的相对表达量显著高于肝脏和腹脂(P < 0.05),是肝脏的37.50~89.50倍,是腹脂的129.54~190.64倍,而42日龄肉鸡的GAPDH基因的相对表达量在肝脏与腹脂之间差异不显著(P>0.05);玉米油组胸肌中GAPDH基因的相对表达量显著高于猪油组(P < 0.05)。2)21日龄肉鸡肝脏GAPDH基因的相对表达量显著或极显著高于42日龄(P < 0.05或P < 0.01)。3)油脂组合及油脂组合与日龄的交互作用对肉鸡肝脏GAPDH基因相对表达量的影响均不显著(P>0.05),但日龄对肉鸡肝脏GAPDH基因相对表达量的影响显著(P < 0.05)。由此可见,油脂类型对肉鸡GAPDH基因的相对表达量的影响呈现组织间的差异,玉米油可提高胸肌GAPDH基因的相对表达量。42日龄肉鸡胸肌GAPDH基因的相对表达量显著高于肝脏和腹脂,21日龄肉鸡肝脏GAPDH基因的相对表达量显著高于42日龄。
关键词: 肉鸡     油脂     GAPDH     基因表达    
Effects of Oil Types on Glyceraldehyde-3-Phosphate Dehydrogenase Gene Relative Expression Level in Different Tissues of Broilers
TAO Yafei, CHEN Qing, XU Yuanyuan, SHI Xiuwen, CHEN Wen, HUANG Yanqun     
Henan Agricultural University National Germplasm Resoueces Platform for Animals, Feed Nutrition Engineering Laboratory of Henan Province, Henan Agricultural University, Zhengzhou 450002, China
Abstract: This experiment was conducted to study the effects of oil types on glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene relative expression level in different tissues of broilers. A total of 240 one-day-old female Cobb broilers were selected and randomly assigned to 8 groups (four single oil groups were fed diets added with 5.00% linseed oil, corn oil, sesame oil and lard oil, respectively; four oil combination groups were fed diets added with 2.50% lard oil+2.50% corn oil, 2.50% lard oil+2.50% sesame oil, 2.50% linseed oil+2.50% corn oil and 2.50% linseed oil+2.50% sesame oil, respectively) with 6 replicates per group and 5 broilers per replicate. The experiment lasted for 42 days. The results showed as follows: 1) the relative expression level of GAPDH gene in broiler tissues was significantly affected by tissues and the interaction between oil types and tissues (P < 0.05), however, the effects of oil types were not significant (P>0.05). The relative expression level in pectorals of GAPDH gene of 42-day-old broilers was significantly higher than that in liver and abdominal fat (P < 0.05), the relative expression level of GAPDH gene in liver was 37.50 to 89.50 and 129.54 to 190.64 times than that in liver and abdominal fat, respectively, however, the relative expression level of GAPDH gene between liver and abdominal fat was not significant (P>0.05). The relative expression level of GAPDH gene in corn oil group was significantly higher than that in sesame oil group in pectorals (P < 0.05). 2) The relative expression level of GAPDH gene in liver of 21-day-old broilers was significantly higher than that of 42-day-old broilers (P < 0.05 or P < 0.01). 3) The relative expression level of GAPDH gene in liver of broilers was significantly affected by days of age (P < 0.05), however, the effects of oil combination and the interaction between oil combination and days of age were not significant (P>0.05). In conclusion, the effect of oil types on the relative expression level of GAPDH gene in broilers shows difference among different tissues, corn oil can improve the relative expression level of GAPDH gene in pectorals. The relative expression level in pectorals of GAPDH gene of 42-day-old broilers is significantly higher than that in liver and abdominal fat, and the relative expression level of GAPDH gene in liver of 21-day-old broilers is significantly higher than that of 42-day-old broilers.
Key words: broilers     oil     GAPDH     gene expression    

甘油醛-3-磷酸脱氢酶 (glyceraldehyde-3-phosphate dehydrogenase,GAPDH) 是动物能量代谢途径的关键代谢酶,由4个分子质量为30~40 ku的亚基组成,分子质量为146 ku[1]。最初对GAPDH的研究主要集中在其在糖酵解过程中的作用,GAPDH作为糖酵解过程中的关键酶之一[2-4],在细胞膜、细胞质、细胞核上均有分布。随着对GAPDH研究的深入,发现该酶还具有一些与糖酵解功能无关的生物活性,例如,在生物膜上,GAPDH参与膜运动、促进膜融合等[5];在细胞质中,GAPDH有保护细胞、催化微管聚合等功能[6];在细胞核内,GAPDH参与tRNA出核、DNA修复[7];在一些神经性疾病上,GAPDH参与细胞凋亡以及与年龄相关的神经性疾病[8];研究表明,GAPDH还具有磷酸转移酶/激酶的活性[9]GAPDH基因具有高度保守的种属序列并且广泛存在于众多生物体中,几乎在所有组织中都高水平表达。在分子生物学研究方法上,GAPDH基因常被作为管家基因,广泛用作RNA水平和蛋白质水平下基因表达研究的标准化内参。

玉米油和芝麻油含有较高的亚油酸和油酸,是n-6脂肪酸的代表[10-11];亚麻籽油的n-6/n-3多不饱和脂肪酸 (PUFA) 的比值 (约为0.34 : 1.00) 远远低于其他油脂,是n-3脂肪酸的代表[12-13];猪油是富含单不饱和脂肪酸的动物油,其油酸含量高达48.70%。已有研究表明,在肉鸡饲粮中适量添加油脂可以满足肉鸡快速生长对能量的需要,改善饲粮口感和提高饲粮利用率[14]。油脂类型会影响动物脂类代谢及脂肪酸合成酶 (FAS) mRNA的表达[15]。但尚未见油脂类型对肉鸡GAPDH基因表达效应的系统报道。本文主要研究单一油脂及其组合对不同日龄肉鸡在不同组织中GAPDH基因表达量的影响。

1 材料与方法 1.1 试验动物及试验设计

本试验选用240只1日龄科宝肉鸡母雏,随机分为8组,每组6个重复,每个重复5只鸡。试验鸡采用笼养,每笼5只鸡,自由采食和饮水,免疫程序按常规进行。饲粮参照NRC (1994) 肉鸡的营养需要配制,分为1~3周龄和4~6周龄2个阶段。试验期42 d。4个单一油脂组分别在饲粮中添加5%的亚麻油、玉米油、芝麻油和猪油,其饲粮组成及营养水平见表 1;4个混合油脂组包含2个猪油混合组 (饲粮中添加2.5%猪油+2.5%玉米油、2.5%猪油+2.5%芝麻油) 和2个植物油混合组 (饲粮中添加2.5%亚麻油+2.5%玉米油、2.5%亚麻油+2.5%芝麻油),其饲粮组成及营养水平见表 2

表 1 单一油脂组饲粮组成及营养水平 (风干基础) Table 1 Composition and nutrient levels of diets of single oil groups (air-dry basis)
表 2 混合油脂组饲粮组成及营养水平 (风干基础) Table 2 Composition and nutrient levels of diets of oil combination groups (air-dry basis)
1.2 样品采集

分别于21、42日龄时,从每组各重复随机挑选1只肉鸡屠宰,在无菌条件下取肝脏、胸肌和腹脂。所取样品均用焦炭酸二乙酯 (DEPC) 水清洗后,放入液氮速冻,-80 ℃保存。

1.3 总RNA提取和反转录

组织样品总RNA的提取参照TaKaRa的Trizol试剂盒使用说明书 (取50~10 mg的组织)。微量分光光度计 (NanoDrop 2 000 UV spectrophotometer,Thermo Scientific,德国) 分析提取的RNA浓度和纯度;琼脂糖凝胶电泳、凝胶成像分析系统 (AlphaImager) 上照相分析所提取RNA的完整性。反转录反应参照试剂盒使用说明书进行操作 (PrimeScript® RT Reagent Kit with gDNA Eraser,TaKaRa,大连),该反转录试剂盒可以去除提取RNA中的残余基因组DNA。反应液 (总RNA 2.0 μg) 置于冰上进行操作,反应体系为20 μL。瞬时离心混匀后将反应液放到PCR仪器中,37 ℃反应15 min,85 ℃反应5 s,-20 ℃保存备用。

1.4 引物设计

根据红色原鸡的GAPDH基因序列 (GenBank登录号:NM_204305.1),用Oligo 6.0软件设计荧光定量PCR所用的检测引物,并由上海生物工程技术服务有限公司合成。PCR扩增片段长度为98 bp。荧光定量PCR引物见表 3

表 3 荧光定量PCR引物 Table 3 The primers of fluorescent quantitative PCR
1.5 荧光定量PCR反应条件

参照张雯雯等[16]文献,运用探针法荧光定量PCR进行基因的定量表达分析:反应体系为25.0 μL,包括1.0 μL cDNA (0.1 μL总RNA)、0.5 μL上游引物 (12.5 μmol/L)、0.5 μL下游引物 (12.5 μmol/L)、2.5 μL TaqManTM探针、0.5 μL RoxⅡ、3.5 μL镁离子 (Mg2+,25 mmol/L)、12.5 μL 2×Mix (包含1.5 mmol/L Mg2+)、4.0 μL超纯水;荧光定量PCR反应条件为95 ℃预变性2 min;40个循环的95 ℃变性15 s;60 ℃退火1 min。每个样品设置3个重复。纯化的PCR产物采用微量分光光度计 (NanoDrop 2000 UV spectrophotometer) 测定浓度后,进行梯度稀释 (10-4、10-5、10-6、10-7、10-8、10-9和10-10),用于建立每板的标准曲线。每板均设阴性对照。参照Bustin[17]报道方法,本研究采用微量定量仪测定RNA的浓度,反应中添加等量的RNA和cDNA进行每个样品的均一化处理。

1.6 数据统计和分析

首先,把每个样本的GAPDH拷贝数转换成相对表达量。GAPDH基因的相对表达量=样本拷贝数/42日龄平均拷贝数最低组 (5.00%芝麻油组在腹脂组织的表达值) 平均值。试验数据用SAS 8.1统计软件中的ANOVA (GLM) 过程进行单变量两因素方差分析, 检测油脂类型与组织、油脂类型与日龄、油脂组合与日龄对肉鸡GAPDH基因的相对表达量的效应。以P < 0.05为差异显著,P < 0.01为差异极显著。

2 结果与分析 2.1 单一油脂对42日龄肉鸡不同组织中GAPDH基因的相对表达量的影响

表 4可知,42日龄时,组织以及油脂类型与组织的交互作用显著影响了肉鸡不同组织中GAPDH基因的相对表达量 (P < 0.05),油脂类型对肉鸡GAPDH基因的相对表达量的影响不显著 (P>0.05)。肉鸡不同组织中GAPDH基因的相对表达量表现为胸肌>肝脏>腹脂。在不同单一油脂组中,胸肌GAPDH基因的相对表达量均显著高于肝脏和腹脂 (P < 0.05),是肝脏的37.50~89.50倍,是腹脂的129.54~190.64倍,而GAPDH基因的相对表达量在肝脏和腹脂之间差异不显著 (P>0.05)。在胸肌中,玉米油组GAPDH基因的相对表达量显著高于猪油组 (P < 0.05),而在肝脏和腹脂中,不同油脂类型组中GAPDH基因的相对表达量均无显著差异 (P>0.05)。以上结果表明,肉鸡GAPDH基因的相对表达量具有明显的时空表达特性,受肉鸡不同组织的显著影响。

表 4 单一油脂对42日龄肉鸡不同组织中GAPDH基因的相对表达量影响 Table 4 Effects of single oil on the relative expression level of GAPDH gene in different tissues of 42-day-old broilers
2.2 单一油脂类型对不同日龄肉鸡肝脏中GAPDH基因的相对表达量的影响

表 5可知,日龄显著影响了肉鸡肝脏中GAPDH基因的相对表达量 (P < 0.05),油脂类型以及油脂类型与日龄的交互作用对肉鸡肝脏中GAPDH基因的相对表达量的影响不显著 (P>0.05)。亚麻油组、玉米油组、芝麻油组和猪油组21日龄肉鸡肝脏中GAPDH基因的相对表达量均显著或极显著高于42日龄 (P < 0.05或P < 0.01),是42日龄肉鸡肝脏中GAPDH基因的相对表达量的2.46~4.15倍。但21和42日龄肉鸡肝脏中GAPDH基因的相对表达量在不同油脂类型之间均无显著差异 (P>0.05)。以上结果表明,肉鸡肝脏中GAPDH基因的相对表达量受肉鸡日龄的显著影响。

表 5 单一油脂对不同日龄肉鸡肝脏中GAPDH基因的相对表达量的影响 Table 5 Effects of single oil on the relative expression level of GAPDH gene in liver of broilers at different days of age
2.3 混合油脂对不同日龄肉鸡肝脏中GAPDH基因的相对表达量的影响

表 6表 7可知,油脂组合以及日龄与油脂组合的交互作用对肉鸡肝脏中GAPDH基因的相对表达量影响不显著 (P>0.05),但日龄仍显著影响了肉鸡肝脏中GAPDH基因的相对表达量 (P < 0.05)。与单一油脂一样,21日龄肉鸡肝脏中GAPDH基因的相对表达量均显著或极显著高于42日龄 (P < 0.05或P < 0.01),是肉鸡肝脏中GAPDH基因的相对表达量的2.46~3.57倍。

表 6 亚麻油混合油脂对肉鸡肝脏中GAPDH基因的相对表达量的影响 Table 6 Effects of mixed linseed oils on the relative expression level of GAPDH gene in liver of broilers
表 7 猪油混合油脂对肉鸡肝脏中GAPDH基因的相对表达量的影响 Table 7 Effects of mixed lard oils on the relative expression level of GAPDH gene in liver of broilers
3 讨论

本研究发现,肉鸡GAPDH基因的相对表达量在不同组织间有显著的差异,胸肌是其优势表达部位。在肉鸡肝脏中,GAPDH基因的相对表达量也随日龄呈现显著变化,表明肉鸡GAPDH基因具有明显的时空表达特性。Barber等[18]研究表明,人GAPDH基因在组织间的表达也呈现显著差异,在骨骼肌中的相对表达量最高,而在乳腺中的相对表达量最低,两者相差15倍。

Lowe等[19]研究报道,老龄 (37月龄) 大鼠的GAPDH基因和蛋白质水平在骨骼肌的快肌中均显著低于幼龄 (9月龄) 大鼠,而在慢肌之间则无显著差异,显示快肌的糖酵解能力随着年龄的增长而下降。Slagboom等[20]研究发现,36月龄雌性大鼠脾脏GAPDH基因的相对表达量显著高于24月龄,而在肝脏和脑部GAPDH基因的相对表达量没有出现伴随年龄的明显变化。Mozdziak等[21]研究发现,7日龄时鸡胸肌中GAPDH基因的相对表达量显著高于其他不足7日龄的小鸡。本试验中21日龄肉鸡肝脏中GAPDH基因的相对表达量显著或极显著高于42日龄,显示肉鸡肝脏的糖酵解能力随着肉鸡日龄的增长而下降。日龄对动物GAPDH基因的相对表达量的影响因物种、组织或肌肉类型的不同而异。

Hanke等[22]研究发现,在野兔骨骼肌细胞培养过程中,低浓度的葡萄糖可以直接抑制GAPDH启动子的活性,从而降低其转录水平和酶活性。Mozdziak等[21]报道,3日龄肉鸡胸肌GAPDH基因的相对表达量以饲粮饲喂组显著高于禁饲组,表明营养状态可以改变GAPDH基因的转录水平。而本研究发现5%的玉米油上调了胸肌中GAPDH基因的相对表达量,而油脂类型和油脂组合对42日龄肉鸡肝脏中GAPDH基因的相对表达量无显著影响,显示油脂以机体组织特异性和种类特异性的方式影响GAPDH的转录水平。

近几年来,越来越多的研究者发现GAPDH在作为内参基因时表现出不稳定的现象[23-24],其表达量在转录或转录后受到其他因子调节,基因水平和蛋白质水平会随着不同刺激而变化[20]。因此在分子生物学研究中应谨慎选择GAPDH基因作为内参基因。

4 结论

① 油脂类型对肉鸡GAPDH基因的相对表达量的影响呈现组织间的差异,玉米油可提高42日龄肉鸡胸肌GAPDH基因的相对表达量。

② 42日龄肉鸡胸肌GAPDH基因的相对表达量显著高于肝脏和腹脂。

③ 21日龄肉鸡肝脏中GAPDH基因的相对表达量显著或极显著高于42日龄。

致谢: 感谢河南农业大学牧医工程学院王志祥教授对该文稿所提出的宝贵意见。
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