黄颡鱼促甲状腺激素受体基因的克隆及其对饲料中添加碘化钾的表达反应

摘要

The aims of the present study were to characterize the cDNA full-long sequence of thyrotropin recep-tor ( TSHR) gene of yellow catfish ( Pelteobagrus fulvidraco) , and to determine the differential expression of TSHR gene in different tissues.In addition, the effects of dietary potassium iodide ( KI) addition on TSHR gene expression and growth performance of yellow catfish were revealed.The rapid amplification of cDNA ends ( RACE) technique was used to clone the cDNA full-long sequence of TSHR gene.Moreover, RT-qPCR technique was used to determine the relative expression level of TSHR gene.The KI adding levels were set to be 0 ( control) , 10, 50 and 100 mg/kg in four experimental diets, which were fed to yellow catfish for 27 days.The results showed as follows: the cDNA full-length sequence of TSHR gene was obtained, and it was 2 786 bp, including a complete open reading frame of 2 238 bp encoded a 745 amino acid residues.Blast on-line analysis indicated that the amino acid sequence of yellow catfish displayed 60%to 87%identity as com-pared with other known fish species.The analysis results of tissue differential expression of TSHR gene indica-ted that the highest relative expression level was in thyroid, followed by liver, muscle and intestine.The results of feeding trial were showed that the relative expression level of TSHR gene in thyroid in 100 mg/kg group was significantly higher than that in other groups ( P<0.05) , and the weight gain, specific growth rate and feed conversion ratio in 50 and 100 mg/kg groups were significantly higher than those in control group ( P<0.05) . The results in this study imply that the dietary KI in the appropriate amount not only affects the expression of TSHR gene, but also promote the growth of yellow catfish effectively.%本试验旨在得到黄颡鱼促甲状腺激素受体（ TSHR）基因的cDNA全长序列，同时掌握其组织表达差异，并揭示饲料中添加碘化钾对黄颡鱼甲状腺TSHR基因表达及生长性能的影响。采用cDNA末端快速扩增（ RACE）技术克隆TSHR基因cDNA全长序列，再应用荧光定量PCR技术检测 TSHR 基因的相对表达量，并制备了碘化钾添加量分别为0（对照）、10、50和100 mg／kg的4种试验饲料进行为期27 d的黄颡鱼养殖试验。结果显示：本试验成功克隆得到长度为2786 bp的TSHR基因cDNA的全长序列，其中开放阅读框2238 bp，编码745个氨基酸，Blast程序分析表明黄颡鱼TSHR氨基酸序列与其他已知鱼类的相似性为60％～87％。组织表达分析结果表明TSHR基因在甲状腺组织中的相对表达量较高，其次是肝脏、肌肉和肠道。养殖试验结果表明，100 mg／kg组甲状腺TSHR基因相对表达量显著高于其他各组（ P＜0．05），50和100 mg／kg组的增重、特定生长率和饲料系数显著优于对照组（ P＜0．05）。由此得出，饲料中添加适量的碘化钾不仅影响TSHR基因的表达，还能有效促进黄颡鱼的生长。