黄颡鱼重组生长激素的制备及对其鱼苗生长的影响

THE PREPARATION OF RECOMBINANT GROWTH HORMONE AND ITS EFFECTS ON THE GROWTH OF JUVENILE IN PELTEOBAGRUS FULVIDRACO

生长激素在渔业生产中具有重要的应用价值,通过制备黄颡鱼(Pelteobagrus fulvidraco)同源重组生长激素并用于促生长实验,从而为建立鱼苗快速培育方法提供理论依据。根据已知黄颡鱼生长激素(Pf GH)基因c DNA序列,利用IPTG诱导和SDS-PAGE分析方法,Western印迹表明在IPTG终浓度1.0 mmol/L、温度17℃和培养时间14h的条件下,黄颡鱼生长激素基因在大肠杆菌中大量表达,获得重组生长激素蛋白。然后,随机选取黄颡鱼分为4组放入室内水族箱中进行养殖,每箱35尾,体质量为(0.85±0.01)g,每组设3个平行,水体循环净化。用制备的重组生长激素浓度分别为0、1、5和10 mg/L对黄颡鱼进行浸泡处理,每周一次,0为对照组。在养殖4周后,对各组增重率和特定生长率进行比较,结果表明1 mg/L组增重率和特定生长率分别比对照组提高了29.67%(P<0.05)和11.90%(P<0.05),5 mg/L组增重率和特定生长率分别比对照组提高了21.32%(P<0.05)和8.83%(P<0.05),各组间体成分等均无明显差异。停用生长激素4周后,各组黄颡鱼的生长性能、体成分等均无显著差异。研究表明通过原核表达可以获得黄颡鱼重组生长激素,用于促进鱼苗生长培育的最佳浸泡浓度为1 mg/L。

In this study, the mature peptide-encoding cDNA sequence of the growth hormone of Pelteobagrus fulvidraco （PfGH） was inserted into the prokaryote expression vector pET-28a （＋）. The recombinant plasmid of pET-PfGH was then transfected into Escherichia coli BL21 （DE3） and was induced by IPTG. The SDS-PAGE results showed that E. coli BL21 （DE3） with pET-PfGH expressed a specific fusion protein with a molecular weight of 21 KD. The western blot test revealed that the protein contained a 6-His tag. PfGH was abundantly expressed in E. coli cultured at 17℃ for 14 hours with the final IPTG concentration of 1.0 mmol/L. After ultrasonic disruption the soluble recombinant protein was reco-vered and purified, and was then applied to juvenile Pelteobagrus fulvidraco. The subjects with the average weight of （0.85±0.01） g were randomly divided into four groups and were raised in an indoor aquarium. Every group had three re-peats with 35 fish in each. The experiments were conducted in the interior circulation water purification system. During the 4-week feeding trial, four groups were soaked in liquid containing the recombinant GH at different concentrations of 0 （the control）, 1 （group 1）, 5 （group 2） and 10 mg/L （group 3） respectively, and the soaking frequency was once a week. At the end of the trial, our results showed that compared to the control group, the weight gain rate （WG） and the specific growth rate （SGR） of group 1 increased by 29.67%（P〈0.05） and 11.90%（P〈0.05） respectively;the WG and SGR of group 2 in-creased by 21.32%（P〈0.05） and 8.83%（P〈0.05） respectively. However, the body composition was not significantly dif-ferent between the four groups. Furthermore, no significant difference was detected in the growth performance and the body composition between the four groups in 4 weeks after the cease of growth hormone treatment.