半胱胺盐酸盐和LHRH-A对黄鳍鲷IGF-Ⅰ基因表达和生长的影响

本文以黄鳍鲷 (Sparuslatus)为研究对象 ,利用GeneRaceTM 技术 ,从其肝组织中克隆出类胰岛素生长因子 (IGF Ⅰ )cDNA ,并应用半定量RT PCR方法研究了半胱胺盐酸盐 (Cysteaminehydrochloride)和LHRH A对其肝组织IGF Ⅰ基因表达的影响。黄鳍鲷IGF ⅠcDNA全长为 84 0bp ,编码 185aa多肽 ;序列分析表明 ,黄鳍鲷IGF Ⅰ基因编码的氨基酸序列与金鱼的同源性为 75 8% ,与牙鲆的同源性为 86 5 % ,与同属鲷科的黑鲷同源性高达 10 0 % ,证明鱼类类胰岛素生长因子是非常保守的 ,E区域分析结果表明黄鳍鲷IGF Ⅰ属Ea 4型。在饲料中投喂CSH、LHRH A等添加剂 ,实验组黄鳍鲷鱼种的相对生长率、垂体GH含量、肝脏IGF ⅠmRNA水平均显著高于对照组。以上结果提示 :CSH、LHRH A能促进黄鳍鲷生长激素的合成和IGF Ⅰ基因的表达 ,从而促进鱼种的生长

Effect of cysteamine hydrochloride and luteininzing hormone-releasing hormone analog on the growth and the expression of IGF-Ⅰ mRNA in the yellow-fin porgy Sparus latus

This paper was focused on the effects of cysteamine (CSH) and luteininzing hormone-releasing hormone analog (LHRH-A, D-Ala6, Pro9-Net-LHRH) on the expression of IGF-Ⅰ mRNA and the growth in juvenile yellow-fin porgy Sparus latus.IGF-ⅠcDNA of yellow-fin porgy was cloned from the liver using GeneRacerIM kit (Invitrogen), The IGF-Ⅰ cDNA is 840 bp in length, and the open reading frame encodes a putative protein of 185 amino acids.The comparison of the deduced amino acid sequence indicated that yellow-fin porgy IGF-Ⅰshared 75.2% identity with zebrafish, 75.8% with goldfish, 84.7% with trout, 86.5% with turbot, 96.8% with grouper, and 100% with seabream.The analysis of the E domain showed that porgy IGF-Ⅰ belonged to type Ea-4.The experiments were conducted from August to October 2003 for 45 days and the effects of CSH and LHRH-A administered in the diet on GH, growth, IGF-Ⅰ mRNA were determined.Healthy juvenile yellow-fin porgy (body weight 8.9±2.5 g) were maintained in outdoor cages (15 m×1.5 m×1.2 m) in seawater under natural photoperiod.Water temperatures varied from 23 to 28° C.and the dissolved oxygen, pH and salinity were around 6.0 mg/L, 8.0 and 10‰, respectively.After acclimation of two weeks, the yellow-fin porgy were randomly and equally allocated to cages and fed formulated diet twice a day to satiation.The IGF-ⅠmRNA expression in the liver was examined with semi-quantitative RT-PCR, and GH concentrations in the pituitary were assayed with heterogenous RIA.The results showed that CSH (1.25 mg/g diet) and LHRH-A (10 μg/g diet) alone or in combination significantly increased the pituitary GH contents and the hepatic IGF- I mRNA levels of yellow-fin porgy as compared to that of the control group at the end of the experiment, The relative somatic growth rates (RSGR) of yellow-fin porgy fed with CSH and LHRH-A alone or in combination for 45 days were significantly higher than those of the control group.The relative linear growth rates (RLGR) of yellow-fin porgy fed with CSH or the combination of CSH and LHRH-A for 30 days were significantly higher than those of controls.After 45 days of feeding, RLGR levels of porgy fed CSH and LHRH alone or in combination were significantly higher than those of the control group, and the RLGR levels of porgy fed with the combination of CSH and LHRH-A were significantly higher as compared to the group fed LHRH-A alone.Taken together, these results indicate that both CSH and LHRH-A could promote the growth of yellow-fin porgy, and the activation of the GH-IGF axis may be involvedActa Zoologica Sinica 51(1):108-116,2005].