College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, Hubei 430070, China; School of Biological Science, Victoria University of Wellington, Wellington 6140, New Zealand.
College of Fisheries, Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education/Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, Hubei 430070, China; Tianjin Fisheries Research Institute, Tianjin 300221, China.
Gene. 2014 Feb 10;535(2):239-49. doi: 10.1016/j.gene.2013.11.027. Epub 2013 Nov 27.
In order to test the hypothesis that the expression levels of GH/IGF axis genes would be negatively related to the expression of the myostatin genes in fish species, we cloned six growth regulating genes including growth hormone receptors-1/-2 (GHRs), insulin-like growth factors-I/-II (IGFs) and myostatins-a/-b (MSTNs) from blunt snout bream (Megalobrama amblycephala). The contents of mRNA transcripts for the six genes were determined in the different tissues of adult and developmental stages for the embryonic and larval periods. The results of quantitative real-time PCR showed that GHRs, IGFs and MSTNs were widely expressed in the tissues we tested, with the relatively lower expression levels in mesonephros, gonad and spleen for the six genes. The analysis of expression correlation coefficients among these six genes showed that GHR 1, GHR 2 and MSTN b were correlated with each other in adult tissues (P<0.01). For the developmental stages, GHR 1 had a similar expression pattern to GHR 2 during the examined periods, both with the highest expression levels at 160 hpf (hours post-fertilization) (P<0.05). IGF-II had higher expression levels than that of IGF-I before 400 hpf (P<0.05), while IGF-I was active after 52 hpf. The maximum of MSTN a and MSTN b mRNA levels were at 24 hpf and 400 hpf, respectively. The analysis of expression correlation coefficients showed that GHR 1, GHR 2, IGF-I, IGF-II and MSTN b were positively correlated with each other during embryonic development (P<0.01). The results from this study suggested that the relationship between GH/IGF axis genes and MSTNs was complex and not absolutely negative correlated in fish species.
为了检验鱼类 GH/IGF 轴基因的表达水平与肌肉生长抑制素基因的表达呈负相关的假说，我们从团头鲂（Megalobrama amblycephala）中克隆了包括生长激素受体-1/-2（GHRs）、胰岛素样生长因子-I/-II（IGFs）和肌肉生长抑制素-a/-b（MSTNs）在内的 6 个生长调节基因。测定了成年鱼和胚胎及幼虫期不同发育阶段的这些基因的 mRNA 转录本含量。定量实时 PCR 结果表明，GHRs、IGFs 和 MSTNs 在我们测试的组织中广泛表达，6 个基因在中肾、性腺和脾脏中的表达水平相对较低。对这 6 个基因的表达相关系数进行分析表明，GHR1、GHR2 和 MSTN b 在成年组织中相互相关（P<0.01）。对于发育阶段，GHR1 在检测期间与 GHR2 具有相似的表达模式，两者在 160 hpf（受精后小时）时表达水平最高（P<0.05）。IGF-II 在 400 hpf 之前的表达水平高于 IGF-I（P<0.05），而 IGF-I 在 52 hpf 后具有活性。MSTN a 和 MSTN b 的最大 mRNA 水平分别出现在 24 hpf 和 400 hpf。表达相关系数分析表明，GHR1、GHR2、IGF-I、IGF-II 和 MSTN b 在胚胎发育过程中呈正相关（P<0.01）。本研究结果表明，鱼类 GH/IGF 轴基因与 MSTNs 之间的关系复杂，并非绝对负相关。
