Huazhong Agricultural University
为探讨雌激素受体基因与鱼类雌雄及倍性生长差异之间的相关性，选取雌性生长快于雄性、且四倍体生长快于二倍体的泥鳅为研究对象，首先克隆泥鳅雌激素受体基因，获得ERα （1 821 bp）、ERβ1（1 008 bp）和ERβ2（1 197 bp）的cDNA序列，氨基酸序列比对发现泥鳅ER分别与鲤科鱼类相应亚型具有较高的同源性。采用qRT-PCR检测ER基因在二倍体泥鳅性成熟前后5个关键时期的表达情况及二、四倍体相关组织间的差异表达。结果显示，3个基因在雌雄个体性成熟前后脑、肌肉、肝脏和性腺组织中均存在差异表达，其中ERα 在泥鳅雄性个体脑、肌肉和性腺组织中的表达量显著高于雌性（P<0.05），而在雌性肝脏组织中的表达量普遍高于雄性（P<0.05）；ERβ1和ERβ2在精巢组织中的表达量一直处于较高水平。泥鳅二、四倍性间的比较结果显示，3个ER基因在泥鳅二倍体脑组织中的表达量显著高于四倍体的表达量，且雄性的表达量均高于雌性，其中ERα表达差异最为显著。本研究结果表明，无论是针对倍性生长差异还是雌雄生长差异，ERα均表现为在生长较慢（二倍体、雄性）个体脑组织中有相对高表达，推测脑组织中ERα 基因对鱼类个体生长速度具有一定的抑制调控作用。
In order to investigate the relationship between estrogen receptor genes and growth differences in sexes and ploidy of fish, loach（Misgurnus anguillicaudatus）with females growing faster than males and tetraploids growing faster than diploids were selected as the research object in this study. We firstly cloned the cDNA sequences of three estrogen receptor genes of loach, including ER (1821 bp), ERβ1 (1008 bp) and ERβ2 (1197 bp). Amino acid sequence alignment revealed that loach ER genes have higher homology with corresponding subtypes of carps. Quantitative RT-PCR was used to detect the expression of ER genes in five growth stages of diploid loach as well as diploid and tetraploid adults. The results showed that three genes were differentially expressed in brain, muscle, liver, and gonadal tissues of male and female individuals before and after sexual maturity. Among them, the expression of ERα in brain, muscle and gonad tissues of male individuals was significantly higher than that of females (P<0.05), and the expression in female liver tissues was generally higher than that in males (P<0.05). The expression levels of ERβ1 and ERβ2 in testis tissue were always in high level. Comparison results between different ploidy showed that the expression of three ER genes in the diploid brain tissue were significantly higher than that of the tetraploids, and the expression levels of males were higher than females, with the expression of ERα being the most significant. The results of this study indicated that regardless of the difference between ploidy and sex growth, ERα appears to have relatively high expression in the brain tissue of slower growing (diploid, male) individuals. Therefore, we speculate that the ERα gene in brain tissues might have a certain inhibitory effect on the growth rate of individual fish.