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Abstract：
Thyroid hormones (THs) play a pivotal role in many physiological functions in vertebrates, including fish. Their effects are mediated by thyroid hormone receptors (TRs), which are members of the nuclear hormone receptor superfamily. In this study, full-length cDNA sequences of TRs from yellow catfish Pelteobagrus fulvidraco and Javelin goby Synechogobius hasta were cloned and their mRNA tissue expression profiles were determined. In P. fulvidraco, the validated cDNAs encoding for TRα and TRβ were 1789 and 1848 bp in length, encoding peptides of 401 and 378 amino acid residues, respectively. In addition, a TRβ spliced variant (named P. fulvidraco-TRβv), containing a 60-bp insertion, was detected. In S. hasta, cDNAs encoding for TRαA, TRαB and TRβ were 1827, 2295 and 2258 bp in length, encoding peptides of 401, 409 and 393 amino acid residues, respectively. The phylogenetic analysis revealed that TRα and TRβ cDNAs grouped into two separate clusters with other vertebrate counterparts and two TRα sequences grouped separately, suggesting that the two TRαs derived from paralogous genes that might arise during a teleost-specific genome duplication event. All TR mRNAs were detected in various tissues sampled. The mRNA levels of both TRα and TRβ from P. fulvidraco were the highest in brain, followed by liver, and lowest in heart, intestine, muscle, gill and spleen. However, in S. hasta, TRαA, TRαB and TRβ showed the highest mRNA levels in brain and lowest in muscle. Identification and mRNA tissue expression of TR genes from P. fulvidraco and S. hasta provide an initial step towards understanding their biological roles in the two fish species.
摘要：
甲状腺激素（THs）在脊椎动物的许多生理功能中起着关键作用，包括鱼。它们的作用是由甲状腺激素受体（TRs）介导的，它们是核激素受体超家族的成员。在这项研究中,克隆了黄of鱼Pelteobagrusfulvidraco和标枪gobySynnechogobiushasta的TRs的全长cDNA序列，并确定了它们的mRNA组织表达谱。在P.Fulvidraco，经过验证的编码TRα和TRβ的cDNA长度为1789和1848bp，编码401和378个氨基酸残基的肽，分别。此外,TRβ剪接变体（命名为P.fulvidraco-TRβv），包含60bp的插入，被检测到。在S.hasta，编码TRαA的cDNA，TRαB和TRβ长度分别为1827、2295和2258bp，编码401、409和393个氨基酸残基的肽，分别。系统发育分析表明，TRα和TRβcDNA与其他脊椎动物的对应物分为两个单独的簇，两个TRα序列分别分组，这表明这两个TRα源自硬骨鱼特异性基因组复制事件期间可能出现的旁系同源基因。在取样的各种组织中检测到所有TRmRNA。Fulvidraco的TRα和TRβ的mRNA水平在大脑中最高，其次是肝脏，心脏最低，肠,肌肉，ill和脾。然而,在S.hasta,TRαA,TRαB和TRβ的mRNA水平在脑中最高，在肌肉中最低。来自P.fulvidraco和S.hasta的TR基因的鉴定和mRNA组织表达为了解它们在两种鱼类中的生物学作用提供了第一步。
