We cloned the cDNAs of zebrafishnr1d4a andnr1d4b, performed sequence alignment and phynogenetic analyses, and characterized the expression patterns and their transcriptional responses to several environmental stresses by using real time quantitative RT-PCR (qPCR). The results indicated that zebrafishnr1d4a andnr1d4b genes are paralogs generated by genomic duplication. The DNA binding domain and ligand binding domain of these two paralogs are highly conserved, but these genes possess distinct expression patterns. The abundance ofnr1d4a mRNA was quite low during the early stages of embryogenesis and markedly increased at 72hpf; however,nr1d4b was found to be ma-ternally expressed and the mRNA abundance decreased at 6hpf and significantly increased at 72hpf as well. As for tis-sue-specific expression, the highest expression of zebrafishnr1d4a was found in brain and kidney, followed by gill, ovary, testis and eye, and liver was the organ with the lowest expression. The highest abundance ofnr1d4b mRNA was found in ovary, followed by testis and brain, and the lowest expression was found in intestine and heart. The expression of both nr1d4a andnr1d4b could be induced by multiple environmental stresses. The up-regulation of zebrafishnr1d4a andnr1d4b could be detected at as early as 0.5h after exposed to cold stress (16℃). However, the inductive effect of cold stress decreased and gradually disappeared after 6h of exposure. In addition to cold stress, the expression of ze-brafish nr1d4a andnr1d4b was also induced by heavy metal (2μmol/L cadmium), hypoxia (5% oxygen) and salinity (5‰), indicating the involvement of these genes in the acclimation to various environmental stresses. Thus, these find-ings have laid the foundation for further investigation ofnr1d4a andnr1d4b functions and mechanisms underlying the regulation of their expression in fish.%研究获得了斑马鱼 nr1d4a 和 nr1d4b 基因的 cDNA,进行了序列比对和系统进化分析,并采用实时定量RT-PCR (qPCR)方法研究了其表达模式及对不同环境刺激的转录反应。研究发现,斑马鱼nr1d4a和nr1d4b是由基因复制产生的旁系同源基因,具有高度保守的DNA结合结构域和配体结合结构域。斑马鱼nr1d4a和nr1d4b的表达模式具有明显的差别。nr1d4a在胚胎发育早期的表达量很低,72 hpf时开始显著升高；而nr1d4b具有较高水平的母源性表达,6 hpf时的表达量明显降低,但也在72 hpf显著回升。nr1d4a在脑和肾脏中表达量最高,其次是鳃、卵巢、精巢和眼,在肝脏中的表达量最低； nr1d4b 在卵巢中表达量最高,其次是精巢和脑,在肠道和心脏中表达量最低。斑马鱼nr1d4a和nr1d4b都能被多种环境刺激瞬时诱导表达。16℃低温处理0.5h就能显著诱导斑马鱼nr1d4a和nr1d4b基因的表达,但处理6h后其诱导效应开始下降并逐渐消失。除低温外,重金属(2μmol/L镉)、缺氧(5%氧气)和盐度(5‰)处理均能瞬时诱导nr1d4a和nr1d4b的表达,说明 nr1d4a和nr1d4b基因可能参与斑马鱼对多种环境刺激的适应性反应。研究为深入揭示鱼类 nr1d4a和nr1d4b基因的生物学功能及其表达调控机制奠定了基础。
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