环境污染物对斑马鱼早期胚胎转座子转录活性的影响

Effects of environmental pollutants on transcription activity of transposons during the early embryonic development of zebrafish(Danio rerio)

转座子在生物基因组中占据重要的组成部分,是基因组中可移动和扩展的重要元件,其转座活性受外界环境因子调控。为了探讨环境应激对基因组转座子表达活性的影响,用环境污染物二噁英(TCDD)和重金属Cu^(2+)或Cd^(2+)处理斑马鱼早期胚胎,通过荧光定量PCR(q RT-PCR)比较处理前后9种结构完整的转座子转录活性变化,这9种转座子分别是DNA转座子Tc1家族的Tc-a、Tc-b、Tc-c、Tc-d、Tc-e,反转录转座子病毒家族ZB-ERV-1、ZB-ERV-2、反转录转座子LINE家族L1-323和L1-21。结果发现,TCDD使8个转座子转录活性明显下调,1个转座子显著上调;Cu^(2+)导致7个转座子上调,2个显著下调;Cd^(2+)导致6个转座子上调,3个显著下调。研究表明,斑马鱼转座子转录活性受环境因素影响显著,环境胁迫可能是转座子活性变化的原因之一。本研究对了解和评估环境因子对鱼类转座子活性的影响作用具有重要的意义,为进一步研究生物基因组的进化机制提供参考。

Transposons are movable and extended elements, they are important parts in genome and can affect the genome evolution. Transposable activity is usually regulated by environmental factors. To discuss the influence of environmental stress on the activity of transposons, the zebrafish embryos at early stage were exposed to TCDD,Cu2＋ and Cd2＋ for two hours, respectively. Then the embryos were cultured in normal medium until 72 hpf. The total RNA of embryos were extracted and transcribed into c DNA by reverse transcription. Then the transcription activity of 9 transposons with complete gene structures after exposure were compared with that before by real-time quantity fluorescent PCR. The 9 transposons included 5 DNA transposons（Tc-a, Tc-b, Tc-c, Tc-d and Tc-e） and 4 retrotransposons（ZB-ERV-1, ZB-ERV-2, 2 L1-323 and L1-21）. The results showed that the transcription activity of 8 transposons treated with TCDD obviously decreased, and that of one significantly increased; the transcription activity of 7 transposons treated with Cu2＋ obviously increased, and that of 2 were significantly decreased; the transcription activity of 6 transposons treated with Cd2＋ obviously increased, and that of 3 significantly decreased.Those results suggested that environment factors can significantly affect transposons expression activity, and environment stress could be the important reason for the variation of transposon activity. Those data play a very important role in evaluating and understanding the effect of environment factors on fish genome and transposon activity, and provide reference for further research on biology genome evolutionary mechanism.