Epigenetic silencing of a foreign gene in nuclear transformants of Chlamydomonas
Epigenetic silencing of a foreign gene in nuclear transformants of Chlamydomonas
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DOI：
10.1105/tpc.9.6.925
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发表时间：
1997-06-01
期刊：
影响因子：
11.6
通讯作者：
Boynton, JE
中科院分区：
文献类型：
--
作者：
Cerutti, H;Johnson, AM;Boynton, JE
外源基因的不稳定表达是转基因技术在植物中应用的一个严重问题。在单细胞绿色莱茵衣藻的转化体中，赋予壮观霉素抗性的真细菌aadA基因的表达被可逆的表观遗传机制转录抑制。在不同浓度的壮观霉素上存活的集落的大小和频率的变化以及引入的转基因的转录活性水平表明在遗传上相同的细胞中存在中间表达状态。基因沉默与整合的DNA的甲基化无关，并且不涉及其染色质结构的大的改变，如用限制性内切酶和DNA酶I消化所显示的。转基因抑制通过较低的温度增强，类似于果蝇中的位置效应杂色。通过类比几种真核生物中的表观遗传现象，我们的研究结果表明（异）染色质染色体结构域在转录失活中可能发挥作用。
The unstable expression of introduced genes poses a serious problem for the application of transgenic technology in plants. In transformants of the unicellular green alga Chlamydomonas reinhardtii, expression of a eubacterial aadA gene, conferring spectinomycin resistance, is transcriptionally suppressed by a reversible epigenetic mechanism(s). Variations in the size and frequency of colonies surviving on different concentrations of spectinomycin as well as the levels of transcriptional activity of the introduced transgene(s) suggest the existence of intermediate expression states in genetically identical cells, Gene silencing does not correlate with methylation of the integrated DNA and does not involve large alterations in its chromatin structure, as revealed by digestion with restriction endonucleases and DNase I. Transgene repression is enhanced by lower temperatures, similar to position effect variegation in Drosophila. By analogy to epigenetic phenomena in several eukaryotes, our results suggest a possible role for (hetero)chromatic chromosomal domains in transcriptional inactivation.