这篇文章出现一个新名词:the developmental relaxation of transposable element silencing (DRTS)。这个词的中文翻译好像有点扯,所以就不翻译了。意思大概是:在正常发育过程中转座元件表达。有什么功能呢?文章推测:One function may be the production of transposable element small RNAs.产生小RNA。小RNA是一种重要的基因表达调控因子。当然在此基础上可以合理的推测:不同的转座子会产生不同的小RNA,用来调控不同的基因表达。如果用已知的小RNA数据库和已知的转座子数据库去进行序列比对,也许能够建立小RNA和具体的转座子间的联系。
结论:The epigenetic interplay between TE and genes thus plays a crucial role in the TE-host co-evolution.TE和基因的表观遗传学互作在转座子-宿主基因组的共同进化中扮演关键较色。换句话说:转座子通过表观遗传学机制发生作用。
本文亮点:
A TE transcription is massively released in Arabidopsis epigenetic mutants and under stress conditions.在拟南芥的表观遗传学突变体和逆境条件下发生大量的TE转录(拟南芥是这样,那么水稻、玉米等估计也8 9不离10)。 B► TE transposition across generations is limited to a few TE families as revealed in Arabidopsis epigenetic mutants after inbreeding. 要理解这点得看下全文 C► TE neo-insertions can attract epigenetic marks to nearby genes thereby modifying the host gene expression.TE的插入为旁侧基因引入表观遗传学标记,从而影响基因表达。
小结1 2:1 是说TE的表达会有功能 2 是说TE的转座会有功能。共同点:影响基因表达调控。
3 Transcriptional Silencing of Transposons by Piwi and Maelstrom and Its Impact on Chromatin State and Gene Expression(http://www.sciencedirect.com/science/article/pii/S0092867412013037).这篇文章研究了转座子沉默的分子机制。所以人家发CELL了。进行转座子的研究可以发CELL,这对中国科学家有积极的意义。根据这篇文章的信息在动物的性腺存在一条转座沉默调控途径:The piRNA pathway。文章结论:Our work illustrates the widespread influence of transposons and the piRNA pathway on chromatin patterns and gene expression.转座子和piRNA途径广泛影响染色质结构和基因表达。由此看,转座子不但有功能,而且是非常重要的功能。问题自然就来了,植物组织中是否有类似的调控途径和相似的功能?既然有抑制的途径,那很自然地有促进途径,这个途径是什么?调控的关键节点在哪?如果能人为控制这个开关。。。?当这么重要的东西,曾今被认为是“垃圾DNA”,如果现在还固执的这么认为,那么是不是应该反问下:“我是不是垃圾?”了。在这个具体问题上,我不是垃圾。
4 Transposable Elements: An Abundant and Natural Source of Regulatory Sequences for Host Genes(http://www.annualreviews.org/doi/abs/10.1146/annurev-genet-110711-155621)这是2012年的一篇关注转座子的重量级文章。摘要如下:The fact that transposable elements (TEs) can influence host gene expression was first recognized more than 50 years ago. However, since that time, TEs have been widely regarded as harmful genetic parasites—selfish elements that are rarely co-opted by the genome to serve a beneficial role. Here, we survey recent findings that relate to TE impact on host genes and remind the reader that TEs, in contrast to other noncoding parts of the genome, are uniquely suited to gene regulatory functions. We review recent studies that demonstrate the role of TEs in establishing and rewiring gene regulatory networks and discuss the overall ubiquity of exaptation. We suggest that although individuals within a population can be harmed by the deleterious effects of new TE insertions, the presence of TE sequences in a genome is of overall benefit to the population.