转位因子（transposable elements，TEs）在植物和动物的基因组中到处存在，但是科学家还不是很清楚基因组如何适应成百甚至数千新的转位因子的快速插入。
在最近的一项研究中，乔治亚大学的植物生物学家首次证实这些突然的插入对水稻的影响。
这项研究一惊奇的发现是：转位因子对宿主的影响似乎是中性的。此外，研究人员表示，遗传多样性，是由大量TE的快速插入造成的。这种意想不到的方式实际上对植物来说是有益的。
这项发现是全新的，也确实是很让人兴奋的。该研究的负责人Susan Wessler介绍说，他们所研究的TE避开了在外显子区域的插入。但是更重要的一点是，像水稻这类自我授粉的植物，TE的闯入可能是它们在面对不断变化的环境，一种快速产生遗传多样性的重要方式。
这项研究结果发布在Nature的在线版本上。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 461, 1130-1134 (22 October 2009) | doi:10.1038/nature08479
Unexpected consequences of a sudden and massive transposon amplification on rice gene expression
Ken Naito1,2, Feng Zhang1,3, Takuji Tsukiyama2, Hiroki Saito2, C. Nathan Hancock1, Aaron O. Richardson1, Yutaka Okumoto2, Takatoshi Tanisaka2 & Susan R. Wessler1
1.Department of Plant Biology, University of Georgia, Athens, Georgia 30602, USA
2.Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
3.Present address: Department of Genetics, Cell Biology and Development, University of Minnesota, Minnesota 55455, USA.
Correspondence to: Takatoshi Tanisaka2Susan R. Wessler1 Correspondence and requests for materials should be addressed to S.R.W. or T.Tanisaka.
High-copy-number transposable elements comprise the majority of eukaryotic genomes where they are major contributors to gene and genome evolution1. However, it remains unclear how a host genome can survive a rapid burst of hundreds or thousands of insertions because such bursts are exceedingly rare in nature and therefore difficult to observe in real time2. In a previous study we reported that in a few rice strains the DNA transposon mPing was increasing its copy number by 40 per plant per generation3. Here we exploit the completely sequenced rice genome to determine 1,664 insertion sites using high-throughput sequencing of 24 individual rice plants and assess the impact of insertion on the expression of 710 genes by comparative microarray analysis. We find that the vast majority of transposable element insertions either upregulate or have no detectable effect on gene transcription. This modest impact reflects a surprising avoidance of exon insertions by mPing and a preference for insertion into 5' flanking sequences of genes. Furthermore, we document the generation of new regulatory networks by a subset of mPing insertions that render adjacent genes stress inducible. As such, this study provides evidence for models first proposed previously4, 5, 6 for the involvement of transposable elements and other repetitive sequences in genome restructuring and gene regulation.
