Levy A A, Walbot V
Department of Biological Sciences, Stanford University, CA 94305-5020.
Science. 1990 Jun 22;248(4962):1534-7. doi: 10.1126/science.2163107.
The ability of transposable elements (TEs) to insert into or excise out of a genetic locus can be regulated by genetic, environmental, and developmental factors. Tissue- or organ-specific activity of TEs is a frequent and well-characterized example of spatial, developmental regulation. Regulation of the timing of TE activity during ontogeny is less well understood. To analyze timing, TE-induced variegation was quantified in the aleurone of maize kernels, a tissue composed of only a single layer of cells, and sector sizes were assigned to specific cell divisions in aleurone development. Three TE families, Mu, Spm, and Ac/Ds, were studied at two genetic loci. It was found that the frequency of transposon excision changes drastically (up to 30-fold increase or equivalent decrease) during the proliferation of the aleurone. Moreover, these changes occur at the same cell divisions in all three TE families. These results suggest that the timing of TE excision during maize development can be controlled by the host.
转座元件（TEs）插入或切除基因位点的能力可受到遗传、环境和发育因素的调控。TEs的组织或器官特异性活性是空间发育调控中常见且特征明确的例子。在个体发育过程中，TE活性时间的调控则了解较少。为了分析时间调控，对玉米籽粒糊粉层（仅由单层细胞组成的组织）中TE诱导的斑驳进行了定量，并将扇区大小与糊粉层发育中的特定细胞分裂相关联。在两个基因位点研究了三个TE家族，即Mu、Spm和Ac/Ds。结果发现，在糊粉层增殖过程中，转座子切除频率急剧变化（增加多达30倍或同等程度的降低）。此外，所有三个TE家族的这些变化都发生在相同的细胞分裂阶段。这些结果表明，玉米发育过程中转座子切除的时间可由宿主控制。
