Department of Biology, Stanford University Stanford, CA, USA.
Front Plant Sci. 2012 Sep 13;3:212. doi: 10.3389/fpls.2012.00212. eCollection 2012.
Mu killer contains a partial inverted duplication of the mudrA transposase gene and two copies of the terminal inverted repeat A (TIRA) region of the master MuDR element of maize. Mu killer can effectively silence single copy MuDR/Mu lines, and it is proposed that a ∼4 kb hairpin RNA is generated by read through transcription from a flanking gene and that this transcript serves as a substrate for siRNA production. Mu killer was sequenced, except for a recalcitrant portion in the center of the locus, and shown to be co-linear with mudrA as originally proposed. The ability of the dominant Mu killer locus to silence a standard high copy number MuDR/Mu transposon line was evaluated. After two generations of exposure, about three quarters of individuals were silenced indicating reasonable effectiveness as measured by the absence of mudrA transposase transcripts. Mu killer individuals that effectively silenced MuDR expressed two short antisense transcripts. In contrast, Mu killer individuals that failed to silence MuDR expressed multiple sense transcripts, derived from read through transcription initiating in a flanking gene, but no antisense transcripts were detected.
Mu 杀手含有玉米 MuDR 主元件末端反向重复 A（TIRA）区域的两个拷贝和 mudrA 转座酶基因的部分反向重复。Mu 杀手可以有效地沉默单拷贝 MuDR/Mu 系，据推测，一个约 4kb 的发夹 RNA 是由侧翼基因的通读转录产生的，该转录物作为 siRNA 产生的底物。Mu 杀手进行了测序，除了位于基因座中心的一个顽固部分外，与最初提出的 mudrA 共线性。显性 Mu 杀手基因座沉默标准高拷贝数 MuDR/Mu 转座子系的能力进行了评估。经过两代暴露，大约四分之三的个体被沉默，表明沉默效果合理，因为没有检测到 mudrA 转座酶转录本。有效沉默 MuDR 的 Mu 杀手个体表达了两个短的反义转录本。相比之下，未能沉默 MuDR 的 Mu 杀手个体表达了多个正义转录本，这些转录本来源于侧翼基因起始的通读转录，但未检测到反义转录本。
