Mobilization of two retroelements, ZAM and Idefix, in a novel unstable line of Drosophila melanogaster
Mobilization of two retroelements, ZAM and Idefix, in a novel unstable line of Drosophila melanogaster
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DOI：
10.1093/oxfordjournals.molbev.a026038
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发表时间：
1999-01-01
影响因子：
10.7
通讯作者：
Vaury, C
中科院分区：
文献类型：
--
作者：
Desset, S;Conte, C;Vaury, C
我们描述了黑腹果蝇品系 RevI 中的一种新型转座系统，其中两种逆转录因子被动员。这些元素是最近在文献中描述的逆向元素 ZAM，以及名为 Idefix 的新颖元素。与 ZAM 一样，Idefix 显示了脊椎动物逆转录病毒的结构特征。它的三个开放阅读框编码的预测产物类似于逆转录病毒的 gag、pol 和 env 基因的产物。对 RevI 基因组进行的原位杂交和 Southern 分析显示，在原始亲本系的染色体臂上存在约 20 个拷贝的 ZAM 和 Idefix，而 ZAM 不存在，而 Idefix 仅存在于 4 个拷贝中。从 RevI 中，已经恢复了一系列影响眼睛颜色的突变。对这些突变的遗传和分子分析表明，大多数突变通过三轮突变事件影响白色基因座。先前表明第一个突变事件是由白色转录起始位点上游 3lib 处的 ZAM 插入引起的。它赋予亲本系的橙色眼睛颜色以红砖表型。第二个事件是由于在白色基因转录起始位点上游 1.7 kb 处插入 Idefix 拷贝导致的，它将红砖表型修改为橙色。第二次突变事件在 11 个独立个体中作为反复出现的特定突变而被恢复。第三个事件是由位于白色上游 1.7 kb 的额外 Idefix 引起的，该 Idefix 负责将橙色表型完全逆转为红砖色。事实上，由于 ZAM 和 Idefix 在白色基因座上反复出现而导致的突变导致了如此多种表型，这一事实揭示了一个新的分子系统，在该系统中可以测试移动元件对宿主基因正确表达的干扰。
We describe a novel transposition system in a line of Drosophila melanogaster called RevI in which two retroelements are mobilized. These elements are the retroelement ZAM, recently described in the literature, and a novel element designated Idefix. Like ZAM, Idefix displays the structural features of a vertebrate retrovirus. Its three open reading frames encode predicted products resembling the products of the gag, pol, and env genes of retroviruses. In situ hybridization and Southern analyses performed on the RevI genome revealed the presence of some 20 copies of ZAM and Idefix, whereas ZAM is absent and Idefix is present in only four copies on the chromosomal arms of the original parental line. From RevI, a series of mutations affecting eye coloration has been recovered. The genetic and molecular analyses of these mutations have shown that most of them affected the white locus through three rounds of mutational events. The first mutational event was previously shown to be caused by a ZAM insertion 3 lib upstream of the transcription start site of white. It confers a red-brick phenotype to the orange eye coloration of the parental line. The second event results from the insertion of an Idefix copy 1.7 kb upstream of the transcription start site of the white gene, which modifies the red-brick phenotype to orange. This second mutational event was recovered as a recurrent specific mutation in 11 independent individuals. The third event results from an additional Idefix located 1.7 kb upstream of white that is responsible for the full reversion of the orange phenotype to redbrick. The fact that such mutations due to recurrent appearances of both ZAM and Idefix at the white locus result in such a variety of phenotypes brings to light a new molecular system in which the interference of mobile elements with the correct expression of the host gene can be tested.