Engels W R, Johnson-Schlitz D M, Eggleston W B, Sved J
Genetics Department, University of Wisconsin, Madison 53706.
Cell. 1990 Aug 10;62(3):515-25. doi: 10.1016/0092-8674(90)90016-8.
P transposable elements in Drosophila melanogaster can undergo precise loss at a rate exceeding 13% per generation. The process is similar to gene conversion in its requirement for a homolog that is wild type at the insertion site and in its reduced frequency when pairing between the homologs is inhibited. However, it differs from classical gene conversion by its high frequency, its requirement for P transposase, its unidirectionality, and its occurrence in somatic and premeiotic cells. Our results suggest a model of P element transposition in which jumps occur by a "cut-and-paste" mechanism but are followed by double-strand gap repair to restore the P element at the donor site. The results also suggest a technique for site-directed mutagenesis in Drosophila.
黑腹果蝇中的P转座因子每代能以超过13%的速率精确缺失。该过程在要求插入位点处为野生型的同源物以及在同源物配对受抑制时频率降低方面类似于基因转换。然而，它与经典基因转换不同，体现在其高频性、对P转座酶的需求、单向性以及在体细胞和减数分裂前细胞中的发生情况。我们的结果提出了一种P元件转座模型，其中跳跃通过“剪切粘贴”机制发生，但随后通过双链缺口修复在供体位点恢复P元件。结果还提出了一种在果蝇中进行定点诱变的技术。
