Engels W R
Science. 1984 Dec 7;226(4679):1194-6. doi: 10.1126/science.6095450.
A transposable genetic element of the P family in Drosophila melanogaster was found to be unstable in the presence of other P elements but stable in their absence. A sensitive assay for P transpositional activity is provided by the snw allele, a defective P insert in the singed bristle locus which becomes hypermutable only in the presence of complete elements. This measure of activity was highly correlated with a type of female sterility normally associated with P activity. There was no cross-reactivity with transposase from another hybrid dysgenesis-causing element (the I factor).
在果蝇中发现，P家族的一种转座遗传元件在存在其他P元件时不稳定，但在不存在其他P元件时稳定。snw等位基因提供了一种检测P转座活性的灵敏方法，snw等位基因是位于焦刚毛基因座上的一个有缺陷的P插入片段，它只有在存在完整元件时才会发生高频突变。这种活性测量与通常与P活性相关的一种雌性不育类型高度相关。它与另一种导致杂种不育的元件（I因子）的转座酶没有交叉反应。
