Engels W R, Preston C R
Cell. 1981 Nov;26(3 Pt 1):421-8. doi: 10.1016/0092-8674(81)90211-7.
A syndrome of germline abnormalities in Drosophila melanogaster called hybrid dysgenesis is thought to be caused by transposable genetic elements known as P factors. Several lines of evidence presented here show that the chromosomal positions of at least some P factors can be identified as points of frequent chromosome breakage (hotspots). Starting with a strain (pi 2) in which four hotspots had been identified on the X chromosome, we found individual hotspots vanished when their part of the chromosome was replaced by the homologous part from a strain known to lack P factors. All hotspots in the non-substituted parts of the chromosome remained functional, indicating that they can act autonomously. We also observed a new breakage site coinciding with the appearance of an unstable mutation at the singed bristle locus (snW). This mutation was dysgenesis-induced, and previous genetic evidence suggested that it was caused by the insertion of a P factor at that locus. We also present preliminary evidence for rapid scrambling of the positions of hotspots under certain conditions, and we describe a new procedure for efficiently determining the positions of hotspots on a given chromosome.
果蝇中一种称为杂种不育的种系异常综合征被认为是由称为P因子的转座遗传元件引起的。本文提供的几条证据表明，至少一些P因子的染色体位置可被确定为频繁染色体断裂点（热点）。从一个在X染色体上已鉴定出四个热点的品系（pi 2）开始，我们发现当染色体的一部分被已知缺乏P因子的品系的同源部分取代时，个别热点消失了。染色体未被取代部分的所有热点仍然起作用，这表明它们可以自主发挥作用。我们还观察到一个新的断裂位点，它与刚毛位点（snW）处不稳定突变的出现相吻合。这个突变是由杂种不育诱导的，先前的遗传证据表明它是由该位点插入一个P因子引起的。我们还提供了在某些条件下热点位置快速重排的初步证据，并描述了一种有效确定给定染色体上热点位置的新方法。
