Rushlow C A, Bender W, Chovnick A
Genetics. 1984 Nov;108(3):603-15. doi: 10.1093/genetics/108.3.603.
Experiments are described that extend the characterization of position effect variants of the rosy locus and test possible mechanisms of heterochromatic position effect. Rosy position effect variants exhibit a variegated phenotype with respect to xanthine dehydrogenase activity in malpighian tubules. The breakpoints of the position effect mutations are located on the DNA map of the rosy region outside of the rosy locus DNA; ryps11136 is located in the DNA of the l(3)S12 gene immediately proximal to rosy, whereas ryps1149 is located some 15 kb distal to rosy in the pic locus. Southern blot experiments are described that test and reject the notion that heterochromatic position effect results from underreplication of the position-affected gene. Rather, the results of Northern blots serve to direct attention to position effect as a defect in transcription. Histone region deletion heterozygosity and butyrate-feeding experiments failed to exhibit specific suppression of position effect at the rosy locus.
本文描述了一些实验，这些实验扩展了对朱红基因座位置效应变体的特征描述，并测试了异染色质位置效应的可能机制。朱红位置效应变体在马尔皮基氏管中黄嘌呤脱氢酶活性方面表现出斑驳的表型。位置效应突变的断点位于朱红基因座DNA之外的朱红区域的DNA图谱上；ryps11136位于紧邻朱红的l(3)S12基因的DNA中，而ryps1149位于朱红下游约15 kb处的pic基因座中。文中描述了Southern印迹实验，这些实验测试并否定了异染色质位置效应是由位置受影响基因的复制不足导致的这一观点。相反，Northern印迹的结果将注意力引向位置效应是一种转录缺陷。组蛋白区域缺失杂合性和丁酸盐喂养实验未能在朱红基因座处表现出对位置效应的特异性抑制。
