Pimpinelli S, Dimitri P
Istituto di Genetica, Universita di Bari, Italy.
Genetics. 1989 Apr;121(4):765-72. doi: 10.1093/genetics/121.4.765.
The segregation distortion phenomenon occurs in Drosophila melanogaster males carrying an SD second chromosome and an SD+ homolog. In such males the SD chromosome is transmitted to the progeny more frequently than the expected 50% because of an abnormal differentiation of the SD+-bearing sperms. Three major loci are involved in this phenomenon: SD and Rsp, associated with the SD and SD+ chromosome, respectively, and E(SD). In the present work we performed a cytogenetic analysis of the Rsp locus which was known to map to the centromeric heterochromatin of the second chromosome. Hoechst- and N-banding techniques were used to characterize chromosomes carrying Responder insensitive (Rspi), Responder sensitive (Rsps) and Responder supersensitive (Rspss) alleles. Our results locate the Rsp locus to the h39 region of 2R heterochromatin. This region is a Hoechst-bright, N-banding negative heterochromatic block adjacent to the centromere. Quantitative variations of the h39 region were observed. The degree of sensitivity to Sd was found to be directly correlated with the physical size of that region, demonstrating that the Rsp locus is composed of repeated DNA.
在携带SD第二染色体和SD +同源染色体的黑腹果蝇雄性中会出现分离畸变现象。在这类雄性中，由于携带SD +的精子异常分化，SD染色体传递给后代的频率高于预期的50%。这一现象涉及三个主要基因座：SD和Rsp，分别与SD和SD +染色体相关，以及E(SD)。在本研究中，我们对Rsp基因座进行了细胞遗传学分析，已知该基因座定位于第二染色体的着丝粒异染色质上。使用Hoechst和N带技术来表征携带不敏感应答者（Rspi）、敏感应答者（Rsps）和超敏感应答者（Rspss）等位基因的染色体。我们的结果将Rsp基因座定位到2R异染色质的h39区域。该区域是一个Hoechst亮、N带阴性的异染色质块，毗邻着丝粒。观察到h39区域的数量变化。发现对Sd的敏感程度与该区域的物理大小直接相关，表明Rsp基因座由重复DNA组成。
