Segregation distortion refers to an unusual genetic phenomenon in diploid organisms by which the two alleles at a locus in a parent are not recovered in the classical 1:1 Mendelian ratio in its offspring. The Drosophila melanogaster neogene Sd was created by a duplication breakpoint on the left arm of chromosome 2 (2L), and encodes a truncated RanGAP protein with normal GTPase activity but which mis-localizes to the nucleus and disrupts Ran gradients. Male flies carrying Sd exhibit segregation distortion for the Rsp locus on the right arm of chromosome 2 (2R). Specifically, spermatids inheriting chromosome 2 with the Sd + Rsp s(s) genotype, in heterozygous males of genotype Sd Rsp i / Sd + Rsp s(s) , fail to develop properly so that the majority of progeny (approaching 100%) carry just the Sd Rsp i chromosome. One recent paper reported novel RNAi-expressing transgenes with Sd -mimicking properties; and another reported localization of an X-linked suppressor which restores Mendelian transmission. This article highlights how Drosophila genetics resources made this possible, and the significance of these findings to nucleus-cytoplasm transactions of interest to the wider cell biology community.

中文翻译：

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斗鸡眼遗传学家的观点 VI. 黑腹果蝇的分离失真：解决“深奥难题”的最新进展

分离畸变是指二倍体生物中的一种不寻常的遗传现象，通过这种现象，在其后代中无法以经典的 1:1 孟德尔比例恢复亲本基因座上的两个等位基因。黑腹果蝇新基因 Sd 是由 2 号染色体 (2L) 左臂上的重复断点创建的，编码一个截断的 RanGAP 蛋白，具有正常的 GTPase 活性，但它错误地定位到细胞核并破坏了 Ran 梯度。携带 Sd 的雄性果蝇表现出染色体 2 (2R) 右臂 Rsp 基因座的分离失真。具体而言，在基因型为 Sd Rsp i / Sd + Rsp s(s) 的杂合雄性中，继承具有 Sd + Rsp s(s) 基因型的染色体 2 的精子细胞无法正常发育，因此大多数后代（接近 100%）携带只是 Sd Rsp i 染色体。最近的一篇论文报道了具有 Sd 模拟特性的新型 RNAi 表达转基因；和另一个报告的 X 连锁抑制器的定位，它可以恢复孟德尔传输。本文重点介绍了果蝇遗传学资源如何使这成为可能，以及这些发现对更广泛的细胞生物学界感兴趣的细胞核 - 细胞质交易的重要性。