Suppression of transposable elements (TEs) is paramount to maintain genomic integrity and organismal fitness. In D. melanogaster, the flamenco locus is a master suppressor of TEs, preventing the mobilization of certain endogenous retrovirus-like TEs from somatic ovarian support cells to the germline. It is transcribed by Pol II as a long (100s of kb), single-stranded, primary transcript, and metabolized into ~24-32 nt Piwi-interacting RNAs (piRNAs) that target active TEs via antisense complementarity. flamenco is thought to operate as a trap, owing to its high content of recent horizontally transferred TEs that are enriched in antisense orientation. Using newly-generated long read genome data, which is critical for accurate assembly of repetitive sequences, we find that flamenco has undergone radical transformations in sequence content and even copy number across simulans clade Drosophilid species. Drosophila simulans flamenco has duplicated and diverged, and neither copy exhibits synteny with D. melanogaster beyond the core promoter. Moreover, flamenco organization is highly variable across D. simulans individuals. Next, we find that D. simulans and D. mauritiana flamenco display signatures of a dual-stranded cluster, with ping-pong signals in the testis and/or embryo. This is accompanied by increased copy numbers of germline TEs, consistent with these regions operating as functional dual-stranded clusters. Overall, the physical and functional diversity of flamenco orthologs is testament to the extremely dynamic consequences of TE arms races on genome organization, not only amongst highly related species, but even amongst individuals.

中文翻译：

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果蝇物种中弗拉门戈基因座的快速进化多样化。

转座元件 (TE) 的抑制对于维持基因组完整性和有机体适应性至关重要。在黑腹果蝇中，弗拉门戈基因座是 TE 的主要抑制因子，可防止某些内源性逆转录病毒样 TE 从体细胞卵巢支持细胞动员到种系。它被 Pol II 转录为长（数百 kb）单链初级转录物，并代谢为约 24-32 nt Piwi 相互作用 RNA (piRNA)，通过反义互补性靶向活性 TE。弗拉门戈被认为是一个陷阱，因为它含有大量的近期水平转移的 TE，这些 TE 富含反义方向。使用新生成的长读基因组数据（这对于重复序列的精确组装至关重要），我们发现弗拉门戈在序列内容甚至整个果蝇物种中的拷贝数上发生了根本性的转变。模拟弗拉门戈果蝇已经复制和分化，并且除了核心启动子之外，两个副本均未表现出与黑腹果蝇的同线性。此外，弗拉明戈舞的组织在不同的拟果蝇个体之间存在很大差异。接下来，我们发现 D. simulans 和 D. mauritiana Flamenco 显示出双链簇的特征，在睾丸和/或胚胎中具有乒乓信号。这伴随着种系 TE 拷贝数的增加，与这些区域作为功能性双链簇的作用一致。总体而言，弗拉门戈直系同源物的物理和功能多样性证明了 TE 军备竞赛对基因组组织的极其动态的影响，不仅在高度相关的物种之间，甚至在个体之间。