Transposable elements (TEs) are not randomly distributed in the genome. A genome-wide analysis of the D. melanogaster genome found that differences in TE density across 50 kb genomic regions was due both to transposition and duplication. At smaller genomic scales, promoter regions of hsp genes and the promoter region of CG18446 have been shown to accumulate TE insertions. In this work, we have further analyzed the promoter region of CG18446. We screened 218 strains collected in 15 natural populations, and we found that the CG18446 promoter region contains 20 independent roo insertions. Based on phylogenetic analysis, we suggest that the presence of multiple roo insertions in this region is likely to be the result of several bursts of transposition. Moreover, we found that the roo insertional cluster in the CG18446 promoter region is unique: no other promoter region in the genome contains a similar number of roo insertions. We found that, similar to hsp gene promoters, chromatin accessibility could be one of the factors explaining the recurrent insertions of roo elements in CG18446 promoter region.

中文翻译：

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果蝇中应激反应基因启动子区域内独特的roo插入簇。

转座因子（TEs）并非随机分布在基因组中。对黑腹果蝇的基因组进行全基因组分析发现，跨50 kb基因组区域的TE密度差异是由于转座和重复。在较小的基因组规模上，已显示hsp基因的启动子区域和CG18446的启动子区域会积累TE插入。在这项工作中，我们进一步分析了CG18446的启动子区域。我们筛选了15个自然种群中收集的218株，我们发现CG18446启动子区域包含20个独立的roo插入。基于系统发育分析，我们建议在该区域中多个roo插入的存在可能是几次转座突变的结果。此外，我们发现CG18446启动子区域中的roo插入簇是唯一的：基因组中没有其他启动子区域包含相似数量的roo插入。我们发现，与hsp基因启动子类似，染色质可及性可能是解释CG18446启动子区域中roo元素反复插入的因素之一。