Raw data values from all experiments.

Accurate repair of DNA double-strand breaks (DSBs) is essential for the maintenance of genome integrity, as failure to repair DSBs can result in cell death. The cell has evolved two main mechanisms for DSB repair: non-homologous end-joining (NHEJ) and homology-directed repair (HDR), which includes single-strand annealing (SSA) and homologous recombination (HR). While certain factors like age and state of the chromatin are known to influence DSB repair pathway choice, the roles of developmental stage, tissue type, and sex have yet to be elucidated in multicellular organisms. To examine the influence of these factors, DSB repair in various embryonic developmental stages, larva, and adult tissues in Drosophila melanogaster was analyzed through molecular analysis of the DR-white assay using Tracking across Indels by DEcomposition (TIDE). The proportion of HR repair was highest in tissues that maintain the canonical (G1/S/G2/M) cell cycle and suppressed in both terminally differentiated and polyploid tissues. To determine the impact of sex on repair pathway choice, repair in different tissues in both males and females was analyzed. When molecularly examining tissues containing mostly somatic cells, males and females demonstrated similar proportions of HR and NHEJ. However, when DSB repair was analyzed in male and female premeiotic germline cells utilizing phenotypic analysis of the DR-white assay, there was a significant decrease in HR in females compared to males. This study describes the impact of development, tissue-specific cycling profile, and, in some cases, sex on DSB repair outcomes, underscoring the complexity of repair in multicellular organisms.

DNA双链断裂（double-strand breaks, DSBs）的精准修复对于维持基因组完整性至关重要，若无法修复DSBs则会引发细胞死亡。细胞演化出两种主要的DSBs修复机制：非同源末端连接（non-homologous end-joining, NHEJ）与同源定向修复（homology-directed repair, HDR），后者涵盖单链退火（single-strand annealing, SSA）与同源重组（homologous recombination, HR）。尽管已知年龄与染色质状态等因素会影响DSBs修复通路的选择，但在多细胞生物中，发育阶段、组织类型以及性别所发挥的作用仍有待阐明。为探究上述因素的影响，本研究以黑腹果蝇（Drosophila melanogaster）为对象，借助基于分解识别插入缺失的追踪技术（Tracking across Indels by DEcomposition, TIDE）开展DR-white检测的分子分析，对其不同胚胎发育阶段、幼虫及成体组织内的DSBs修复情况进行了检测。HR修复占比在维持典型细胞周期（G1/S/G2/M）的组织中最高，而在终末分化组织与多倍体组织中均受到抑制。为明确性别对修复通路选择的影响，本研究对雌雄个体不同组织的修复情况展开了分析。在对以体细胞为主的组织进行分子检测时，雌雄个体的HR与NHEJ占比并无显著差异。但借助DR-white检测的表型分析，对雌雄个体减数分裂前生殖细胞的DSBs修复情况进行检测时，雌性个体的HR占比显著低于雄性。本研究阐明了发育进程、组织特异性细胞周期特征，以及部分场景下性别对DSBs修复结局的影响，凸显了多细胞生物修复机制的复杂性。