The use of anticancer drugs in chemotherapy is increasing, leading to growing environmental concentrations of imatinib mesylate (IMA), cisplatinum (CDDP), and etoposide (ETP) in aquatic systems. Previous studies have shown that these anticancer drugs cause DNA damage in the crustacean Daphnia magna at low, environmentally relevant concentrations. To explore the mechanism of action of these compounds and the downstream effects of DNA damage on D. magna growth and development at a sensitive life stage, we exposed neonates to low level concentrations equivalent to those that elicit DNA damage (IMA: 2000 ng/L, ETP: 300 ng/L, CDDP: 10 ng/L) and performed transcriptomic analysis using an RNA-seq approach. RNA sequencing generated 14 million reads per sample, which were aligned to the D. magna genome and assembled, producing approximately 23,000 transcripts per sample. Over 90% of the transcripts showed homology to proteins in GenBank, revealing a high quality transcriptome assembly, although functional annotation was much lower. RT-qPCR was used to identify robust biomarkers and confirmed the downregulation of an angiotensin converting enzyme-like gene (ance) involved in neuropeptide regulation across all three anticancer drugs and the down-regulation of DNA topoisomerase II by ETP. RNA-seq analysis also allowed for an in depth exploration of the differential splicing of transcripts revealing that regulation of different gene isoforms predicts potential impacts on translation and protein expression, providing a more meaningful assessment of transcriptomic data. Enrichment analysis and investigation of affected biological processes suggested that the DNA damage caused by ETP and IMA influences cell cycle regulation and GPCR signaling. This dysregulation is likely responsible for effects to neurological system processes and development, and overall growth and development. Our transcriptomic approach provided insight into the mechanisms that respond to DNA damage caused by anticancer drug exposure and generated novel hypotheses on how these chemicals may impact the growth and survival of this ecologically important zooplankton species.

抗癌药物在化学疗法中的使用正在增加，导致水生系统中甲磺酸伊马替尼（IMA），顺铂（CDDP）和依托泊苷（ETP）的环境浓度不断增加。先前的研究表明，这些抗癌药物在低的，与环境有关的浓度下会导致甲壳类水蚤的DNA损伤。为了探索这些化合物的作用机理以及DNA损伤在敏感生命阶段对大果蝇生长和发育的下游影响，我们将新生儿暴露在与引起DNA损伤的浓度相当的低浓度浓度下（IMA：2000 ng / L ，ETP：300 ng / L，CDDP：10 ng / L），并使用RNA-seq方法进行转录组分析。RNA测序每个样品产生了1400万个读数，这些读数与D. magna基因组并组装，每个样品产生大约23,000个转录本。超过90％的转录本显示出与GenBank中蛋白质的同源性，揭示了高质量的转录组装配，尽管功能注释要低得多。RT-qPCR的用于鉴定生物标记健壮并确认血管紧张素转换酶样基因（下调ANCE）参与了所有三种抗癌药物的神经肽调节以及ETP对DNA拓扑异构酶II的下调。RNA-seq分析还允许对转录物的差异剪接进行深入探索，揭示出对不同基因同工型的调控可预测对翻译和蛋白质表达的潜在影响，从而提供更有意义的转录组数据评估。富集分析和受影响的生物过程的研究表明，由ETP和IMA引起的DNA损伤影响细胞周期调控和GPCR信号传导。这种失调可能是对神经系统过程和发育以及总体生长和发育的影响。