ABSTRACT

Norethisterone (NET) is one of the earliest synthetic progestins. Its widespread and long-term use means that NET is often detected on the surface and in groundwater samples, which may cause harm to aquatic organisms. Marine medaka (Oryzias melastigma) is a brackish fish, often used in ecotoxicology studies. In this study, the effect of norethisterone exposure on the transcriptome of marine medaka larvae was analyzed. Larvae were exposed to 10 ng/L NET for 24 h, then RNA-Seq was performed. Exposure to 10 ng/L NET resulted in 306 up-regulated and 516 down-regulated genes. An enrichment analysis revealed that differentially expressed genes (DEGs) were significantly enriched in metabolic and biosynthetic pathways, including DNA replication, proteasome, steroid biosynthesis, and other amino acid metabolism pathways. In the DNA replication pathway, all the DEGs were down-regulated, while in the steroid biosynthesis pathway, sqle, hmgcr, dhcr7, and dhcr24 were down-regulated. Quantitative real-time PCR (qPCR) was used to verify 12 DEGs, confirming that the validity of the RNA-Seq analysis. These results show that even low environmental concentrations of NET can lead to transcription level changes of genes related to fish growth and development, which may have adverse effects on the early development and growth of aquatic organisms.

Highlights

1. Transcriptomes from norethisterone-exposed marine medaka larvae were obtained

2. A total of 822 differentially expressed genes were identified

3. Norethisterone affected 155 pathways, including DNA replication.

摘要

炔诺酮 (NET) 是最早的合成孕激素之一。其广泛和长期使用意味着 NET 经常在地表和地下水样本中被检测到，这可能会对水生生物造成危害。海洋青鳉（Oryzias melastigma) 是一种微咸鱼，常用于生态毒理学研究。在这项研究中，分析了炔诺酮暴露对海洋青鳉幼虫转录组的影响。幼虫暴露于 10 ng/L NET 24 小时，然后进行 RNA-Seq。暴露于 10 ng/L NET 导致 306 个上调基因和 516 个下调基因。富集分析显示差异表达基因 (DEG) 在代谢和生物合成途径中显着富集，包括 DNA 复制、蛋白酶体、类固醇生物合成和其他氨基酸代谢途径。在 DNA 复制途径中，所有 DEGs 都被下调，而在类固醇生物合成途径中，sqle、hmgcr、dhcr 7 和dhcr24 个被下调。定量实时 PCR (qPCR) 用于验证 12 个 DEG，确认 RNA-Seq 分析的有效性。这些结果表明，即使环境浓度较低的 NET 也会导致与鱼类生长发育相关的基因转录水平发生变化，这可能对水生生物的早期发育和生长产生不利影响。

强调

1. 获得了暴露于炔诺酮的海洋青鳉幼虫的转录组

2. 共鉴定出822个差异表达基因

3. 炔诺酮影响 155 条通路，包括 DNA 复制。