Epigenetic modifications like DNA methylation can alter an organism’s phenotype without changing its DNA sequence. Exposure to environmental toxicants has the potential to change the resilience of aquatic species. However, little information is available on the dynamics of DNA methylation in fish gonadal tissues in response to organophosphates. In the present work, reduced-representation bisulfite sequencing was performed to identify DNA methylation patterns in the ovarian tissues of Anabas testudienus exposed to organophosphates, specifically monocrotophos (MCP). Through sequencing, an average of 41,087 methylated cytosine sites were identified and distributed in different parts of genes, i.e., in transcription start sites (TSS), promoters, exons, etc. A total of 1058 and 1329 differentially methylated regions (DMRs) were detected as hyper-methylated and hypo-methylated in ovarian tissues, respectively. Utilizing whole-genome data of the climbing perch, the DMRs, and their associated overlapping genes revealed a total of 22 genes within exons, 45 genes at transcription start sites (TSS), and 218 genes in intergenic regions. Through gene ontology analysis, a total of 16 GO terms particularly involved in ovarian follicular development, response to oxidative stress, oocyte maturation, and multicellular organismal response to stress associated with reproductive biology were identified. After functional enrichment analysis, relevant DMGs such as steroid hormone biosynthesis (Cyp19a, 11-beta-HSD, 17-beta-HSD), hormone receptors (ar, esrrga), steroid metabolism (StAR), progesterone-mediated oocyte maturation (igf1ar, pgr), associated with ovarian development in climbing perch showed significant differential methylation patterns. The differentially methylated genes (DMGs) were subjected to analysis using real-time PCR, which demonstrated altered gene expression levels. This study revealed a molecular-level alteration in genes associated with ovarian development in response to chemical exposure. This work provides evidence for understanding the relationship between DNA methylation and gene regulation in response to chemicals that affect the reproductive fitness of aquatic animals.

DNA 甲基化等表观遗传修饰可以改变生物体的表型，而不改变其 DNA 序列。接触环境毒物有可能改变水生物种的恢复能力。然而，关于鱼类性腺组织中 DNA 甲基化响应有机磷酸盐动态的信息很少。在目前的工作中，进行了简化代表性亚硫酸氢盐测序，以鉴定暴露于有机磷酸盐，特别是久效磷（MCP）的Anabas testudienus卵巢组织中的DNA甲基化模式。通过测序，平均鉴定出41,087个甲基化胞嘧啶位点，分布在基因的不同部位，即转录起始位点（TSS）、启动子、外显子等。总共检测到1058个和1329个差异甲基化区域（DMR）分别为卵巢组织中的高甲基化和低甲基化。利用攀缘鲈的全基因组数据、DMR 及其相关重叠基因，揭示了外显子内总共有 22 个基因、转录起始位点 (TSS) 上的 45 个基因以及基因间区域中的 218 个基因。通过基因本体分析，总共鉴定了 16 个 GO 术语，特别涉及卵巢卵泡发育、氧化应激反应、卵母细胞成熟以及与生殖生物学相关的多细胞生物体应激反应。经过功能富集分析后，相关DMG如类固醇激素生物合成（Cyp19a、11-β-HSD、17-β-HSD）、激素受体（ar、esrrga）、类固醇代谢（StAR）、黄体酮介导的卵母细胞成熟（igf1ar、pgr）与攀鲈卵巢发育相关，表现出显着差异的甲基化模式。使用实时 PCR 对差异甲基化基因 (DMG) 进行分析，结果表明基因表达水平发生了改变。这项研究揭示了与卵巢发育相关的基因因化学暴露而发生分子水平的改变。这项工作为理解 DNA 甲基化和基因调控之间的关系提供了证据，以响应影响水生动物生殖健康的化学物质。