Pollution is a major global concern affecting biodiversity, particularly of freshwater species. Populations have developed mechanisms to deal with pollution, such as the chemical defensome, which is a set of genes involved in maintaining internal stability. Pollution significantly affects the Maipo River basin in Chile. This area is home to the endemic silverside fish Basilichthys microlepidotus, whose populations are affected by pollution to different degrees. We assessed gene expression in the liver and gill of this species, focusing on whole-transcriptome and chemical-defensome levels, to identify both independent and shared mechanisms in response to pollution. The results showed that 14–18 genes were consistently expressed differently among populations in polluted areas. These genes were primarily involved in liver cell mitosis and in responses to organic chemicals and carcinogenic processes. Genes expressed differently in the gill were more abundant in immune system biological processes. All populations consistently downregulated chemical-defensome genes in the liver. In differentially expressed chemical-defensome genes, shared biological processes included virus response, cellular redox homeostasis and transport, organic cyclic compound response and DNA-templated transcription regulation. Studying chemical-defensome genes can help reveal common ways that pollution builds up over time, and examining the whole transcriptome can elucidate the context in which this response develops.

中文翻译：

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智利中部迈坡河流域银边鱼 Basilichthys microlepidotus 响应慢性污染的化学防御性和全转录组表达


污染是影响生物多样性，尤其是淡水物种的生物多样性的主要全球问题。种群已经开发出处理污染的机制，例如化学防御体，这是一组参与维持内部稳定的基因。污染严重影响智利的迈坡河流域。该地区是特有银边鱼 Basilichthys microlepidotus 的家园，其种群受到不同程度的污染影响。我们评估了该物种肝脏和鳃中的基因表达，重点关注全转录组和化学防御水平，以确定响应污染的独立和共享机制。结果表明，14-18 个基因在污染地区的种群中始终以不同的方式表达。这些基因主要参与肝细胞有丝分裂以及对有机化学物质和致癌过程的反应。在鳃中表达不同的基因在免疫系统生物过程中更为丰富。所有种群都一致下调肝脏中的化学防御基因。在差异表达的化学防御体基因中，共享的生物过程包括病毒反应、细胞氧化还原稳态和转运、有机环化合物反应和 DNA 模板转录调控。研究化学防御性基因有助于揭示污染随着时间的推移而积累的常见方式，而检查整个转录组可以阐明这种反应发展的背景。