Investigation of ammonia-induced lethal toxicity toward ion regulation in zebrafish embryos

Li Yih Lin, Chieh An Cheng, Sian Tai Liu, Jiun Lin Horng*


研究成果: 雜誌貢獻期刊論文同行評審


Ammonia is an environmental pollutant that is toxic to all aquatic animals. However, the mechanism of ammonia toxicity toward the ion regulatory function of early-stage fish has not been fully documented. We addressed this issue using zebrafish embryos as a model. We hypothesized that ammonia might impair ion regulation by inducing oxidative stress, mitochondrial dysfunction, and cell death of epidermal ionocytes and keratinocytes in zebrafish embryos. After exposure to various concentrations (10– 30 mM) of NH4Cl for 96 h, mortality increased up to 50 % and 100 % at 25 and 30 mM, respectively. Whole-embryo sodium, potassium, and calcium contents decreased at ≥10 mM, suggesting dysfunction of ion regulation. Numbers of H+-ATPase-rich (HR) cells and Na+/K+-ATPase-rich (NaR) cells (two ionocyte subtypes) were not significantly altered at 15 or 20 mM, while the mitochondrial abundance significantly decreased and reactive oxygen species (ROS) levels significantly increased in ionocytes. Moreover, caspase-3-dependent apoptosis was found in epidermal keratinocytes. Whole-embryo transcript levels of several genes involved in ion regulation, antioxidation, and apoptosis were upregulated after ammonia exposure. In conclusion, ammonia exposure was shown to induce oxidative stress and mitochondrial dysfunction in ionocytes and apoptosis in keratinocytes, thereby impairing ion regulation and ultimately leading to the death of zebrafish embryos.

期刊Comparative Biochemistry and Physiology Part - C: Toxicology and Pharmacology
出版狀態已發佈 - 2024 2月

ASJC Scopus subject areas

  • 生物化學
  • 生理學
  • 海洋科學
  • 動物科學與動物學
  • 毒理學
  • 細胞生物學
  • 健康、毒理學和誘變


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