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Updated: Nov 28, 2025
Analysis of Oxidative Stress in Zebrafish Embryos
Published on: July 7, 2014
Molecular mechanisms of developmental toxicities of azoxystrobin and pyraclostrobin toward zebrafish (Danio rerio)
Chaeeun Kim1, Hyeseung Choe2, Jungeun Park1
1Department of Integrative Biology, Kyungpook National University, Daegu, 41566, Republic of Korea.
Abstract:
Azoxystrobin (AZ) and pyraclostrobin (PY) are strobilurin fungicides that inhibit fungal mitochondrial respiration. In this study, a representative model, zebrafish (Danio rerio), was used as a test species for acute and developmental toxicity. Survival and malformation rates were observed only PY-treated embryos, with an LC50 value of 77.75 ppb accompanied by a dramatic decrease in hatching rate, while AZ did not show great mortality. Morphological changes were observed in PY-treated embryos with the occurrence of pericadial edema at 25 ppb. A delay in growth was observed after treatment with pyraclostrobin at 50 ppb. Use of genetically engineered Tg(cmlc:EGFP) allowed fluorescence observation during heart development. PY interfered with normal heart development via upregulation of the nppa gene responsible for the expression of natriuretic peptides. Heart function was dramatically reduced as indicated by reduced heart rates. Increased expression of the nppa gene was also seen in AZ-treated embryos. The expression level of cyp24a1 was also up-regulated, while ugt1a1 and sult1st6 were down-regulated after treatment of zebrafish embryos with AZ or PY. Overall, strobilurin fungicides might inhibit normal heart formation and function within the range of concentrations tested.
Insights
Strobilurin fungicides, azoxystrobin and pyraclostrobin, impaired zebrafish heart development and function. Pyraclostrobin showed higher toxicity, affecting survival and hatching rates, while both fungicides impacted gene expression related to heart health.
Area of Science:
- Environmental Toxicology
- Developmental Biology
- Molecular Toxicology
Background:
- Strobilurin fungicides, like azoxystrobin (AZ) and pyraclostrobin (PY), are widely used agricultural chemicals.
- These fungicides function by inhibiting mitochondrial respiration in fungi.
- Their potential impact on non-target organisms, particularly during development, requires thorough investigation.
Purpose of the Study:
- To assess the acute and developmental toxicity of azoxystrobin (AZ) and pyraclostrobin (PY) in zebrafish (Danio rerio).
- To investigate the effects of these fungicides on zebrafish embryonic development, focusing on cardiac function and gene expression.
- To determine the median lethal concentration (LC50) and observe morphological changes induced by PY.
Main Methods:
- Zebrafish embryos were exposed to varying concentrations of AZ and PY for toxicity assessment.
- Morphological changes, survival, hatching rates, and growth delays were monitored.
- Genetically engineered Tg(cmlc:EGFP) zebrafish were used to observe heart development via fluorescence.
- Gene expression analysis was performed for nppa, cyp24a1, ugt1a1, and sult1st6.
Main Results:
- Pyraclostrobin (PY) exhibited significant toxicity, with an LC50 of 77.75 ppb, causing decreased survival and hatching rates.
- PY-treated embryos showed pericardial edema and growth delays at specific concentrations.
- Both AZ and PY treatments led to increased expression of the nppa gene, indicating interference with heart development.
- PY significantly reduced heart rate and function, while both fungicides altered the expression of other key genes (cyp24a1, ugt1a1, sult1st6).
Conclusions:
- Strobilurin fungicides, particularly pyraclostrobin, pose developmental risks to aquatic organisms like zebrafish.
- These fungicides can disrupt normal heart formation and function by altering critical gene expression pathways.
- Further research is needed to understand the long-term ecological implications of strobilurin fungicide exposure.
