Acute and Chronic Toxicity Assessment
​Acute Toxicity Testing
Assay Description
The Acute Toxicity Testing model is designed to evaluate the lethal dose (LD50) of chemicals, drugs, or environmental toxins in zebrafish embryos/larvae. This model assesses immediate toxicity, providing insights into mortality, hatching success, and early developmental disruptions.
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Testing Method: Zebrafish embryos are exposed to varying concentrations of the toxic compound. Survival rates are monitored at 24, 48, and 72 hours post-exposure.
Pathology
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External Morphology: Assessment of physical deformities such as pericardial edema, yolk sac edema, spinal curvature, and tail malformation.
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Organ Damage: Visual inspection of heart, liver, and blood vessels for any immediate pathological changes.
Biomarkers
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Gene Expression Analysis: Monitoring of apoptosis-related genes (e.g., caspases, p53) to assess cell death.
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Heat Shock Proteins (HSPs): Elevated HSPs indicate stress response to the toxin.
Screening Endpoints
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Mortality Rate: Percentage of embryos/larvae that survive or die at different time points.
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Hatching Success: Percentage of embryos that hatch within a defined time period.
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Behavioral Changes: Lack of spontaneous movement or abnormal swimming patterns.
Chronic Toxicity Testing
Assay Description
Chronic Toxicity Testing uses adult zebrafish models for prolonged exposure to assess the cumulative effects of a toxic substance over time. This model evaluates organ damage, reproductive toxicity, and overall survival.
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Testing Method: Adult zebrafish are exposed to the toxic compound over several weeks. Monitoring includes regular intervals to assess long-term effects on organ function and reproductive output.
Pathology
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Organ Pathology: Histological examination of liver, kidney, heart, and gonads to identify structural damage or degeneration.
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Inflammation: Signs of inflammatory responses in organs such as increased cellular infiltration and edema.
Biomarkers
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Liver Enzymes: Monitoring of ALT, AST, and LDH levels as indicators of liver damage.
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Heat Shock Proteins (HSPs): Elevated HSPs indicate stress response to the toxin.
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Hormonal Levels: Evaluation of thyroid, estrogen, and cortisol levels in blood samples to monitor endocrine disruption.
Screening Endpoints
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Survival Rate: Proportion of adult zebrafish that survive over the exposure period.
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Reproductive Toxicity: Reduced egg production, changes in fertilization rates, or deformities in offspring.
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Organ Damage: Histopathological evidence of organ damage (e.g., fibrosis, necrosis).