Paraquat induced embryotoxicity on Xenopus laevis development

Area of Science:

• Environmental Toxicology
• Developmental Biology
• Herbicides

Background:

• Paraquat (PQ) is a widely used herbicide with potential environmental presence in aquatic ecosystems.
• Understanding the impact of herbicides on non-target species like amphibians is crucial for ecological risk assessment.

Purpose of the Study:

• To investigate the embryotoxic effects of Paraquat (PQ) on amphibian development using the Frog Embryo Teratogenesis Assay-Xenopus (FETAX).
• To determine the lethal and teratogenic concentrations of PQ and assess its impact on larval growth and morphology.

Main Methods:

• The Frog Embryo Teratogenesis Assay-Xenopus (FETAX) was employed to expose frog embryos to varying concentrations of PQ.
• Probit analysis was used to calculate LC(50) (lethal concentration for 50% of subjects) and TC(50) (teratogenic concentration for 50% of subjects).
• Histological examination was performed on malformed larvae to understand the cellular mechanisms of PQ toxicity.

Main Results:

• Paraquat (PQ) demonstrated high embryolethality, with an LC(50) of 0.138 mg/l and a TI(50) of 0.52, indicating it is not teratogenic.
• A significant malformation, ventral tail flexure, was observed in 29% of surviving larvae exposed to 0.125 mg/l PQ.
• Histological analysis revealed abnormal somites and affected myocytes, confirming PQ's toxicity to cell microfilaments.
• Even at the lowest tested concentration (0.0625 mg/l), PQ caused statistically significant growth retardation in larvae.

Conclusions:

• Paraquat (PQ) is highly embryotoxic to amphibian development, causing mortality, specific malformations, and growth retardation.
• The findings underscore the need for strict regulation of PQ usage in aquatic weed control programs to protect amphibian populations.
• PQ's mechanism of toxicity involves disruption of cell microfilaments, impacting myocyte development.