Phenotypic and transcriptomic changes in zebrafish (Danio rerio) embryos/larvae following cypermethrin exposure

Area of Science:

• Environmental Toxicology
• Developmental Biology
• Genomics

Background:

• Cypermethrin, a type-II pyrethroid pesticide, is widely used but poses risks, especially to sensitive populations like children and pregnant women.
• The molecular mechanisms of cypermethrin-induced developmental toxicity are not fully understood.
• Zebrafish embryos serve as a valuable model for studying pesticide impacts on early development.

Purpose of the Study:

• To investigate the phenotypic and transcriptomic effects of cypermethrin exposure in zebrafish embryos.
• To elucidate the molecular mechanisms underlying cypermethrin's developmental toxicity.

Main Methods:

• Zebrafish embryos were exposed to cypermethrin (10 μg/L) at 24 and 48 hours postfertilization (hpf).
• Phenotypic assessments included hatching rate, heartbeat rate, and spinal curvature.
• Transcriptomic analysis utilized next-generation RNA sequencing (RNA-Seq) to identify gene expression changes.

Main Results:

• Cypermethrin exposure at 48 hpf induced phenotypic anomalies: delayed hatching, increased heartbeat, and spinal deformities.
• Transcriptomic analysis revealed altered gene expression related to visual/eye development.
• Gene functional profiling indicated disruption of the phototransduction pathway after 48 hours of exposure.
• A single gene, tnnt3b (fast muscle troponin isoform 3T), was upregulated in 24 hpf embryos.

Conclusions:

• Zebrafish embryos exposed to cypermethrin exhibit developmental toxicity, impacting various physiological and developmental parameters.
• Cypermethrin exposure disrupts visual development pathways, suggesting potential risks for visual impairment in sensitive populations.
• This study provides insights into the toxicological consequences of cypermethrin during embryonic development.