Hexavalent chromium affected eyes development in zebrafish embryos

Area of Science:

• Environmental toxicology
• Developmental biology
• Ocular toxicology

Background:

• Hexavalent chromium (Cr(VI)) is a known environmental pollutant with demonstrated neurotoxic effects.
• The specific impact of Cr(VI) on eye development and its underlying mechanisms are not well understood.

Purpose of the Study:

• To investigate the effects of Cr(VI) on zebrafish embryo eye development.
• To elucidate the molecular mechanisms involved in Cr(VI)-induced ocular toxicity.

Main Methods:

• Zebrafish embryos were exposed to varying concentrations of Cr(VI).
• Assessed developmental toxicity, eye morphology, reactive oxygen species (ROS) production, apoptosis, and histopathological changes.
• Analyzed gene expression using qRT-PCR and whole-mount in situ hybridization (WISH).

Main Results:

• Cr(VI) exposure significantly reduced ocular axial dimensions and eye surface area in a dose-dependent manner.
• Increased ROS generation and apoptosis were observed in zebrafish eyes.
• Histopathological analysis revealed nuclear pyknosis in retinal cells and altered inter-retinal space.
• Downregulation of antioxidant genes and upregulation of pro-apoptotic genes were noted, with differential effects across retinal cell types.
• Opsin and crystallin gene expression showed specific, dose-dependent alterations.

Conclusions:

• Cr(VI) exposure induces significant ocular toxicity in zebrafish embryos.
• The toxicity mechanisms involve increased oxidative stress, apoptosis, and dysregulation of critical developmental and cellular genes.
• This study provides direct evidence of Cr(VI)-induced eye developmental abnormalities.