Selenium toxicity and bioaccumulation in selenium-enriched fly (Chrysomya megacephala) maggots

Area of Science:

• Biochemistry
• Animal Nutrition
• Environmental Toxicology

Background:

• Selenium (Se) is vital for human health.
• Chrysomya megacephala maggots (CMMs) are a protein-rich potential animal feed.
• Biological Se enrichment in CMMs could enhance their nutritional and toxicological profiles.

Purpose of the Study:

• To investigate the biological Se enrichment in CMMs using sodium selenite.
• To determine the effects of Se on CMM growth, accumulation, speciation, and enzyme activity.
• To explore the molecular mechanisms of Se response in CMMs via transcriptomics.

Main Methods:

• Exposure of CMMs to varying sodium selenite concentrations (0-70 mg kg⁻¹).
• Analysis of Se accumulation, speciation, and heavy metal concentrations (Cu, Zn, Cr, Cd).
• Measurement of enzymatic activities (antioxidant enzymes) and assessment of lipid peroxidation.
• Transcriptomic analysis to identify gene expression changes.

Main Results:

• Optimal CMM growth and Se accumulation occurred at 50 mg kg⁻¹ sodium selenite.
• Se exposure increased larval weight, protein content, and Se accumulation.
• Se enhanced Cu and Zn absorption, boosted antioxidant enzyme activity (SOD, CAT, GPX), and reduced lipid peroxidation.
• Se negatively impacted Cd and Cr absorption and modulated protein synthesis and enzyme activity.

Conclusions:

• Se-enriched CMMs exhibit improved nutritional value and antioxidant properties.
• Se-enriched CMMs can counteract the toxicity of heavy metals like Cd and Cr.
• Se supplementation is effective in enhancing the safety of CMMs for use as animal feed.