5-Fluorouracil accumulation in green microalgae and its biogenetic transfer into ciliate protozoan

Area of Science:

• Environmental Science
• Toxicology
• Microbiology

Background:

• The anticancer drug 5-fluorouracil (5-FU) is a widely used chemotherapeutic agent.
• Understanding the environmental fate and ecological impact of pharmaceuticals is crucial.

Purpose of the Study:

• To investigate the ecotoxicity and bioaccumulation of 5-fluorouracil in the green microalga Scenedesmus vacuolatus.
• To determine the potential for 5-FU transfer through the food chain via microalgal biomass.

Main Methods:

• Exposure of Scenedesmus vacuolatus to 5-FU.
• Quantification of 5-FU bioaccumulation using a bioaccumulation factor.
• Integration of 5-FU into microalgal DNA and RNA.
• Feeding experiments with the protozoan Tetrahymena pyriformis.
• Radioactivity measurements to track labeled 5-FU transfer.

Main Results:

• 5-fluorouracil exhibited acute toxicity, inhibiting the growth of Scenedesmus vacuolatus.
• High bioaccumulation of 5-FU (1.84 × 10^4) was observed in microalgae biomass.
• 5-FU integrated into the microalgal genome (DNA and RNA).
• Labeled microalgal DNA/RNA, containing 5-FU, was transferred to Tetrahymena pyriformis upon ingestion.
• Radioactivity confirmed the presence of labeled material in predator food vacuoles, but not in the predator's genome.

Conclusions:

• 5-fluorouracil poses an ecological risk to primary producers like microalgae.
• The bioaccumulation and genomic integration of 5-FU facilitate its transfer to higher trophic levels.
• While the drug itself may not integrate into the predator's genome, its presence in ingested biomass indicates a potential pathway for environmental contamination and biomagnification.