Automated image analysis to improve bead ingestion toxicity test counts in the protozoan Tetrahymena pyriformis

AIMS

To improve bead ingestion counts in Tetrahymena pyriformis by automated image analysis as an alternative to direct-counts.

METHODS AND RESULTS

Fluorescent latex beads were added to T. pyriformis cultures for ingestion tests. The number of beads ingested by 25 cells was counted directly by epifluorescence microscopy and compared with similar data from image analysis. anova indicated that counts were not significantly different (P < 0.05). The image analysis particularly provided advantages in terms of speed.

CONCLUSIONS

The image analysis is superior to direct beads counting in T. pyriformis particularly in terms of speed of analysis.

SIGNIFICANCE AND IMPACT OF THE STUDY

The image analysis method is very rapid and will allow many more toxicological analyses to be undertaken with less operator error.

Phagocytosis of the protozoon Tetrahymena pyriformis as an endpoint in the estimation of cocaine salt and cocaine freebase toxicity

Cells of the ciliated protozoon Tetrahymena pyriformis strain W, grown in a peptone-yeast medium, usually contain many phagocytic vacuoles. The phagocytic activity of this protozoon was studied in vivo using heat-inactivated yeast stained with carmine after exposing the cultures for 1 hour to different doses of cocaine hydrochloride or cocaine freebase (crack) (0.5, 1 or 2 mg/100 ml of protozoan culture).The number of vacuoles formed indicated the phagocytic activity. Cocaine hydrochloride and crack caused a decrease of the phagocytic activity of the protozoon (p < 0.05) when compared to the control cultures. Furthermore, the two chemical forms of cocaine, salt and free-base respectively, caused quantitatively different effects on the phagocytic activity. Crack produced an extensive decrease in phagocytosis, compared to equal concentrations of cocaine hydrochloride. These results suggest a possible relationship between cocaine abuse and the suppression of phagocytosis that may contribute to the impairment of immunity in drug misusers.