Flow cytometry assessment of cytotoxicity and reactive oxygen species generation by single and binary mixtures of cadmium, zinc and copper on populations of the ciliated protozoan Tetrahymena thermophila.

In the present study, we have assessed by flow cytometry, the cytotoxicity of the heavy metals Cd, Zn and Cu on populations of the ciliated protozoan Tetrahymena thermophila. The obtained LC(50) for these metals was estimated as 0.195mgCdl(-1), 3.

Ultrastructural alterations in ciliated protozoa under heavy metal exposure.

Transmission electron microscopy was used to study the ultrastructural changes induced by exposure to Cd or Zn in three species of ciliated protozoa: Colpoda steinii, Cyrtolophosis elongata and Drepanomonas revoluta. The main cytoplasmic alterations were partial mitochondrial degeneration, cytoplasmic vacuolisation, accumulation of membranous debris and autophagosome formation. At the nuclear level we detected nucleolar fusion in the macronucleus, and micronuclear membrane modifications.