A microcapillary assay technique was developed to assess effects of pollutants on the chemoattraction of the ciliate, Tetruhyrnenu pyriformis. Parameters in the protocol such as starvation period, exposure period, and trough design were standardized in an effort to obtain consistent results.Cadmium, phenol, and naphthalene were tested for effects on ciliates' chemoattraction to 0.15% yeast extract. All three toxicants inhibited chemoattraction; cadmium had the greatest effect, followed by naphthalene and phenol, respectively. The percent inhibition of chemoattraction for each concentration was used to determine EC50 values for both 1 and 5 h exposures. Results show that the chemoattraction assay may provide a rapid, inexpensive, and sensitive asessment of aquatic toxicity. Inclusion of a protozoan assay fills the existing taxonomic gap in the routine battery of toxicity tests used for many hazard evaluations.

No abstract

The inhibitory effect of copper, 2,4‐D, Roundup, and an industrial effluent on chemoattraction responses of the ciliate Tetrahymena pyriformis was examined using a microcapillary technique. Each toxicant was tested with four replicates on three separate occasions. All toxicants inhibited chemoattraction at sublethal concentrations; although at lower concentrations of the herbicides, complete recovery to control levels was observed with longer exposures. Results indicate that sublethal concentrations of certain chemical pollutants may interfere with the ciliate's motility or chemosensory abilities. This may ultimately affect the ecosystem by inhibiting their ability to maintain their population levels and roles in the environment.

No abstract

No abstract