title: Optimization and validation of a colorimetric assay for Tetrahymena sp. survival.
abstract: A colorimetric assay based on the reduction of 3-(4,5-dimethyl-2-thiazol-2-yl)-2,5-diphenyl-2h-tetrazolium bromide (MTT), for the quantification of Tetrahymena sp. survival is described. An increase in the concentration of Tetrahymena sp. cells from 0 to 1 x 10(6) cells/ml produced a linear (R(2)=0.9965) increase in the optical density (OD, 570-630 nm), and dead cells (pre-exposed to 250 mg/l formalin for 4 h) did not produce a background reading. Cells exposed to sublethal concentrations to formalin (100 mg/l or less for 4 h) recovered their growth. Using the MTT assay, we determined that Tetrahymena sp. is sensitive to formalin, chloramine-T, hydrogen peroxide, copper sulfate and NaCl. The sensitivity increased with increasing chemical concentrations and exposure time. Tetrahymena sp. was resistant to bromex and malachite green. The use of this assay in drug screening for the development of treatments for tetrahymenosis and as a bioassay to evaluate the toxicity of environmental toxicants is discussed.
authors.affiliation: Albert Katz Department of Dryland Biotechnologies, The Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84990 Midreshet Ben Gurion, Israel. dzilberg@bgu.ac.il
authors.forename: Dina
authors.initials: D
authors.lastname: Zilberg
authors.forename: Tamar
authors.initials: T
authors.lastname: Sinai
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002700:Chloramines / Q000633:toxicity; D003124:Colorimetry; D019327:Copper Sulfate / Q000633:toxicity; D004353:Drug Evaluation, Preclinical; D004785:Environmental Pollutants / Q000633:toxicity; D005557:Formaldehyde / Q000633:toxicity; D006861:Hydrogen Peroxide / Q000633:toxicity; D012394:Rosaniline Dyes / Q000633:toxicity; D012965:Sodium Chloride / Q000633:toxicity; D013768:Tetrahymena / Q000166:cytology / Q000187:drug effects*; D013778:Tetrazolium Salts / Q000737:chemistry; D013844:Thiazoles / Q000737:chemistry; D014105:Tosyl Compounds / Q000633:toxicity
chemical_list: D002700:Chloramines; D004785:Environmental Pollutants; D012394:Rosaniline Dyes; D013778:Tetrazolium Salts; D013844:Thiazoles; D014105:Tosyl Compounds; C016300:chloramine-T; C005095:malachite green; D005557:Formaldehyde; D012965:Sodium Chloride; D006861:Hydrogen Peroxide; C022616:thiazolyl blue; D019327:Copper Sulfate