The use of flow cytometric methods in acute and long-term in vitro testing

Toxicogenetic evaluation of dichlorophene in peripheral blood and in the cells of the immune system using molecular and flow cytometric approaches

Dichlorophene; a halogenated phenolic compound with wide applications as a fungicide, bactericide and antiprotozoan. Dichlorophene spray also has therapeutic use in the disease digital dermatitis. In guinea pigs, a few studies obtained mixed results in dicholorophene sensitization tests. In consideration of the fact, that the mechanism of its genotoxicity has not been adequately elucidated lead to present study assessing the acute in vivo toxicological impact in Rattus norvegicus. A systematic research has been made encompassing the use of molecular and flow cytometric approaches. The study was designed on blood cells for comet assay which revealed dichlorophene induced DNA damage in all exposures understandable in time dependent manner. The feasibility of this assay was also established as an effective, fast and accurate method with a great potential in biomonitoring. Contemporary molecular techniques were further engaged using leukocytes for the cell apoptosis/cycle and mitochondrial membrane potential employing propidium iodide staining and rhodamine 123 respectively. The effect on cell cycle phases and mitochondrial membrane permeability was analyzed through flow cytometry. These indicators exposed that dichlorophene decreased the mitochondrial membrane potential, altered the cell cycle and confirmed the DNA damage leading to apoptosis of the cells of the immune system accountable for immunotoxic effects of dichlorophene on rat leukocytes.

Genotoxicity and immunotoxic effects of 1,2-dichloroethane in Wistar rats

Dichloroethane is widely used as a solvent, degreasing agent and in a variety of commercial products, and is known for being a ubiquitous contaminant in the environment. Important sources principally include the emissions from industrial processes, improper consumption, storage, and disposal methods. In view of the fact that the mechanism of its genotoxicity has not been satisfactorily elucidated, the acute in vivo toxicological impact is assessed in Rattus norvegicus. A systematic investigation has been made involving the use of conventional methods along with molecular and flow cytometric approaches. The micronucleus and chromosomal aberration frequencies were significantly elevated in bone marrow cells exposed to three concentrations at multiple treatment durations indicating positive time- and dose-response relationships. The mitotic index significantly decreased in similar concentrations in contrast to normal control. Separate studies were performed on blood cells for comet assay. It revealed dichloroethane-induced DNA damage in all exposures readily explainable in a dose- and time-dependent manner. Recent molecular techniques were further employed using leukocytes for the cell apoptosis/cycle and mitochondrial membrane potential employing propidium iodide staining and rhodamine-123, respectively. The effect on mitochondrial membrane permeability, cell cycle phases, and the DNA damage was analyzed through flow cytometry. These indicators revealed dichloroethane treatment decreased the mitochondrial membrane potential, affected the cell cycle, and confirmed the DNA damage, leading to apoptosis of the cells of the immune system responsible for immunotoxic effects of dichloroethane on rat leukocytes.

High-throughput cytotoxicity screening by propidium iodide staining

This unit describes a system for the automated high-throughput analysis of cell cytotoxicity in 96-well and 384-well microplates. Discrete cell cultures are analyzed at rates of 40/min (approximately 2.5 min/96 wells, approximately 10 min/384 wells) and cytotoxicity is quantified on the basis of a combination of propidium iodide (PI) fluorescence analysis and cell counting performed by the flow cytometer. Only 2 microl is aspirated from a culture for analysis so that assays can be performed in small volumes to minimize reagent cost and usage.

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), 3.58mgZnl(-1) and 0.47mgCul(-1), respectively. As a result, the toxicity rank for this eukaryotic microorganism is Cd>Cu>>Zn. Using the same methodology and the Concentration Addition approach, the toxicity of binary mixtures of these metals was evaluated in order to detect the type of interaction between these metals. Results indicated that antagonism is the predominant interaction but it can change to additivity or even to synergism at high metal concentrations. Besides, the concentration ratio between metals plays also a crucial role in determining the type of metallic interaction, at least in Tetrahymena. Cytotoxicity data from single and bimetallic mixtures have been compared with those from selected microalgae, other species of ciliates, fish and mammalian cell lines and metazoan. By other hand, we have detected the mitochondrial generation of peroxides induced by both single and binary treatments with Cd, Zn and Cu on populations of Tetrahymena, using the specific fluorophore dyhidrorhodamine. The nature and concentrations of metal as well as the metallic ratio were important factors in reactive oxygen species production. All results found in T. thermophila are compared with previous reports in other organisms and, some explanations and hypothesis to support results are given, including the involvement of metallothioneins as antioxidants and their role in the binding of metal cations.