Genetic Toxicology Screening Tests

The genetic toxicology screening tests are non-GLP studies that are designed to quickly determine the genotoxic potential of a substance.  These non-GLP tests have reduced sample requirements, using up to 60 times less compound, while giving relevant results in a fraction of the time and at substantially lower cost.  If test article information is limited, if flags for mutagenicity have been detected, or if large numbers of test articles have to be analyzed, the genetic toxicology screening tests may be a better way to start the genotoxicity evaluation.

Nucro-Technics offers  microplate version of the Bacterial Reverse Mutation Test (Regulatory category 1) and  In Vitro DNA Damage In Mammalian Cells (Regulatory category 2). The microplate tests have virtually 100% correlation to the corresponding regulatory assays.

Micro Ames Test

The Micro Ames test is a 24-well-plate version of the Bacterial Reverse Mutation Test.  It was designed to predict the results of the regulatory Ames assay (OECD 471).  This screening method uses the two most sensitive S. typhimurium strains for the detection of frame shift (TA98) and base-pair substitution (TA100).  The plate incorporation method is used with and without the presence of rat liver S9.  At least five exposure concentrations will be included in each experiment.  Duplicate wells will be used at each dose level in the mutagenicity tests. The highest tested dose mimics the regulatory requirement of 5 mg/plate for soluble non-toxic compounds in the full Ames assay.  Only 5 mg of test article is needed to run the Micro Ames Test.

Microplate in vitro Micronucleus Test

The Microplate in vitro Micronucleus test (Micro MN) is a method to detect aneugens and clastogens.  The test was designed to predict the results of the regulatory in vitro Micronucleus test (OECD 487). This screening method can be performed with primary human lymphocytes or CHO cells using the actin polymerisation inhibiton method.

Cultures are treated with at least 8 concentrations of test article from which the three highest analyzable treatments are selected for micronucleus scoring.  The highest tested is set at regulatory requirement (ICH) of 1 mg/mL for soluble non-toxic compounds in the full in vitro Micronucleus test assay.  Only 12 mg of test article is needed to run the Microplate in vitro Micronucleus test.  Cells are exposed to the test article for 3 hours with S9 fraction or for 20 h without S9 fraction. Slides are prepared for analysis and coded. Cytokinesis-Block Proliferation Index is determined to assess cell proliferation using at least 500 cells per test article concentration. At least 1000 bi-nucleated cells from each concentration are examined.

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