Nucro-Technics – Mouse Lymphoma Assay

By: Nucro Technics  09-12-2011
Keywords: Mammalian Cells

The Mouse Lymphoma Assay (MLA), also called the in vitro mammalian cell gene mutation test, can be used to detect gene mutations induced by chemical substances and their metabolites.  In this assay, thymidine kinase (TK) proficient cells are exposed to the pyrimidine analogue trifluorothymidine (TFT), which causes the inhibition of cellular metabolism and halts further cell division. Cells deficient in TK, due to loss of heterozygosity, are resistant to the cytotoxic effects of TFT and are able to proliferate to form colonies in the presence of TFT. Therefore, an increase in the number of colonies in response to a test substance correlates to the mutagenic potential of the test substance. The study design follows the current OECD Guideline for Testing of Chemicals – 476, In vitro mammalian cell gene mutation test (1997). The assay can be performed in accordance with Good Laboratory Practices.

TK+/- cells are exposed to the test substance, both with and without metabolic activation, for a suitable period of time and subcultured to determine cytotoxicity and to allow phenotypic expression prior to mutant selection. Cytotoxicity is usually determined by measuring the relative cloning efficiency (survival) or relative total growth of the cultures after the treatment period. At least four analyzable concentrations of test substance are used in duplicate. Negative controls, consisting of solvent or vehicle alone in the treatment medium, and treated in the same way as the treatment groups should be included. The positive controls are Hycanthone and Cyclophosphamide. The treated cultures are maintained in growth medium for a sufficient period of time, to allow near-optimal phenotypic expression of induced mutations. Mutant frequency is determined by seeding known numbers of cells in medium containing the selective agent to detect mutant cells, and in medium without selective agent to determine the cloning efficiency (viability). After a suitable incubation time, colonies are counted. The mutant frequency is derived from the number of mutant colonies in selective medium and the number of colonies in non-selective medium.

Positive results for this assay indicate that the test substance induces gene mutations in the cultured mammalian cells used. Negative results indicate that, under the test conditions, the test substance does not induce gene mutations in the cultured mammalian cells used.

Experiment will start after receipt of signed protocol and the test substance. A draft report will be ready for review within 10-12 weeks after the experimental start date. Documents will be archived for six years.

Keywords: Mammalian Cells

Contact Nucro Technics

Email - none provided

Print this page

Other products and services from Nucro Technics


Nucro-Technics – Genetic Toxicology Services

NUCRO-TECHNICS is capable of conducting testing of new Active Pharmaceutical Ingredients, biotechnology products, chemical, and other agents. The following array of test systems satisfies the test requirements of the FDA, OECD, ICH, EPA, EU, EMEA, ISO, USP and Health Canada. IN-VITRO DNA DAMAGE IN MAMMALIAN CELLS.


Nucro-Technics – Bacterial Reverse Mutation Test (Ames Assay

Following OECD Guideline for the Testing of Chemicals – 471 Bacterial Reverse Mutation Test, four S. typhimurium strains, TA98, TA100, TA1535, and TA1537, and one E. coli strain, WP2 uvrA, will be used. Dose range-finding test, a primary and a confirmatory mutagenicity test, will be conducted with and without the presence of rat liver S9 that is induced with Aroclor 1254.


Nucro-Technics – Microbiology Services for the Pharmaceutical Industry

Environmental Audits, LAL, Particulate Matter Analyses, Antibiotic Analyses, Sterility Testing of drugs and devices, and bioburden determinations are some of the services that are offered. NUCRO-TECHNICS offers complete microbiological services for the Pharmaceutical, Biotechnology, Cosmetic, Medical Device, and Chemical Industries. The following is a brief listing of the type of Microbiology work that is done at Nucro-Technics.


Nucro-Technics – GLP Toxicology Services

All work is done to the appropriate standards, and subjects are maintained according to the requirements of the Animals for Research Act, the Guidelines of the Canadian Council on Animal Care, and the Association for Assessment and Accreditation of Laboratory Animal Care.


Nucro-Technics – Analytical Chemistry Testing

Each lab is equipped with state-of-the-art instrumentation to perform a wide range of chemical and instrumental analysis following procedures described in the USP/NF, BP, AOAC, EP, other compendia and clients’ procedures. NUCRO-TECHNICS provides a broad range of modern and classical Analytical Chemistry services to the Pharmaceutical, Biotechnology, Medical Device, and related industries.


Nucro-Technics: Contract Laboratory Services Summary

NUCRO-TECHNICS‘capabilities clearly distinguish us as a full service Pharmaceutical Contract Support Organization with qualifications and experience significantly different from those organizations that provide only testing services. Our employees have over 2000 years of combined practical experience and leadership in analyzing situations, developing strategies, creating new methods and procedures, and assisting clients with their products.


Nucro-Technics – Contract Bioanalytical Services

NUCRO-TECHNICS utilizes technologically advanced instrumentation to meet bioanalytical challenges and client demands using LC/MS/MS, HPLC and GC instrumentation to measure metabolite concentrations in biological matrices such as plasma, serum, CSF, urine, and tissue. The services provide bioanalytical support for non-clinical and clinical studies, including toxicokinetic studies, under both non-GLP and GLP conditions.