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Big Blue® Transgenic Rodent Mutation Assay

BioReliance’s Big Blue® Transgenic Rodent Mutation (TRM) assay utilizes novel transgenic animal models bred for specific use in an assay defined by OECD Test Guideline 488, ”Transgenic Rodent Somatic and Germ Cell Gene Mutation Assays.” This assay allows the measurement of mutations in any tissue including germ cells and has been re-qualified for commercial use to meet OECD 488 test guideline standards.

After being originally co-developed and validated by BioReliance in the 1990s with funding from the National Institute for Environmental Health Sciences (NIEHS), Big Blue is once again being requested due to recent changes in regulatory guidelines and regulatory acceptance.

  • OECD Test Guideline 488 has been approved
  • Recommended by ECHA for REACH registration
  • Indicated by ICH S2(R1) as a follow-up to positive in vitro gene tox mutation assays
  • Recommended in draft ICH M7 as primary follow up assay for impurities with mutagenic mode of action

The Big Blue® Transgenic Rodent Mutation Assay (TRM) is an in vivo gene mutation assay currently available in mice. Gene mutation assays provide unique insight into chemicals with possible mutagenic mode of genotoxic action, as they specifically measure gene mutations, not DNA damage at the chromosome level as other frequently used assays. 

Consult with one of our genotoxicity experts to determine the toxicology assays that are best for your product needs or use the search tool to the right to browse our Big Blue® offerings.

Big Blue® Basics

Big Blue flow chart

Big Blue® mice are bred to have multiple copies of recoverable target genes integrated into their genome. Big Blue® animals are created by a microinjection of the lambda shuttle vector containing the cII gene into the pronucleus of fertilized eggs from either C57BL/6 mice or Fisher 344 rats.

The principle of the assay is that you can recover the lambda shuttle vector from genomic DNA and measure mutations in the lambda cII gene.

In a typical study, animals are dosed by oral gavage for 28 days. Tissues are then collected at day 31 after a three day period allowing DNA lesions to be fixed into the DNA and expressed as stable mutations. After collection, high molecular weight DNA is extracted from tissues of interest and purified, the shuttle vector recovered, packaged into phage, infected onto E. coli, and plated for plaque formation at two temperatures. cII mutant phage form plaques only at 24°C while all phage form plaques at 37°C. Mutation frequency is calculated by dividing the number of mutant plaques by the total number of plaques. Bioavailability (TK) measurements can be added to demonstrate exposure. OECD Test Guideline 488 allows for differing designs, so please consult a BioReliance representative to design a study that will best fit your needs and the regulatory guidelines.