Microsatellite analysis of mouse TNF and Cypla2 loci for polymorphism: detection and evaluation of genetic contamination

The mouse TNF locus comprises tandemly arranged genes coding for Tnf _ (cachectin) and Tnf ß (lymphotoxin). The mouse TNF and Cypla2 loci were selected to detect simple sequence length polymorphism on genomic DNAs of four laboratory mouse strains. These polymorphisms might be useful in the search for tumor supressor genes involved in specific cancers. The primary aim of this work was to analyse the use of these polymophic microsatellite markers, which could differentiate between four typical laboratory mouse strains (i.e. BALB/c, C57BL/6, CBA as three inbred mouse strains and Syrian Hamster as an outbred strain) and the second was to define possible genetic contamination of a BALB/c mouse colony. In this study, we investigated the applicability of DNA fingerprinting using short tandem repeats (STRs) by the use of PAGE and silver staining. We found that all microsatellite DNA sequences varied in size in the TNF locus in the four strains tested, but for the Cypla2 locus no polymorphism was found within these strains. To our knowledge this is the first report of lack of polymorphism in the Cypla2 locus within these strains. The other techniques for inbred mouse identification were skin grafting and a coat colour test. We found no signs of rejection during skin grafting within the BALB/c mouse strain and also as expected all strains showed normal phenotypes. These experiments suggested lack of genetic heterogeneity in Cypla2 locus and no evidence of genetic contamination was also found in the BALB/c mouse