Comparison of mutant frequencies at the transgenic lambda lacI and cII/cI loci in control and ENU-treated Big Blue® mice

✍ Scribed by D.M. Zimmer; P.R. Harbach; W.B. Mattes; C.S. Aaron

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 114 KB
• Volume: 33
• Category: Article
• ISSN: 0893-6692
• DOI: 10.1002/(sici)1098-2280(1999)33:3<249::aid-em9>3.0.co;2-f

✦ Synopsis

to the previously established Big Blue ® assay. Genomic DNA isolated from liver, spleen, and lung tissue of control or ethylnitrosourea (ENU)-treated Big Blue ® mice (100 mg/kg i.p., single dose) was packaged into phage (five animals, two packagings per DNA sample) which were simultaneously plated for lacI and cII/cI mutant frequency (MF) and titer. Mean MF of control animals was higher for cII/cI than lacI for all three tissues examined (spontaneous cII/cI MF divided by spontaneous lacI MF ϭ 2.9, 3.1, and 1.7 for liver, spleen, and lung, respectively). The differences were statistically significant for liver and spleen, but not lung. The ENU-induced MF measured by subtracting control MFs from ENU-treated MFs was higher in the cII/cI assay than lacI (liver ϭ 23.0 ϫ 10 -5 for cII/cI vs. 15.1 ϫ 10 -5 for lacI; spleen ϭ 64.8 ϫ 10 -5 for cII/cI vs. 36.1 ϫ 10 -5 for lacI; lung ϭ 17.1 ϫ 10 -5 for cII/cI vs. 15.8 ϫ 10 -5 for lacI ). Fold increase over control values measured by dividing MF of ENUtreated animals by appropriate control values was higher for lacI than cII/cI (liver ϭ 4.4-fold for lacI vs. 2.7 for cII/cI; spleen ϭ 13.1-fold for lacI vs. 8.4 for cII/cI; and lung ϭ 5.6-fold for lacI vs. 4.0 for cII/cI ). Despite these differences, overall results were similar for the two mutational endpoints. These results suggest that the cII/cI assay may be an acceptable alternative to lacI where transgenic mutation studies are indicated.