Large-scale screening of disease model through ENU mutagenesis in mice

Manipulation of mouse genome has merged as one of the most important approaches for studying genefunction and establishing the disease model because of the high homology between human genome and mouse genome. In this study, the chemical mutagen ethylnitrosourea (ENU) was employed for inducing germ cell mutations in maleC57BL/6J mice. The first generation (G1) of the backcrossof these mutated mice, totally 3172, was screened for abnor-mal phenotypes on gross morphology, behavior, learning and memory, auditory brainstem response (ABR), electrocardio-gram (ECG), electroretinogram (ERG), flash-visual evoked potential (F-VEP), bone mineral density, and blood sugarlevel. 595 mice have been identified with specific dominantabnormalities. Fur color changes, eye defects and hearing loss occurred at the highest frequency. Abnormalities related to metabolism alteration are least frequent. Interestingly, eye defects displayed significant left-right asymmetry and sexpreference. Sex preference is also observed in mice with ab-normal bone mineral density. Among 104 G1 generation mutant mice examined for inheritability, 14 of them have been confirmed for passing abnormal phenotypes to their progenies. However, we did not observe behavior abnormali-ties of G1 mice to be inheritable, suggesting multi-gene con-trol for these complicated functions in mice. In conclusion, the generation of these mutants paves the way for under-standing molecular and cellular mechanisms of these ab-normal phenotypes, and accelerates the cloning of disease-related genes.