Chemical mutagenesis of the mouse genome: an overview

Abstract

The careful comparison of the phenotypic variations generated by different alleles at a given locus, including of course, those alleles with a deleterious effect, is often an important source of information for the understanding of gene functions. In fact, every time it is possible to match a specific alteration observed at the genomic level with a particular pathology, it is possible to establish a relationship between a gene and its function. When considered from this point of view, the production of new mutations by experimental mutagenesis appears as an alternative to the strategy of in vitro gene invalidation by homologous recombination in embryonic stem (ES) cells, with the advantage that experimental mutagenesis does not require any previous knowledge of the gene structure at the molecular level. Homologous recombination in ES cells is a 'gene driven' approach, in which mutant alleles are produced for those genes that we already know. Experimental mutagenesis, on the contrary, is a 'phenotype driven' approach, in which unknown genes are identified based on phenotypic changes. Also, while homologous recombination in ES cells requires a rather sophisticated technology, mutagenesis is simple to achieve but relies greatly on the efficiency of the mutagenic treatment as well as on the use of an accurate protocol for phenotyping. In this review, we will address a few comments about the different techniques that can be used for the induction of point mutations in the mouse germ line with special emphasis on chemical mutagenesis. We will also discuss the limitations of experimental mutagenesis and the necessity to look for alternative ways for the discovery of new genes and gene functions in the mouse.

Massively parallel sequencing of the mouse exome to accurately identify rare, induced mutations: an immediate source for thousands of new mouse models

“…Several previous studies have shown an abundance of TA–CG transitions and TA–AT transversions (ranging between 36–43% and 22–44% of changes, respectively [2,12,14,19]) and GC–CG transversions very rarely or never occur [14]. Of the validated 31 true-positive SNVs shown in table 1, 35.5, 38.7 and 0 per cent were TA–CG, TA–AT and GC–CG changes, respectively.…”

TILLING - a shortcut in functional genomics

“…ENU induces high frequencies of point mutations and is a more potent mutagen than EMS. ENU, which is an alkylating agent, leads to mispairing and, ultimately, results in base pair substitutions and, sometimes, base pair losses (Guénet 2004). In the cases of rats ( R. norvegicus ) and mice ( Mus musculus ), ENU is supplied at the dose of 50–100 mg/kg (Smits et al 2004 and Nolan et al 2000, respectively), whereas in a zebrafish ( D. rerio ) TILLING experiment, the mutagen was applied at a concentration of 3 mM (Wienholds et al 2003).…”

Ion Torrent sequencing for conducting genome-wide scans for mutation mapping analysis

“…The availability of high throughput sequencing data now makes “systems genetics” a possibility with the use of large-scale forward genetic screens for novel gene discovery (Caruana et al 2013; Hill et al 2013). Forward genetic screens in mice and other model organisms with chemical mutagenesis using ethylnitrosourea (ENU) has yielded new insights into the genetic basis for a wide spectrum of biological and disease processes (Arnold et al 2011; Guenet 2004), including genes that can cause congenital heart disease (CHD) (Shen et al 2005; Yu et al 2004; Zhang et al 2009). …”