Inducing mutations in the mouse genome with the chemical mutagen ethylnitrosourea

Abstract

When compared to other model organisms whose genome is sequenced, the number of mutations identified in the mouse appears extremely reduced and this situation seriously hampers our understanding of mammalian gene function(s). Another important consequence of this shortage is that a majority of human genetic diseases still await an animal model. To improve the situation, two strategies are currently used: the first makes use of embryonic stem cells, in which one can induce knockout mutations almost at will; the second consists of a genome-wide random chemical mutagenesis, followed by screening for mutant phenotypes and subsequent identification of the genetic alteration(s). Several projects are now in progress making use of one or the other of these strategies. Here, we report an original effort where we mutagenized BALB/c males, with the mutagen ethylnitrosourea. Offspring of these males were screened for dominant mutations and a three-generation breeding protocol was set to recover recessive mutations. Eleven mutations were identified (one dominant and ten recessives). Three of these mutations are new alleles (Otop1 mlh , Foxn1 sepe and probably rodador) at loci where mutations have already been reported, while 4 are new and original alleles (carc, eqlb, frqz, and Sacc). This result indicates that the mouse genome, as expected, is far from being saturated with mutations. More mutations would certainly be discovered using more sophisticated phenotyping protocols. Seven of the 11 new mutant alleles induced in our experiment have been localized on the genetic map as a first step towards positional cloning. Correspondence

Genetic and behavioral characterization of a Kmt2d mouse mutant, a new model for Kabuki Syndrome

“…BALB/cJ males treated with three ×100 mg/kg of ENU were crossed with nontreated BALB/cJ female. G1 males were crossed again with nontreated females and then G2 females were backcrossed to their father generating BALB/cJ‐ Kmt2d bapa /Kmt2d bapa mutant in the G3 progeny . Fourteen mutants were used to locate the chromosome carrying the bapa mutation.…”

“…A study developed in Brazil by Massironi et al with the purpose of inducing new mutations in BALB/cJ mice allowed the identification of 11 murine models. Among the recessive mutations identified by the study, one of them was called claps or “ bate palmas ” in Portuguese ( bapa ) and is characterized by abnormal movement of the hindlimbs when the mouse is lifted by the tail.…”

“…Considering that approximately 75% of ENU-induced mutations have been identified in exons, 7 some research groups utilize exome sequencing analyses to identify these mutations. 6,[8][9][10] A study developed in Brazil by Massironi et al 11 with the purpose of inducing new mutations in BALB/cJ mice allowed the identification of 11 murine models. Among the recessive mutations identified by the study, one of them was called claps or "bate palmas" in Portuguese (bapa) and is characterized by abnormal movement of the hindlimbs when the mouse is lifted by the tail.…”

Análise das alterações genéticas em exomas de camundongos

“…O sequenciamento completo do genoma de camundongo facilitou muito a procura e seleção de candidatos, e ficou ainda mais rápido e menos custoso com o advento do uso de tecnologias de sequenciamento de nova geração (NGS) na procura pelos candidatos (ARNOLD et al, 2011;BOLES et al, 2009;BULL et al, 2013;FAIRFIELD et al, 2011). caracterização dos candidatos para a mutação causal do fenótipo observado (MASSIRONI et al, 2006).…”

“…O acasalamento de fêmeas G2 com seu pai G1 dá origem a progênie G3, cujos fenótipos mutantes são de herança recessiva. Adaptado de (MASSIRONI et al, 2006).…”