Generation of an Allelic Series of Knock-In Mice Using Recombinase-Mediated Cassette Exchange (RMCE)

Abstract Phenotype-based mutagenesis experiments will increase the mouse mutant resource, generating mutations at previously unmarked loci as well as extending the allelic series at known loci. Mapping, molecular characterization, and phenotypic analysis of nine independent Pax6 mutations of the mouse recovered in mutagenesis experiments is presented. Seven mutations result in premature termination of translation and all express phenotypes characteristic of null alleles, suggesting that Pax6 function requires all domains to be intact. Of major interest is the identification of two possible hypomorph mutations: Heterozygotes express less severe phenotypes and homozygotes develop rudimentary eyes and nasal processes and survive up to 36 hr after birth. Pax64Neu results in an amino acid substitution within the third helix of the homeodomain. Three-dimensional modeling indicates that the amino acid substitution interrupts the homeodomain recognition α-helix, which is critical for DNA binding. Whereas cooperative dimer binding of the mutant homeodomain to a paired-class DNA target sequence was eliminated, weak monomer binding was observed. Thus, a residual function of the mutated homeodomain may explain the hypomorphic nature of the Pax64Neu allele. Pax67Neu is a base pair substitution in the Kozak sequence and results in a reduced level of Pax6 translation product. The Pax64Neu and Pax67Neu alleles may be very useful for gene-dosage studies.

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Microsatellite markers provide evidence for sexual reproduction of Mycosphaerella graminicola in Saskatchewan

Genome ◽

10.1139/g04-036 ◽

2004 ◽

Vol 47 (5) ◽

pp. 789-794 ◽

Cited By ~ 20

Author(s):

M Razavi ◽

G R Hughes

Keyword(s):

Genetic Diversity ◽

Genetic Variability ◽

Sexual Reproduction ◽

Primary Source ◽

Mycosphaerella Graminicola ◽

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Allelic Series ◽

Evolutionary Potential ◽

Wheat Field

This study examined the genetic structure of a Saskatchewan population of Mycosphaerella graminicola, cause of the foliar disease Septoria tritici blotch of wheat. Such knowledge is valuable for understanding the evolutionary potential of this pathogen and for developing control strategies based on host resistance. Nine pairs of single-locus microsatellite primers were used to analyze the genomic DNA of 90 isolates of M. graminicola that were collected using a hierarchical sampling procedure from different locations, leaves, and lesions within a wheat field near Saskatoon. Allelic series at eight different loci were detected. The number of alleles per locus ranged from one to five with an average of three alleles per locus. Genetic diversity values ranged from 0.04 to 0.67. Partitioning the total genetic variability into within- and among-location components revealed that 88% of the genetic variability occurred within locations, i.e., within areas of 1 m2, but relatively little variability occurred among locations. Low variability among locations and a high degree of variability within locations would result if the primary source of inoculum was airborne ascospores, which would be dispersed uniformly within the field. This finding was confirmed by gametic disequilibrium analysis and suggests that the sexual reproduction of M. graminicola occurs in Saskatchewan.Key words: Mycosphaerella graminicola, SSR markers, sexual reproduction, genetic diversity.

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Efficient recombinase-mediated cassette exchange at the AAVS1 locus in human embryonic stem cells using baculoviral vectors

Nucleic Acids Research ◽

10.1093/nar/gkr409 ◽

2011 ◽

Vol 39 (16) ◽

pp. e107-e107 ◽

Cited By ~ 32

Author(s):

Chrishan J. A. Ramachandra ◽

Mohammad Shahbazi ◽

Timothy W. X. Kwang ◽

Yukti Choudhury ◽

Xiao Ying Bak ◽

...

Keyword(s):

Stem Cells ◽

Embryonic Stem Cells ◽

Human Embryonic Stem Cells ◽

Embryonic Stem ◽

Cassette Exchange ◽

Aavs1 Locus

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Molecular definition of an allelic series of mutations disrupting the myostatin function and causing double-muscling in cattle

Mammalian Genome ◽

10.1007/s003359900727 ◽

1998 ◽

Vol 9 (3) ◽

pp. 210-213 ◽

Cited By ~ 280

Author(s):

Luc Grobet ◽

Dominique Poncelet ◽

Luis José Royo ◽

Benoit Brouwers ◽

Dimitri Pirottin ◽

...

Keyword(s):

Allelic Series ◽

Definition Of

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Position Effects Are Influenced by the Orientation of a Transgene with Respect to Flanking Chromatin

Molecular and Cellular Biology ◽

10.1128/mcb.21.1.298-309.2001 ◽

2001 ◽

Vol 21 (1) ◽

pp. 298-309 ◽

Cited By ~ 55

Author(s):

Yong-Qing Feng ◽

Matthew C. Lorincz ◽

Steve Fiering ◽

John M. Greally ◽

Eric E. Bouhassira

Keyword(s):

Mammalian Cells ◽

Transgene Expression ◽

Methylation Status ◽

Regulatory Elements ◽

Cell Populations ◽

Methylation Analysis ◽

Position Effects ◽

Methylation State ◽

Cassette Exchange

ABSTRACT We have inserted two expression cassettes at tagged reference chromosomal sites by using recombinase-mediated cassette exchange in mammalian cells. The three sites of integration displayed either stable or silencing position effects that were dominant over the different enhancers present in the cassettes. These position effects were strongly dependent on the orientation of the construct within the locus, with one orientation being permissive for expression and the other being nonpermissive. Orientation-specific silencing, which was observed at two of the three site tested, was associated with hypermethylation but not with changes in chromatin structure, as judged by DNase I hypersensitivity assays. Using CRE recombinase, we were able to switch in vivo the orientation of the transgenes from the permissive to the nonpermissive orientation and vice versa. Switching from the permissive to the nonpermissive orientation led to silencing, but switching from the nonpermissive to the permissive orientation did not lead to reactivation of the transgene. Instead, transgene expression occurred dynamically by transcriptional oscillations, with 10 to 20% of the cells expressing at any given time. This result suggested that the cassette had been imprinted (epigenetically tagged) while it was in the nonpermissive orientation. Methylation analysis revealed that the methylation state of the inverted cassettes resembled that of silenced cassettes except that the enhancer had selectively lost some of its methylation. Sorting of the expressing and nonexpressing cell populations provided evidence that the transcriptional oscillations of the epigenetically tagged cassette are associated with changes in the methylation status of regulatory elements in the transgene. This suggests that transgene methylation is more dynamic than was previously assumed.

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Recombinase-Mediated Cassette Exchange Using Adenoviral Vectors

Methods in Molecular Biology - Site-Specific Recombinases ◽

10.1007/978-1-4939-7169-5_9 ◽

2017 ◽

pp. 127-150 ◽

Cited By ~ 1

Author(s):

Andreas F. Kolb ◽

Christopher Knowles ◽

Patrikas Pultinevicius ◽

Jennifer A. Harbottle ◽

Linda Petrie ◽

...

Keyword(s):

Adenoviral Vectors ◽

Cassette Exchange

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An Allelic Series of Mutations in the Kit ligand Gene of Mice. I. Identification of Point Mutations in Seven Ethylnitrosourea-Induced KitlSteel Alleles

Genetics ◽

10.1093/genetics/162.1.331 ◽

2002 ◽

Vol 162 (1) ◽

pp. 331-340 ◽

Cited By ~ 1

Author(s):

S Rajaraman ◽

W S Davis ◽

A Mahakali-Zama ◽

H K Evans ◽

L B Russell ◽

...

Keyword(s):

Receptor Tyrosine Kinase ◽

Stem Cell Factor ◽

Genetic Resource ◽

Point Mutations ◽

Exon Skipping ◽

Missense Mutations ◽

Allelic Series ◽

Kit Ligand ◽

Kit Receptor ◽

Induced Mutants

Abstract An allelic series of mutations is an extremely valuable genetic resource for understanding gene function. Here we describe eight mutant alleles at the Steel (Sl) locus of mice that were induced with N-ethyl-N-nitrosourea (ENU). The product of the Sl locus is Kit ligand (or Kitl; also known as mast cell growth factor, stem cell factor, and Steel factor), which is a member of the helical cytokine superfamily and is the ligand for the Kit receptor tyrosine kinase. Seven of the eight ENU-induced KitlSl alleles, of which five cause missense mutations, one causes a nonsense mutation and exon skipping, and one affects a splice site, were found to contain point mutations in Kitl. Interestingly, each of the five missense mutations affects residues that are within, or very near, conserved α-helical domains of Kitl. These ENU-induced mutants should provide important information on structural requirements for function of Kitl and other helical cytokines.

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