A comprehensive and comparative phenotypic analysis of the collaborative founder strains identifies new and known phenotypes

in Mammalian Genome (2020)

Aey2, a new mutation in the betaB2-crystallin-encoding gene of the mouse.

in Investigative Ophthalmology and Visual Science (2001), 42(7), 1574-80

PURPOSE: During an ethylnitrosourea (ENU) mutagenesis screen, mice were tested for the occurrence of dominant cataracts. One particular mutant was found that caused progressive opacity and was referred to ... [more ▼]

PURPOSE: During an ethylnitrosourea (ENU) mutagenesis screen, mice were tested for the occurrence of dominant cataracts. One particular mutant was found that caused progressive opacity and was referred to as Aey2. The purpose of the study was to provide a morphologic description, to map the mutant gene, and to characterize the underlying molecular lesion. METHODS: Isolated lenses were photographed, and histologic sections of the eye were analyzed according to standard procedures. Linkage analysis was performed using a set of microsatellite markers covering all autosomal chromosomes. cDNA from candidate genes was amplified after reverse transcription of lens mRNA. RESULTS: The cortical opacification visible at eye opening progressed to an anterior suture cataract and reached its final phenotype as total opacity at 8 weeks of age. There was no obvious difference between heterozygous and homozygous mutants. The mutation was mapped to chromosome 5 proximal to the marker D5Mit138 (8.7 +/- 4.2 centimorgan [cM]) and distal to D5Mit15 (12.8 +/- 5.4 cM). No recombinations were observed to the markers D5Mit10 and D5Mit25. This position makes the genes within the betaA4/betaB-crystallin gene cluster excellent candidate genes. Sequence analysis revealed a mutation of T-->A at position 553 in the Crybb2 gene, leading to an exchange of Val for GLU: It affects the same region of the Crybb2 gene as in the Philly mouse. Correspondingly, the loss of the fourth Greek key motif is to be expected. CONCLUSIONS: The Aey2 mutant represents the second allele of Crybb2 in mice. Because an increasing number of beta- and gamma-crystallin mutations have been reported, a detailed phenotype-genotype correlation will allow a clearer functional understanding of beta- and gamma-crystallins. [less ▲]

Enu mouse mutagenesis: generation of mouse mutants with aberrant plasma IgE levels.

in International Archives of Allergy and Applied Immunology (2001), 124(1-3), 25-8

BACKGROUND: The ENU Mouse Mutagenesis Project aims at a large-scale, systematic production of mouse mutants using the alkylating agent ethyl-nitrosourea (ENU). Offspring of mutagenized mice are subjected ... [more ▼]

BACKGROUND: The ENU Mouse Mutagenesis Project aims at a large-scale, systematic production of mouse mutants using the alkylating agent ethyl-nitrosourea (ENU). Offspring of mutagenized mice are subjected to a multiparameter screen to detect alterations in various phenotypes with the ultimate goal of identifying novel genes relevant for the expression of the phenotype. Using this approach, we have analyzed plasma IgE concentrations to identify mouse mutants with aberrant plasma IgE levels. METHODS AND RESULTS: ENU-mutagenized male C3HeB/FeJ were mated to wild-type females to produce F1 offspring. F1 animals were analyzed for alterations in their plasma IgE concentrations that showed a dominant mode of inheritance, or bred further to screen for recessive phenotypes. Plasma IgE concentrations were determined by ELISA and a normal range for plasma IgE was established using C3HeB/FeJ wild-type animals. So far we have tested 6568 F1 animals. Repeated testing confirmed a stable aberrant IgE phenotype in 124 animals. To confirm the genetic basis of the observed phenotype, these mice were subjected to confirmation crossing. Currently we have established 9 independent mutant mouse lines (3 with high plasma IgE and 6 with plasma IgE below detection limit) that have been genetically confirmed and additional 24 variant mouse lines are currently undergoing confirmation testing. CONCLUSION: ENU mouse mutagenesis allowed us to generate and identify mouse mutants with aberrant plasma IgE levels, which may be used to characterize novel genes involved in IgE regulation and may serve as animal models for IgE-mediated diseases. [less ▲]

The Notch ligand Jagged1 is required for inner ear sensory development.

in Proceedings of the National Academy of Sciences of the United States of America (2001), 98(7), 3873-8

Within the mammalian inner ear there are six separate sensory regions that subserve the functions of hearing and balance, although how these sensory regions become specified remains unknown. Each sensory ... [more ▼]

Within the mammalian inner ear there are six separate sensory regions that subserve the functions of hearing and balance, although how these sensory regions become specified remains unknown. Each sensory region is populated by two cell types, the mechanosensory hair cell and the supporting cell, which are arranged in a mosaic in which each hair cell is surrounded by supporting cells. The proposed mechanism for creating the sensory mosaic is lateral inhibition mediated by the Notch signaling pathway. However, one of the Notch ligands, Jagged1 (Jag1), does not show an expression pattern wholly consistent with a role in lateral inhibition, as it marks the sensory patches from very early in their development--presumably long before cells make their final fate decisions. It has been proposed that Jag1 has a role in specifying sensory versus nonsensory epithelium within the ear [Adam, J., Myat, A., Roux, I. L., Eddison, M., Henrique, D., Ish-Horowicz, D. & Lewis, J. (1998) Development (Cambridge, U.K.) 125, 4645--4654]. Here we provide experimental evidence that Notch signaling may be involved in specifying sensory regions by showing that a dominant mouse mutant headturner (Htu) contains a missense mutation in the Jag1 gene and displays missing posterior and sometimes anterior ampullae, structures that house the sensory cristae. Htu/+ mutants also demonstrate a significant reduction in the numbers of outer hair cells in the organ of Corti. Because lateral inhibition mediated by Notch predicts that disruptions in this pathway would lead to an increase in hair cells, we believe these data indicate an earlier role for Notch within the inner ear. [less ▲]

The biochemical metabolite screen in the Munich ENU Mouse Mutagenesis Project: determination of amino acids and acylcarnitines by tandem mass spectrometry.

in Mammalian Genome (2000), 11(7), 547-51

BACKGROUND: Gene mutations often result in altered protein expression and, in turn, lead to changes in metabolite levels in one or more distinct biochemical pathways. Traditional analytical methods for ... [more ▼]

BACKGROUND: Gene mutations often result in altered protein expression and, in turn, lead to changes in metabolite levels in one or more distinct biochemical pathways. Traditional analytical methods for metabolite determination are usually time consuming, expensive, and, thus, not suitable for high throughput analysis. However, recent developments in electrospray-tandem-mass-spectrometry allow comprehensive metabolite scanning from very small amounts of blood with high speed, cost effectiveness, and accuracy. METHODS: A blood spot from a filter paper equivalent to 3 microl of blood was punched out and transferred to a 96-well microtiter plate. After addition of a set of 14 stable isotope-labeled internal standards, amino acids and acylcarnitines were extracted with methanol. The dried residue was derivatized with butanolic hydrochloric acid and subjected to MSMS analysis. RESULTS: Acyl-carnitines were all determined by a precursor ion scan of 85 Da. Neutral loss scanning of 102 Da was suitable for the quantitation of threonine, serine, proline, histidine, alanine, aspartic acid, glutamic acid, methionine, tyrosine, phenylalanine, isoleucine/leucine and valine. Glycine was detected by a loss of a 56-Da fragment, whereas a 119-Da loss was suitable for the measurement of citrulline, ornithine, arginine, and lysine. Specific problems encountered: owing to their identical molecular weight, isoleucine and leucine could not be quantitated separately, and, owing to their instability, glutamine and asparagine were found to be decarboxylated to their respective acids. Determination was linear over the concentration range tested (20 to 1000 micromol/L), and intraassay and interassay coefficients of variation were in the range of 10-15%. CONCLUSION: ESI-MSMS proved to be a highly sensitive, linear, and sufficiently precise method for the quantitative determination of amino acids and acylcarnitines in mouse blood, allowing large-scale screening applications when speed and cost effectiveness are mandatory. [less ▲]

Screening for dysmorphological abnormalities--a powerful tool to isolate new mouse mutants.

in Mammalian Genome (2000), 11(7), 528-30

From developmental biology to developmental toxicology.

in Annals of the New York Academy of Sciences (2000), 919

Progress derived from the human genome project will have tremendous impact on toxicology. Questions concerning genetic susceptibility or resistance to toxic compound exposure and the dissection of the ... [more ▼]

Progress derived from the human genome project will have tremendous impact on toxicology. Questions concerning genetic susceptibility or resistance to toxic compound exposure and the dissection of the molecular mechanisms involved will be at the forefront of future toxicological research. In recent years, it was recognized that many of the molecular control mechanisms of embryogenesis have been conserved during evolution. The relevance of these observations for toxicology and the application of genetic approaches using mouse mutants as a tool for functional genome analysis are discussed. [less ▲]

Tailchaser (Tlc): a new mouse mutation affecting hair bundle differentiation and hair cell survival.

in Journal of Neurocytology (1999), 28(10-11), 969-85

We have undertaken a phenotypic approach in the mouse to identifying molecules involved in inner ear function by N-ethyl-N-nitrosourea mutagenesis followed by screening for new dominant mutations ... [more ▼]

We have undertaken a phenotypic approach in the mouse to identifying molecules involved in inner ear function by N-ethyl-N-nitrosourea mutagenesis followed by screening for new dominant mutations affecting hearing or balance. The pathology and genetic mapping of the first of these new mutants, tailchaser (Tlc), is described here. Tlc/+ mutants display classic behavioural symptoms of a vestibular dysfunction, including head-shaking and circling. Behavioural testing of ageing mice revealed a gradual deterioration of both hearing and balance function, indicating that the pathology caused by the Tlc mutation is progressive, similar to many dominant nonsyndromic deafnesses in humans. Based on scanning electron microscopy (SEM) studies, Tlc clearly plays a developmental role in the hair cells of the cochlea since the stereocilia bundles fail to form the characteristic V-shape pattern around the time of birth. By young adult stages, Tlc/+ outer hair bundles are grossly disorganised although inner hair bundles appear relatively normal by SEM. Increased compound action potential thresholds revealed that the Tlc/+ cochlear hair cells were not functioning normally in young adults. Similar to inner hair cells, the hair bundles of the vestibular hair cells also do not appear grossly disordered. However, all types of hair cells in the Tlc/+ inner ear eventually degenerate, apparently regardless of the degree of organisation of their hair bundles. We have mapped the Tlc mutation to a 12 cM region of chromosome 2, between D2Mit164 and D2Mit423. Based on the mode of inheritance and map location, Tlc appears to be a novel mouse mutation affecting both hair cell survival and stereocilia bundle development. [less ▲]

We need more mutants: Plans for a large scale ENU mouse mutagenesis screen

in OECD Economics Department Working Papers (1998), (98), 103-111