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Testing of SHIRPA, a mouse phenotypic assessment protocol, on Dmd(mdx) and Dmd(mdx3cv) dystrophin-deficient mice
J A Rafael1, Y Nitta, J Peters
1Department of Human Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.
Abstract:
The SHIRPA protocol was proposed as a rapid, comprehensive screening method for qualitatively abnormal phenotypes in the mouse (Rogers et al., Mamm Genome 8, 711, 1997). This screening technique is currently being used to identify mutants induced by N-ethylnitrosourea (ENU) mutagenesis (Brown and Nolan, Hum Mol Genet 7, 1627, 1998). SHIRPA can be used to identify mutants with neuromuscular abnormalities, but the sensitivity of the protocol is unknown. We tested two dystrophin-deficient mutants Dmd(mdx) and Dmd(mdx3cv), both of which are indistinguishable from wild-type by a simple visual assessment, at different ages, using the primary screen of the SHIRPA protocol. The most dramatic observation was that both Dmd(mdx) and Dmd(mdx3cv) mice showed extreme fatigue after testing, while mice from the same C57BL strains appeared unaffected. Each strain of dystrophin-deficient mice showed a different profile in locomotor activity and deficiencies in the wire maneuver, righting reflex, and negative geotaxis tests. Furthermore, the wire maneuver test indicated an earlier onset of muscular impairment in Dmd(mdx) than Dmd(mdx3cv) mice. These data suggest that the SHIRPA primary screen is effective not only in identifying subtle neuromuscular mutants, but also in distinguishing qualitative differences between mutants with neuromuscular abnormalities.
Insights
The SHIRPA protocol effectively identifies subtle neuromuscular abnormalities in mice, revealing distinct fatigue profiles and motor deficits in dystrophin-deficient models like Dmd(mdx) and Dmd(mdx3cv). This screening method distinguishes between different types of muscular impairments.
Area of Science:
- Neuroscience
- Genetics
- Animal Models
Background:
- The SHIRPA protocol is a standard method for screening mouse phenotypes.
- Its sensitivity for detecting neuromuscular abnormalities is not well-established.
- N-ethylnitrosourea (ENU) mutagenesis is a common method for inducing genetic mutations in mice.
Purpose of the Study:
- To evaluate the sensitivity of the SHIRPA primary screen for detecting subtle neuromuscular abnormalities.
- To assess the ability of the SHIRPA protocol to differentiate between dystrophin-deficient mouse models.
- To investigate the onset and progression of muscular impairment in Dmd(mdx) and Dmd(mdx3cv) mice.
Main Methods:
- The SHIRPA primary screen was administered to Dmd(mdx) and Dmd(mdx3cv) mice at various ages.
- Locomotor activity, wire maneuver, righting reflex, and negative geotaxis were assessed.
- Phenotypes were compared to wild-type C57BL mice.
Main Results:
- Dystrophin-deficient mice (Dmd(mdx) and Dmd(mdx3cv)) exhibited significant fatigue post-testing, unlike wild-type controls.
- Distinct profiles in locomotor activity and motor function were observed between the two mutant strains.
- The wire maneuver test suggested an earlier onset of muscular impairment in Dmd(mdx) compared to Dmd(mdx3cv) mice.
Conclusions:
- The SHIRPA primary screen is a sensitive tool for identifying subtle neuromuscular defects in mice.
- The protocol can effectively distinguish qualitative differences between various neuromuscular mutant models.
- SHIRPA aids in characterizing the specific motor deficits and onset of disease in genetic models of muscular dystrophy.