Mouse Genome Informatics
hm1
    Musktm1.1Vwi/Musktm1.1Vwi
involves: C57BL/6J
Key:
phenotype observed in females WTSI Wellcome Trust Sanger Institute
phenotype observed in males EuPh Europhenome
N normal phenotype
mortality/aging


Mouse Genome Informatics
ht2
    Musktm1.1Vwi/Musktm2Vwi
Not Specified
Key:
phenotype observed in females WTSI Wellcome Trust Sanger Institute
phenotype observed in males EuPh Europhenome
N normal phenotype
mortality/aging
• 40% of male mice die between the second and fourth month of life
• however, female mice do not exhibit premature death

muscle
• after 3 weeks, mice exhibit reduced muscle mass compared to wild type mice in the pelvic and scapular regions
• muscle strength produced by single or titanic stimuli is reduced compared to in wild-type mice while the degree of fatigue remains the same
• the time to peak or contraction time and half relaxation time of a direct-evoked single twitch is prolonged compared to in wild-type muscle
• unlike in wild-type mice, the diaphragm is unable to maintain unique tentanic contractions or repetitive titanic contractions indicating reduced fatigue resistance
• the twitch to titanic ratio of the diaphragm after nerve stimulation is double wild-type
• mice exhibit weakness of the pelvic muscle that leads to a waddling gait unlike

nervous system
• axons of the nerves innervating the diaphragm exhibit overgrowth and increased branching compared to in wild-type mice
• axons are increased in length and extend from the main nerve trunk to the medial and/or lateral side of the diaphragm compared to in wild-type mice
• unlike in wild-type mice, axons at the NMJs in the diaphragm exhibit sprouting and retraction bulbs and fail to form the normal Pretzel-like shaped post-synpatic structure
• as early as P0, endplates in the diaphragm NMJs are smaller and more spread out than in wild-type mice
• at P25 and P45, diaphragm neuromuscular junctions (NMJs) lack a well-defined central endplate unlike in wild-type mice
• at P45, the NMJs of the intercostals, diaphragm and tibialis anterior exhibit altered post-synaptic structures compared to in wild-type mice
• at P120, soleus NMJs exhibit few junctional folds, the distance between the post-synaptic membrane and myofibril compartment is reduced compared to in wild-type mice, mitochondria invade the subsynpatic space, subsynaptic nuclei disappear, and in many cases the sole plate is abolished
• however, extensor digitorum longus NMJs are normal
• the amplitude of endplate potentials is 76% of wild-type
• the mean peak frequency of miniature end plate potential of the diaphragm is reduced compared to in wild-type diaphragms
• however, the amplitudes of miniature end plate potentials is normal

behavior/neurological
• in a rotarod test, the latency to fall is half of wild-type
• mice exhibit a progressive loss of grip strength beginning at P21 and reaching a 30% reduction by P60 compared to wild-type mice
• mice develop a waddling gait

skeleton
• after 3 weeks, mice exhibit deformation of the backbone and increasing kyphosis unlike in wild-type mice
• at P45, mice exhibit curvatures of the spine in the thoracic and lumbar vertebrae

growth/size/body
• by 2 months of age mice weigh 75% of wild-type

cellular
• axons of the nerves innervating the diaphragm exhibit overgrowth and increased branching compared to in wild-type mice


Mouse Genome Informatics
cn3
    Musktm1Vwi/Musktm1.1Vwi
Tg(Ckmm-cre)5Khn/0

involves: C57BL/6J * FVB
Key:
phenotype observed in females WTSI Wellcome Trust Sanger Institute
phenotype observed in males EuPh Europhenome
N normal phenotype
mortality/aging
• die before P30

muscle
• at around 2 to 3 weeks of age, develop severe muscle weakness with impaired mobility and difficulty breathing, eating, and drinking

nervous system
• in older mice, phrenic nerve innervation is seen outside the central band of the diaphragm muscle
• from P20 on, endplates in the diaphragm show decreased acetylcholine receptor densities and begin to disintegrate
• after P20 neuromuscular junction endplates are seen outside the central band where they are normally confined

behavior/neurological
• grip strength from P12 onwards does not increase, unlike in wild-type mice

growth/size/body
• normal weight gain until about 3 to 4 weeks of age then weight gain stops and weight loss is seen

skeleton