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Although many studies have been carried out to verify the involvement of the peripheral nervous system (PNS) in dystrophia myotonica (DM1) patients, the results remain controversial. The generation of DM1 transgenic mice displaying the human DM1 phenotype provides a useful tool to investigate the type and incidence of structural abnormalities in the PNS. In the present study, the morphological and morphometric analysis of semi-thin sections of sciatic and sural nerves, lumbar dorsal root ganglia (DRG) and lumbar spinal cords revealed that in DM1 transgenic mice carrying 300 CTG repeats, there is no change in the number and diameter of myelinated axons compared to wild type. Only a non-significant reduction in the percentage of thin myelinated axons was detected in electron micrographs of ultra-thin sciatic nerve sections. Analysis of the number of neurons did not reveal a loss in number of either sensory neurons in the lumbar DRG or motor neurons in the lumbar spinal cord in these DM1 mice. Furthermore, in hind limb muscle sections, stained with a neurofilament antibody and α-bungarotoxin, the intramuscular axon arborization appeared normal in DM1 mice and undistinguishable from that in wild-type mice. Moreover, in DM1 mice, there was no irregularity in the structure or an increase in the endplate area. Also statistical analysis did not show an increase in endplate density or in the concentration of acetylcholine receptors. Altogether, these results suggest that 300 CTG repeats are not sufficient to induce axonopathy, demyelination or neuronopathies in this transgenic mouse model. [ABSTRACT FROM AUTHOR]

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Copyright of Oncologie (Tech Science Press) is the property of Tech Science Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A 95-kb region of the mouse genome spanning the entire α-globin gene cluster was isolated as overlapping cosmid clones and characterized. In addition to the embryonic (ζ) and adult (α) genes, the cloned contig contains the complete N-methylpurine-DNA glycosylase ( MPG) gene, the a-globin-positive regulatory element (mHS-26), and a previously unidentified hypervariable region (named the mouse α-HVR). In mice, the distance between the MPG gene and mHS-26 is ~18 kb; between the mHS-26 and the ζ-gene, ~26 kb; from the ζ-gene to the 5′ end of the α-gene, ~16 kb; and the two α-genes are separated by ~12 kb. In human, the corresponding distances are ~27 kb, ~40 kb, ~19 kb, and ~3 kb respectively. The ±-HVR is located ~18 kb upstream of the mouse ζ-globin gene transcription start site and contains a variable copy number tandem repeat (VNTR) array of a 35-bp sequence rich in (G+C) content. The unit sequence of the HVR shares the short core sequence with the HVRs identified in the human a-gene cluster. Thus, this HVR may be a valuable evolutionary marker, as well as a useful genetic marker for the mouse. [ABSTRACT FROM AUTHOR]