UAS regulatory sequences drive expression of 600 interrupted CTG repeats (20 CTG units interrupted by the sequence CTCGA).
Larvae expressing Scer\GAL4Mef2.PR>Zzzz\CTGi600.Scer\UAS show reduced motility.
The body wall musculature of Scer\GAL4Mef2.PR>Zzzz\CTGi600.Scer\UAS third instar larvae display several abnormalities such as muscle splitting as well as loss of muscle fibers or presence of extra fibers. In addition, the muscles display a hyper-contracted phenotype.