Expression of mature muscle genes decreases with regeneration in tail and limb. (a) Real Time PCR analysis of tail regeneration. myod gene expression does not significantly change in the distal stump between 0 and 3 dpa, while cardiac α actin (car) and myosin heavy chain 4 (myh4) have 5-fold lower expression at 3 dpa. n = three independent experiments of 10 tail samples per time point. (b) Real Time PCR analysis of stage 54 limb regeneration. Three samples were used: 0 dpa zeugopod; 3 dpa zeugopod; growth control (GC)-not amputated, three days older zeugopod. myod, myogenin and car levels are the same between 0 and 3 dpa. However, comparing 3 dpa with GC, we observed a significant lower expression of myod, myogenin and car in the regenerating limb. n = four independent experiments of 10 or 20 limb samples per time point. Results were normalized for ornithine decarboxylase (odc) expression and relativized to the time points with highest expression (0 dpa for tail and GC for limb). Error bars: standard error. Asterisk: p value < 0.01; Student's t test.