Abstract
Most muscle originates from the myotomal compartment of the somites, paired structures flanking the neural tube. Whereas vertebrate embryos show molecular and morphological asymmetry about the left-right body axis, somitic myogenesis is thought to occur symmetrically. Here, we provide the first evidence that myotome pairs are transiently left-right asymmetric, with higher expression of a-skeletal actin and myosin light chain 3F (MLC3F) on the left side between embryonic day 9.5-10.25. In iv mutants with situs inversus, the asymmetric expression of a-skeletal actin and MLC3F was inverted, showing that this process is regulated by global left-right axis cues, initiated before gastrulation. However, although left-sided identity is later maintained by Pitx2 genes, we found that Pitx2c null embryos have normal left-biased expression of a-skeletal actin and MLC3F. Myotome asymmetry, therefore, is downstream of the iv mutation but upstream of, or unrelated to, the Pitx2c pathway. (C) 2004 Wiley-Liss, Inc
Original language | English |
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Pages (from-to) | 795 - 800 |
Number of pages | 6 |
Journal | Developmental Dynamics |
Volume | 231 |
Issue number | 4 |
DOIs | |
Publication status | Published - Dec 2004 |