The dynamics of wildtype duf expression during embryonic muscle development has been characterized using mRNA in-situ hybridizations [4] and by the use of rP298 lacZ, [41] a P- nuclear lacZ insertion into the duf locus, which reproduces duf -like reporter- expression in all founder cells during embryonic [4] and adult myogenesis [11].
Skeletal muscle development in sheep is characterized by the sequential formation of primary, secondary and tertiary myofibres beginning approximately 32, 38 and 62-76 days of fetal life, respectively [ 1, 3, 4].
The bulk of tissue-specific splicing factors have been identified in these organ systems, and in turn the requirement of tissue specific AS in cardiac, neural, and muscle development has been further characterized in mouse models.
This morphological feature characterizes skeletal muscle development in mosaic hyperplasia, with small fibers containing central nuclei surrounding big fibers throughout the myotome (Johnston et al. 2003; Johnston and Hall 2004; Johnston et al. 2008; Steinbacher et al. 2007; Valente et al. 2013).
This subset of cases is characterized by ectopic muscle development (Miyagawa et al., 1998; Schumacher et al., 2003) and selection for activating mutations in CTNNB1, the gene encoding β-catenin (Koesters et al., 1999; Maiti et al., 2000).
A number of microRNAs, including muscle-specific and non-muscle-specific miRNAs, have been characterized as regulators of skeletal muscle development and diseases [ 17- 20] as well as of skeletal muscle remodeling [ 21].
Moreover, there is increasing evidence for the involvement of microRNA in myopathies [ 20- 22]; a number of microRNAs have been characterized as regulators of skeletal muscle development and diseases [ 23, 24] as well as of skeletal muscle remodeling [ 25].
The goals in the current study were to exploit the capability of a microarray approach to identify functional pathways of genes and thus characterize molecular events associated with muscle development and between genetic lines of turkeys with different growth rates.
These screens converged on MEF2, a pleiotropic transcription factor originally characterized as a key factor in muscle development (Bour et al., 1995; Lilly et al., 1995; Molkentin et al., 1995).
All these genes deserve in-depth studies: it would be of interest in particular to identify their individual function in fish muscle development and growth using antisens morpholino oligonucleotides and to further characterize their gene targets.
