Desmin is a muscle-specific protein and a constitutive subunit of the 
intermediate filaments (IF) in skeletal, cardiac and smooth muscles. It is an 
early marker of skeletal muscle myogenesis. We have characterized a clone of 
desmin cDNA from an embryonic zebrafish (Danio rerio) cDNA library. The 
full-length cDNA comprised 1798 nucleotides, encoding a protein of 473 amino 
acids. The predicted amino acid sequence of the zebrafish desmin shares a high 
degree of similarity to other vertebrate desmins, but also contains a sequence 
at the carboxyl terminal of the tail domain that is unique to the zebrafish. It 
carries many features which are distinctive of IF subunit proteins. These 
include the T/SSYRRXF/Y motif in the head domain, and the intermediate filament 
signature consensus, [I/V]-X-[T/A/C/I]-Y-[R/K/H]-X-[L/M]-L-[D/E], located in the 
carboxyl terminus of the central helical rod. Unlike other 3' UTR sequences, the 
3' UTR of the zebrafish cDNA sequence has two CAYUG elements flanking a single 
polyadenylation site. The temporal and spatial expression patterns of desmin 
mRNA during early zebrafish development were studied. The onset of desmin 
expression occurred at the 1-3 somite stage (11 hpf). It increased throughout 
somitogenesis, with maximum expression at the Prim-6 stage (25 hpf), and 
decreasing expression towards the protruding-mouth stage (72 hpf). Desmin mRNA 
was initially localised exclusively to the somites, but was subsequently also 
detected in other musculature in the developing heart and fins. The onset of 
expression and the spatial localization of desmin mRNA in the zebrafish 
coincides with that reported for MyoD and myogenin.