Background: 

The zebrafish (Danio rerio) is a vertebrate which develops most organ functions within a few days after hatching. The genome is characterized and specific genes can be transiently ablated with morpholino antisense oligonucleotides (MOs) or over-expressed with plasmid or mRNA injection into the eggs. Several mutated strains exist. Muscles are organized and functional at hatching, and a time frame up to about 5 day is accessible for MOs. In the muscle field, several studies have focused on developmental aspects in this model, but functional data are very sparse.

Objective: 

To develop techniques and approaches for functional (physiological) studies of muscle in the zebrafish larvae and to apply these to study the function of key cytoskeletal proteins involved in muscle disease.

Methods: 

We have developed an approach to determine muscle contractile properties and structure in isolated larval muscle (Dou et al., 2008, J Gen Physiol 131:445–53).

Results: 

Zebrafish skeletal muscle have a comparatively fast phenotype. In the larvae at optimal length (about 2.15 m sarcomere length) the cells are oriented mainly in parallel with the long axis of the animal. Clear equatorial reflections can be recorded with small angle x-ray diffraction. We have identified two desmin genes in the larvae and can knock down mRNA and protein by selective MOs. This alteration is associated with a lower active tension, altered muscle structure, a wider filament spacing and altered responses to stretch during active contraction.

Conclusion: 

Skeletal muscle of Zebrafish larvae can be examined in vitro. Expression of muscle proteins can be manipulated and functional effects analyzed to provide a high-throughput analysis system for examining the role of normal and mutated muscle proteins.