Presence of chondroitin sulphate and requirement for heparan sulphate biosynthesis in the developing zebrafish inner ear.

Epithelial morphogenesis to form the semicircular canal ducts of the zebrafish inner ear depends on the production of the large glycosaminoglycan hyaluronan, which is thought to contribute to the driving force that pushes projections of epithelium into the lumen of the otic vesicle. Proteoglycans are also implicated in otic morphogenesis: several of the genes coding for proteoglycan core proteins, together with enzymes that synthesise and modify their polysaccharide chains, are expressed in the developing zebrafish inner ear. In this study, we demonstrate the highly specific localisation of chondroitin sulphate to the sites of epithelial projection outgrowth in the ear, present before any morphological deformation of the epithelium.

Identification of compounds that rescue otic and myelination defects in the zebrafish () mutant.

Adgrg6 (Gpr126) is an adhesion class G protein-coupled receptor with a conserved role in myelination of the peripheral nervous system. In the zebrafish, mutation of also results in defects in the inner ear: otic tissue fails to down-regulate gene expression and morphogenesis is disrupted. We have designed a whole-animal screen that tests for rescue of both up- and down-regulated gene expression in mutant embryos, together with analysis of weak and strong alleles.