Identification of starmaker-like in medaka as a putative target gene of Pax2 in the otic vesicle

Otoliths in bony fishes are involved in the function of the ear in the senses of balance and hearing. In a large-scale random in situ hybridization screen of genes expressed in the medaka developing ear, we identified starmaker-like (stm-l) gene, a novel homologue of zebrafish starmaker and human dentine sialophosphoprotein (dspp) gene. Despite the absence of sequence similarity between these genes, here we describe their similar genomic structure and expression patterns hinting for a conserved function. In medaka fry, stm-l is expressed in various organs such as otoliths, teeth, gills, and kidney. Additionally, our results provide evidence that stm-l is a putative downstream target gene of Pax2 transcription factor and Pax2 itself has a promoting function in otolith formation.