RETINOIC ACID IN THE ANTEROPOSTERIOR PATTERNING OF THE ZEBRAFISH TRUNK

Retinoic acid has been linked to pattern formation in the vertebrate a nteroposterior axis. This report describes the spatial and temporal di stributions of both endogenous retinoic acid and retinoic acid synthas e activity along the anteroposterior axis of neurulating zebrafish emb ryos, as detected by a transient transgenic assay and by a zymography bioassay. Both retinoic acid levels and synthase activity were found t o be highest in anterior regions of the trunk at all of the stages whi ch were analysed. The drug disulfiram inhibited retinoic acid synthase activity in the zebrafish trunk both in vitro and in vivo, and reduce d retinoic acid levels in vivo. Disulfiram treatment of neurulating em bryos resulted in larvae with hypertrophic wavy notochords; shortened spinal cords and deformed pectoral fins. The results support the hy po thesis that retinoic acid plays a role in the coordination of axial pa tterning at the developing node/zone of involution, as well as in the subsequent development of anterior trunk structures such as the fins.