Analysis of a cis-regulatory element of Hroth, the ascidian homologue of the otx genes, that drives its transcription in the anterior larval central nervous system of the ascidian, Halocynthia roretzi

Hroth, the ascidian homologue of vertebrate otx genes, is expressed in the anterior part of the larval ascidian central nervous system during its formation like vertebrate counterparts. The similarity of the expression pattern between Hroth and its vertebrate counterparts raise a possibility that a similar regulatory mechanism of otx transcription is present between ascidians and vertebrates. To understand the mechanism, we have analyzed transcription regulatory elements for the Hroth gene. We have demonstrated that at least three regulatory regions are present responsible for transcription of Hroth in the sensory vesicle, anterior trunk epidermis and a-line cells at the mid tailbud stage.