Аннотация:The H ox1 gene in the urochordate ascidian C iona intestinalis ( C i‐ H ox1 ) is expressed in the nerve cord and epidermis. We identified a nerve cord enhancer in the second intron of C i‐ H ox1 , and demonstrated that retinoic acid ( RA ) plays a major role in activating this enhancer. The enhancer contained a putative retinoic acid‐response element ( RARE ). Mutation of the RARE in the C i‐ H ox1 nerve cord enhancer only partially abolished the enhancer activity. Genes encoding RA synthase and the RA receptor were knocked down using specific antisense morpholino oligos ( MO s), and injection of embryos with these MO s resulted in the complete disappearance of epidermal expression of C i‐ H ox1 and reduction of neural expression. However, nerve cord expression was not completely repressed. These results suggest that the nerve cord enhancer is activated by two partially redundant pathways; one RA ‐dependent and one RA ‐independent.
Ключевые слова:Developmental Biology and Gene Regulation, Marine Ecology and Invasive Species, Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities
