| n the sea urchin there is a tandemly repeated U2 snRNA gene set that is expressed early in embryogenesis and inactivated after blastula stage. In addition, there is a constitutive gene set which is expressed in all cells. A tandemly repeated and a single copy U2 snRNA gene were isolated from the sea urchin L. variegatus. Upon microinjection into sea urchin zygotes, the genes showed temporal expression characteristic of an embryonic and a constitutive gene, respectively. Four cis-acting elements were identified within the promoter of each gene: the TATA box at... |
