Date of Graduation


Document Type


Degree Type



Eberly College of Arts and Sciences



Committee Chair

James McGraw.


Three of the eight actin genes in the sea urchin Strongylocentrotus purpuratus were used for a comparative analysis. The cytoplasmic actin genes CyI, CyIIb and CyIIa are linked in the genome and encode very similar proteins. However, their spatial and temporal expression patterns are differentially regulated. The region of CyIIa upstream of the ATG and putative transcription start site was subcloned and sequenced. Sites of protein-DNA interaction were identified using DNaseI footprinting. Comparisons of this data with that previously obtained for CyI and CyIIb showed that while CyI and CyIIb share an identical CArG (or serum response element) and extensive sequence homology in the upstream region, homology with CyIIa is essentially limited to consensus protein binding sites, including the serum response element (SRE) and an octamer motif. Along with several other sites, the SRE and octamer were found to bind protein, though binding to CyIIa was altered in comparison to CyIIb. These data indicate that the CyIIa upstream sequences have diverged extensively since its proposed duplication from CyI. These changes in sequence are likely the cause of an altered set of transcription factor binding sites, which results in a pattern of expression that is markedly different from that of CyI/CyIIb.