Defense Date


Document Type


Degree Name

Master of Science


Human Genetics

First Advisor

James A. Lister


Colobomas are a type of eye defect characterized by the presence of a hole in certain eye structures. In this study, the roles of the zebrafish Otx genes, otx2 and otx1a, as well as the Rx family gene, rx3, in choroid fissure closure, the disruption of which leads to the onset of colobomas, were studied. It was observed that while the otx2 loss-of-function mutant, otx2hu3237 displayed small colobomas and the otx1a mutant, otx1a6del, did not exhibit any morphological eye defects, zebrafish possessing both mutations presented with a range of colobomas, some of which were more severe than otx2 single mutants and the size of the coloboma corresponded with the gene dosage of otx1a. Furthermore, it was also observed that additional knockdown of otx1b using morpholinos worsened the coloboma phenotype. Moreover, it was observed that rx3, while involved in RPE pigmentation, does not contribute to choroid fissure closure. Additionally, it appears that otx2 does not affect the rudimentary lens formation which is seen in loss-of-function rx3 mutants, i.e., eyeless mutants.


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VCU Theses and Dissertations

Date of Submission

May 2014