Date of Defense

2008

Department

Biological Sciences

First Advisor

Donald A. Kane, Biological Sciences

Abstract

The zebrafish mutant zombie arrests at mid-segmentation stages. At the cellular level, cells arrest at the metaphase, anaphase transition with chromosomes still aligned on the metaphase plate. Based on mapping data and the observed phenotype, the cell cycle gene CDC20 was tested as a putative candidate for the zombie mutation. CDC20 is an activator of the Anaphase Promoting Complex, an E3-ubiquitin ligase that labels substrates for degradation by proteasomes. Comparison of our PCR product sequences from mutants, the published genomic sequence and Expressed Sequence Tags led to the identification of a non-sense mutation in exon 7 of CDC20. To determine when the gene was expressed we measured the expression of CDC20 from early maternal stages through zygotic stages all the way to 24 hours. We found that the CDC20 gene is normally expressed at all times during early development. Furthermore, in mutant embryos we found non-sense mediated degradation of the mutant mRNA. Moreover, in situ hybridizations were performed to determine the location of expression of CDC20 at various stages as well as the amount of expression, further confirming the findings from the expression series.

Access Setting

Honors Thesis-Campus Only

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