Electronic Thesis and Dissertation Repository


Master of Science




Karagiannis, Jim


In the fission yeast, Schizosaccharomyces pombe, stress upon the cell division machinery leads to the activation of a cytokinesis checkpoint. This checkpoint results in a delay in cell cycle progression and the prolonged maintenance of a cytokinesis competent cellular state. In this state the cell is able to continuously reform/repair the actomyosin ring until cell division is achieved. To uncover genes that play a role in enforcing this checkpoint, the actin depolymerizing drug Latrunculin A (LatA) was used to perturb the cytokinetic machinery in a set of 3400 viable haploid S. pombe gene deletion mutants. Thirty-eight gene deletion mutants hypersensitive to LatA were identified in this screen. Among this set of genes, the transcription factor adhesion defective protein 2 (adn2) showed one of the strongest phenotypes in response to LatA and was thus characterized further. Interestingly, live-cell imaging experiments showed that adn2 gene deletion mutants, while able to initially assemble the actomyosin ring, were unable to properly constrict the ring in the presence of LatA leading to cell division failure. Furthermore, over-expression experiments demonstrated that abnormally high levels of Adn2p result in morphological/cytokinetic phenotypes suggesting a possible dominant-negative effect.