Positioning and assembly of division machinery in fission yeast

Abstract

In this study, I address some questions related to the mechanisms of division plane positioning and actomyosin ring assembly in fission yeast. Results are shown in chapter III, IV and V. In chapter III, I demonstrate that although mid1 mutants misplace the division septa, the misplaced septa are occluded from cell ends, indicating that an additional negative mechanism inhibits the incorrect positioning of division plane at the cell ends. In chapter IV, I test the current b search, catch, pull and releaseb model for actomyosin ring assembly in certain mutants that are devoid of membrane-associated nodes. I find that cells lacking cortical nodes are able to organize orthogonal actomyosin rings of normal appearance, suggesting that cortical nodes are not essential for the orthogonal ring formation. Finally, in chapter V, I establish a genetic method to reliably and efficiently generate fission yeast cells lacking nuclei and spindle pole bodies.