Temporal and spatial controls of septation in the filamentous fungus Aspergillus nidulans
Abstract
During the cell division cycle DNA must be replicated and segregated to daughter cells with great fidelity. If this genetic material is overreplicated, translocated or lost, daughter cells increase their capacity to acquire improper developmental fates and cancerous properties. The cell division cycle culminates following nuclear division, when cytokinesis partitions the two daughter cells. To ensure that genetic material is properly segregated to daughter cells, cytokinesis is spatially and temporally coordinated with the nuclear division cycle. Aspergillus nidulans, a filamentous fungus amenable to molecular genetics, was employed in an attempt to better understand the physiological and genetic mechanisms of this coordination. Results obtained using a collection of temperature-sensitive nuclear distribution (nudA2, nudC3 and nudF7), nuclear division (nimA5, hfaB3, nimT23cdc25 and nimX2cdc2 ) and septation (sepD5, sepG1 and sepI1) mutants demonstrated that the positioning of nuclei regulates the location of cytokinesis. These mutants were also used to demonstrate that a cell size control, mediated by the universal mitotic regulator p34 nimX/cdc2, temporally coordinates cytokinesis with the nuclear division cycle. Finally, cloning of sepI+ revealed that sepI1 is an allele of bimA+ , a gene which encodes a subunit of the anaphase promoting complex. Characterization of sepI1(bimA10) showed that errors in DNA metabolism block the onset of cytokinesis.
Degree
Ph.D.
Advisors
Hamer, Purdue University.
Subject Area
Genetics|Molecular biology|Microbiology
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