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Full-Text Articles in Life Sciences
Examining Intracellular Phosphorylation Gradients During Cell Division, Lei Tan
Examining Intracellular Phosphorylation Gradients During Cell Division, Lei Tan
Student Theses and Dissertations
The dynamic cellular reorganization needed for successful mitosis requires spatial regulatory cues. I examine this problem at two different levels. First, I analyze a phosphorylation gradient for substrates of the chromosomal passenger complex (CPC) . CPC is a conserved regulator involved in key mitotic events such as chromosome-microtubule attachment and spindle midzone formation. Previously, spatial phosphorylation gradients have been reported for CPC substrates, raising the possibility that CPC-dependent signaling establishes order on the micron-length scale in dividing cells. However, this hypothesis has not been tested, largely because of incomplete characterization of the CPC-dependent phosphorylation dynamics. Here I examine the spatiotemporal …
Characterization Of A Novel Chromatinâ€Induced Mechanism That Couples Microtubule Disassembly And Nuclear Reâ€Formation, Eileen Madeleine Woo
Characterization Of A Novel Chromatinâ€Induced Mechanism That Couples Microtubule Disassembly And Nuclear Reâ€Formation, Eileen Madeleine Woo
Student Theses and Dissertations
Upon completion of mitosis, the disassembly of spindle components and reassembly of nuclear structures occur simultaneously around chromatin. Previous studies have suggested that an important step in this process is the inactivation of the Aurora B kinase by the Triple Aâ€ATPase Cdc48/p97, which physically extracts the protein from chromatin at anaphase. Aurora B is the catalytic subunit of the Chromosome Passenger Complex (CPC), which promotes microtubule polymerization and spindle formation from mitotic chromosomes. Removal of the CPC from chromosomes at anaphase is required for proper nuclear reassembly, but the molecular basis for this requirement remains unclear. On the whole, the …
Peak Mitotic Cyclin Permits Mitotic Exit, Benjamin Drapkin
Peak Mitotic Cyclin Permits Mitotic Exit, Benjamin Drapkin
Student Theses and Dissertations
In eukaryotes, DNA replication, mitosis, and cytokinesis are all regulated by Cyclin-dependent kinase (Cdk). Cyclin/Cdk complexes promote replication origin firing and mitotic entry, and conversely, inhibit pre-replication origin loading and exit from mitosis. Cyclin synthesis and degradation, Cdk phosphorylation and Cdk inhibitors are controlled such that Cdk activity oscillates once per cell cycle. Little is known about the quantitative relationship between the level of Cdk activity and the occurrence, rate, and coordination of cell cycle events. We have addressed this question in Saccharomyces cerevisiae by introducing titrated levels of undegradable mitotic B-cyclin (Clb2kd) in cells prior to release of a …
Using Microscopy To Examine Mechanisms Of Cell Division, Lily Copenagle
Using Microscopy To Examine Mechanisms Of Cell Division, Lily Copenagle
Student Theses and Dissertations
The accurate segregation of chromosomes during cell division requires the assembly of a microtubule-based mitotic spindle. In the research presented here, I examined two aspects of mitotic spindle morphogenesis. First, I looked at how chromosomes attach to microtubules in mitosis. The capture of microtubule plus-ends by kinetochores (the site of chromosome-microtubule attachment) has been described previously. However, recent data suggests that another mechanism must also contribute to this essential process. Here, with the aid of real-time confocal microscopy, I present direct evidence for an additional chromosome-spindle attachment mechanism in which the minus-ends of microtubules attached to chromosomes are captured by …