Mitotic Exit Control as an Evolved Complex System (open access)

Mitotic Exit Control as an Evolved Complex System

The exit from mitosis is the last critical decision a cell has to make during a division cycle. A complex regulatory system has evolved to evaluate the success of mitotic events and control this decision. Whereas outstanding genetic work in yeast has led to rapid discovery of a large number of interacting genes involved in the control of mitotic exit, it has also become increasingly difficult to comprehend the logic and mechanistic features embedded in the complex molecular network. Our view is that this difficulty stems in part from the attempt to explain mitotic exit control using concepts from traditional top-down engineering design, and that exciting new results from evolutionary engineering design applied to networks and electronic circuits may lend better insights. We focus on four particularly intriguing features of the mitotic exit control system: the two-stepped release of Cdc14; the self-activating nature of Tem1 GTPase; the spatial sensor associated with the spindle pole body; and the extensive redundancy in the mitotic exit network. We attempt to examine these design features from the perspective of evolutionary design and complex system engineering.
Date: April 25, 2005
Creator: Bosl, W & Li, R
Object Type: Article
System: The UNT Digital Library
59Fe(n,g)60Fe and 60Fe(n,g)61Fe Reaction Rates from Local Systematics (open access)

59Fe(n,g)60Fe and 60Fe(n,g)61Fe Reaction Rates from Local Systematics

We present modeled neutron capture cross sections relevant to stellar production of {sup 60}Fe. Systematics for the input parameters required by the Hauser-Feshbach statistical model are developed based on measured data in the local region of the isotopic plane (20 {le} Z {le} 29, 43 {le} A {le} 65). These parameters and used to calculate reaction cross sections and rates for select target isotopes. Modeled cross sections are compared to experimental data where available. The {sup 59}Fe(n,{gamma}){sup 60}Fe and {sup 60}Fe(n, {gamma}){sup 61}Fe rates are compared to previous calculations. A brief discussion of errors related to the modeling is provided. We conclude by investigating the sensitivity of stellar production of {sup 26}Al and {sup 60}Fe to the {sup 59}Fe(n,{gamma}){sup 60}Fe and {sup 60}Fe(n,{gamma})61Fe reaction rates using a single zone model.
Date: April 25, 2005
Creator: Kelley, K; Hoffman, R D & Drake, M
Object Type: Report
System: The UNT Digital Library
Genomes, Phylogeny, and Evolutionary Systems Biology (open access)

Genomes, Phylogeny, and Evolutionary Systems Biology

With the completion of the human genome and the growing number of diverse genomes being sequenced, a new age of evolutionary research is currently taking shape. The myriad of technological breakthroughs in biology that are leading to the unification of broad scientific fields such as molecular biology, biochemistry, physics, mathematics and computer science are now known as systems biology. Here I present an overview, with an emphasis on eukaryotes, of how the postgenomics era is adopting comparative approaches that go beyond comparisons among model organisms to shape the nascent field of evolutionary systems biology.
Date: March 25, 2005
Creator: Medina, Monica
Object Type: Article
System: The UNT Digital Library