69,924 research outputs found
Network rewiring is an important mechanism of gene essentiality change.
Gene essentiality changes are crucial for organismal evolution. However, it is unclear how essentiality of orthologs varies across species. We investigated the underlying mechanism of gene essentiality changes between yeast and mouse based on the framework of network evolution and comparative genomic analysis. We found that yeast nonessential genes become essential in mouse when their network connections rapidly increase through engagement in protein complexes. The increased interactions allowed the previously nonessential genes to become members of vital pathways. By accounting for changes in gene essentiality, we firmly reestablished the centrality-lethality rule, which proposed the relationship of essential genes and network hubs. Furthermore, we discovered that the number of connections associated with essential and non-essential genes depends on whether they were essential in ancestral species. Our study describes for the first time how network evolution occurs to change gene essentiality
Metazoans evolved by taking domains from soluble proteins to expand intercellular communication network.
A central question in animal evolution is how multicellular animals evolved from unicellular ancestors. We hypothesize that membrane proteins must be key players in the development of multicellularity because they are well positioned to form the cell-cell contacts and to provide the intercellular communication required for the creation of complex organisms. Here we find that a major mechanism for the necessary increase in membrane protein complexity in the transition from non-metazoan to metazoan life was the new incorporation of domains from soluble proteins. The membrane proteins that have incorporated soluble domains in metazoans are enriched in many of the functions unique to multicellular organisms such as cell-cell adhesion, signaling, immune defense and developmental processes. They also show enhanced protein-protein interaction (PPI) network complexity and centrality, suggesting an important role in the cellular diversification found in complex organisms. Our results expose an evolutionary mechanism that contributed to the development of higher life forms
Climate change impacts on hydrology and water resources of the Upper Blue Nile River Basin, Ethiopia
Climate change / Hydrology / River basins / Runoff / Precipitation / Models / Dams / Operating policies / Water power / Drought / Analysis / Africa / Ethiopia / Egypt / Sudan / Upper Blue Nile River Basin
Potential contributions of noncontact atomic force microscopy for the future Casimir force measurements
Surface electric noise, i.e., the non-uniform distribution of charges and
potentials on a surface, poses a great experimental challenge in modern
precision force measurements. Such a challenge is encountered in a number of
different experimental circumstances. The scientists employing atomic force
microscopy (AFM) have long focused their efforts to understand the
surface-related noise issues via variants of AFM techniques, such as Kelvin
probe force microscopy or electric force microscopy. Recently, the physicists
investigating quantum vacuum fluctuation phenomena between two closely-spaced
objects have also begun to collect experimental evidence indicating a presence
of surface effects neglected in their previous analyses. It now appears that
the two seemingly disparate science communities are encountering effects rooted
in the same surface phenomena. In this report, we suggest specific experimental
tasks to be performed in the near future that are crucial not only for
fostering needed collaborations between the two communities, but also for
providing valuable data on the surface effects in order to draw the most
realistic conclusion about the actual contribution of the Casimir force (or van
der Waals force) between a pair of real materials.Comment: The paper appeared in the Proceedings to the 12th International
Conference on Noncontact Atomic Force Microscopy (NC-AFM 2009) and Casimir
2009 Satellite Worksho
Implementation of Particle Flow Algorithm and Muon Identification
We present the implementation of the Particle Flow Algorithm and the result
of the muon identification developed at the University of Iowa. We use Monte
Carlo samples generated for the benchmark LOI process with the Silicon Detector
design at the International Linear Collider. With the muon identification, an
improved jet energy resolution, good muon efficiency and purity are achieved.Comment: 4 pages, 2 figures, lcws08 at Chicag
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