Medicine and Health Sciences Commons^™

Neural Coding And Decoding, Alexander Dimitrov

Systems Science Friday Noon Seminar Series

Methods based on Rate Distortion theory have been successfully used to cluster stimuli and neural responses in order to study neural codes at a level of detail supported by the amount of available data. They approximate the joint stimulus-response distribution by quantizing paired stimulus-response observations into smaller reproductions of the stimulus and response spaces. An optimal quantization is found by maximizing an information-theoretic cost function subject to both equality and inequality constraints, in hundreds to thousands of dimensions. This analytical approach has several advantages over other current approaches:

• it yields the most informative approximation of the encoding scheme given the …

Pcif1 Modulates Pdx1 Protein Stability And Pancreatic Β Cell Function And Survival In Mice, Kathryn C. Claiborn, Mira M. Sachdeva, Corey E. Cannon, David N. Groff, Jeffrey D. Singer, Doris A. Stoffers

Biology Faculty Publications and Presentations

The homeodomain transcription factor pancreatic duodenal homeobox 1 (Pdx1) is a major mediator of insulin transcription and a key regulator of the β cell phenotype. Heterozygous mutations in PDX1 are associated with the development of diabetes in humans. Understanding how Pdx1 expression levels are controlled is therefore of intense interest in the study and treatment of diabetes. Pdx1 C terminus–interacting factor-1 (Pcif1, also known as SPOP) is a nuclear protein that inhibits Pdx1 transactivation. Here, we show that Pcif1 targets Pdx1 for ubiquitination and proteasomal degradation. Silencing of Pcif1 increased Pdx1 protein levels in cultured mouse β cells, and Pcif1 …

Metagenomes From High-Temperature Chemotrophic Systems Reveal Geochemical Controls On Microbial Community Structure And Function, William P. Inskeep, Douglas B. Rusch, Zackary J. Jay, Markus J. Herrgard, Mark A. Kozubal, Toby H. Richardson, Richard E. Macur, Natsuko Hamamura, Ryan Dem. Jennings, Bruce W. Fouke, Anna-Louise Reysenbach, Frank Roberto, Mark Young, Ariel Schwartz, Eric S. Boyd, Jonathan H. Badger, Eric J. Mathur, Alice C. Ortmann, Mary Bateson, Gill Geesey

Biology Faculty Publications and Presentations

The Yellowstone caldera contains the most numerous and diverse geothermal systems on Earth, yielding an extensive array of unique high-temperature environments that host a variety of deeply-rooted and understudied Archaea, Bacteria and Eukarya. The combination of extreme temperature and chemical conditions encountered in geothermal environments often results in considerably less microbial diversity than other terrestrial habitats and offers a tremendous opportunity for studying the structure and function of indigenous microbial communities and for establishing linkages between putative metabolisms and element cycling. Metagenome sequence (14-15,000 Sanger reads per site) was obtained for five hightemperature (>65°C) chemotrophic microbial communities sampled from …

Reconstructability Analysis As A Tool For Identifying Gene-Gene Interactions In Studies Of Human Diseases, Stephen Shervais, Patricia L. Kramer, Shawn K. Westaway, Nancy J. Cox, Martin Zwick

Systems Science Faculty Publications and Presentations

There are a number of common human diseases for which the genetic component may include an epistatic interaction of multiple genes. Detecting these interactions with standard statistical tools is difficult because there may be an interaction effect, but minimal or no main effect. Reconstructability analysis (RA) uses Shannon’s information theory to detect relationships between variables in categorical datasets. We applied RA to simulated data for five different models of gene-gene interaction, and find that even with heritability levels as low as 0.008, and with the inclusion of 50 non-associated genes in the dataset, we can identify the interacting gene pairs …

The Isolation Of Viruses Infecting Archaea, Kenneth M. Stedman, Kate Porter, Mike L. Dyall-Smith

Biology Faculty Publications and Presentations

A mere 50 viruses of Archaea have been reported to date; these have been investigated mostly by adapting methods used to isolate bacteriophages to the unique growth conditions of their archaeal hosts. The most numerous are viruses of thermophilic Archaea. These viruses have been discovered by screening enrichment cultures and novel isolates from environmental samples for their ability to form halos of growth inhibition, or by using electron microscopy to screen enrichment cultures for virus-like particles. Direct isolation without enrichment has not yet been successful for viruses of extreme thermophiles. On the other hand, most viruses of extreme halophiles, the …