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Bioinformatics:
Building Bridges

Posters


1
Using Microarray Gene Expression Profiling to Characterize Lung Allograft Rejection

Jeff Lande*, Vince Gimino^, Marshall Hertz^, Richard King*

*Molecular, Cellular, Developmental Biology and Genetics, and ^Pulmonary Medicine

Acute rejection is common after lung transplantation, occurring in up to 50% of recipients during the first post-transplant year. Although it is almost never immediately life threatening, acute rejection is a major risk factor for the later development of chronic lung rejection, or obliterative bronchiolitis, the most important threat to the long-term survival of lung transplant recipients. The statistical relationship between acute and chronic rejection exists despite the fact that, in most cases, the histologic findings of acute rejection resolve after treatment. Based on this observation, a fundamental assumption of the proposed research is that specific genes are activated during acute rejection, some of which remain persistently activated despite treatment, and contribute to the pathogenesis of obliterative bronchiolitis; Identification of these genes can serve to identify recipients at-risk for chronic rejection. Our overall goal is to use large-scale gene expression microarray (>10,000 genes) technology to identify patterns of known and novel gene expression that reliably and reproducibly identify lung transplant recipients with acute rejection who are at-risk for chronic rejection.


2
Graduate Training in Bioinformatics at the University of Minnesota

Lynda B.M. Ellis

Laboratory Medicine and Pathology

Bioinformatics is an interdisciplinary research area that applies computer and information science to solve biological problems. On February 8, 2002, the Graduate Program in Bioinformatics (http://www.binf.umn.edu/) was approved by the University of Minnesota Regents. This program now offers a minor in bioinformatics to students enrolled in a UM graduate program. We will describe the present status of and future plans for the graduate program.


3
Global analysis of mRNA decay in T cells

Arvind Raghavan*, Cavan S. Reilly^, Rachel L. Robison*, Michelle S. Abelson*, Mitchell Krathwohl~ and Paul R. Bohjanen*#

*Microbiology, ^Biostatistics, ~Medicine, and #Center for Immunology

Regulation of gene expression at the level of mRNA decay facilitates rapid, selective and temporally precise responses to T cell activation. We have used oligonucleotide microarrays to profile the decay rates of mRNA transcripts in resting and stimulated T cells. Data from four independent experiments was analyzed using a first order decay model and RNA half-lives (with 95% confidence intervals) were determined for each of approximately 6000 expressed transcripts. While the majority of transcripts in resting T cells were stable, our data identified numerous short-lived transcripts encoding important regulatory genes including transcription factors, signal transduction regulators, cell cycle regulators, and regulators of apoptosis. In addition, we found that T cell activation led to dramatic and statistically significant changes in the decay rates of numerous transcripts; in some cases the mRNA was stabilized and in others it was destabilized. The technology employed in this study allowed the identification of numerous genes that are regulated at the level of mRNA stability. Our data demonstrate that the rate of mRNA decay of numerous important regulatory genes changes in a stimulus-dependent manner, highlighting the importance of mRNA stability in the regulation of gene expression.


4
Superfamily Expansion: Where Does It End?

Jennifer L. Seffernick, Larry P. Wackett, and Patsy C. Babbitt

Biochemistry, Molecular Biology and Biophysics

Superfamilies are composed of distantly related proteins that share functional or structural connections to a common ancestor. Low sequence identity causes difficulties in identifying additional superfamily members. In this study, a combination of PSI-BLAST and SHOTGUN, a program that correlates the output from thousands of individual PSI-BLAST analyses, was used to expand the amidohydrolase superfamily, with a low false positive rate. The amidohydrolase superfamily contains diverse hydrolytic enzymes that utilize divalent metals to activate water for nucleophilic attack on the substrate. High conservation of three dimensional structure and catalytic mechanism across this superfamily has been observed in members where crystal structures are available, such as urease, adenosine deaminase, and phosphotriesterase. Among the reactions catalyzed by superfamily members are deamination, deamidation, dehalogenation, and dephophorylation. Further characterization of this superfamily in sequence space could provide insights into how evolution expands enzymatic functionality without altering or having to engineer new protein scaffoldings.


5
Bioinformatics and the Supercomputing Institute

Zheng Jin Tu, Yuk Sham, and Patton L. Fast

Supercomputing Institute

The Supercomputing Institute (www.msi.umn.edu) was created in 1984 to provide state-of-the-art high-performance computing resources to the University of Minnesota research community. The Institute has built a strong tradition of providing researchers with not only leading edge hardware and software, but also providing technical user support in the form of tutorials, workshops, and one-on-one assistance. Current technical user support staffs have expertise in bioinformatics, molecular modeling and drug design, computational chemistry, scientific visualization, computational fluid dynamics, structure mechanics, and geophysics.

The Supercomputing Institute is committed to providing the computational resources (hardware, software, technical assitance, etc.) that are required to keep the University of Minnesota computational biology research community on the leading edge of academic research. Please stop by and talk with us at our poster to discover how the Institute can help make your research more efficient. Contact us by phone, 612-626-0802, or by email, help@msi.umn.edu if you have questions before or after the symposium.


6
Comparison of Cluster Analyses by Using the Maximum Kappa Statistic

Changchun Wang*^, Mark Rutherford*, and Cavan Reilly^

*Veterinary Pathobiology, ^Biostatistics

Cluster analysis has been used to find the pattern of gene expression extensively. In practice, different clustering analyses usually result in different inference for the same predefined number of clusters. This brings up the question of practical importance: how to compare the results of different cluster analyses? It is the problem of how to measure the agreement among different 'raters'. In order to answer this question, we proposed the maximum kappa statistic to compare cluster analysis for gene analysis. Three algorithms of cluster more than six, we implement the Metropolis Algorithm to find the maximum kappa statistic quickly and accurately. Application shows that the maximum kappa statistic is very stable statistic to describe the relative agreement on different cluster analysis, no matter what the predefined number of cluster it is.


7
Using Data Mining to Unravel the Puzzle of Life

Mukund Deshpande, Michihiro Kuramochi, Ying Zhao, and George Karypis

Computer Science & Engineering

In this poster we present our research in developing data mining techniques for analyzing genomic and proteomic datasets. In particular, we present our research in the following three different areas: (i) Development of accurate and scalable algorithms for clustering high data sets arising in many biological applications including gene expressions and protein sequences, and present CLUTO, a general purpose clustering software tool for clustering such datasets. (ii) Development of gene-expression based functional annotation algorithms that were shown to produce promising results for correctly annotating genes when their expression was monitored under a wide range of conditions. (iii) Development of novel sequence-based classification algorithms that are inherently more advanced than techniques based on Markov models as they are able to efficiently learn non-linear discriminatory models.


8
Seeking the Danio rerio Secretome

Eric Klee, Fei Xu, Steve Ekker, and Lynda Ellis

Beckman Center for Transposon Research

The goal of this work is to define a process which will use the information in publicly availble databases to assist laboratory investigators in their protein function research. Limitations caused by the lack of a fully sequenced Danio rerio (zebrafish) genome prevent the use of standard predictive software tools in identifying the target secreted proteins. Using genetic homology among eukaryotes, alignment screenings, and predictive assessments of sequence fragments, this problem is overcome and 496 highly probable secreted protein sequences are identified.


9
The Relative Importance of Segmental and Tandem Duplications in Gene Family Evolution in Arabidopsis thaliana

Steven B. Cannon*, Andrew Baumgarten*, Georgiana May*^, and Nevin D. Young*~

*Plant Biology, ^Ecology, Evolution and Behavior, ~Plant Pathology

The complete sequencing of the Arabidopsis thaliana genome has revealed numerous large-scale segmental duplications. These duplications have probably occurred several times, and can be placed into duplication age classes relative to one another (Vision et al., 2000). These segmental duplication blocks can be used to provide internal relative reference points in gene family phylogenies. At the same time, tandem or local duplications (closely related genes within 250 kb of one another) are also common. What are the relative frequencies of segmental and local duplications in the evolution of large gene families? We have developed software to identify clades in gene family phylogenies that have arisen either by segmental or local duplication. In Arabidopsis thaliana, we find that contributions made by these two mechanisms differ greatly from gene family to gene family. We describe the possible biological significance of these evolutionary differences for several gene families.


10
Speedup at what cost? Comparing heuristic and complete homology search algorithms

Christopher Dwan and Ernest Retzel

Center for Computational Genomics and Bioinformatics

Sequence based homology search is the workhorse of bioinformatic analysis. The algorithmic mechanics underlying homology search tools are poorly understood by the major part of the user community. Comparative studies are rare, ad-hoc, and usually performed as part of the testing of a proposed new algorithm. Such new algorithms would never be written except in response to perceived flaws in existing tools, so the authors are hard pressed to maintain impartiality. We present several sets of test data representing divergent real-world use cases for sequence based homology search algorithms. We define several metrics for comparison, and present visualizations of these metrics which allow quick, clear communication of the results. Example results are presented for several homology search tools.


11
Microbial Metabolism: Document, Predict, Discover

Bo Kyeng Hou, Wenjun Kang, Larry P. Wackett, Lynda B.M. Ellis

Center for Environmental Molecular Science

The breadth of microbial metabolism has been surveyed by the authors and represented on the University of Minnesota Biocatalysis/Biodegradation Database (UM-BBD): http://umbbd.ahc.umn.edu/. The database depicts metabolism of 50 chemical functional groups. At least twice that number might be metabolized by microbes. Thus, half of the unique biochemical reactions catalyzed by microbes could remain to be discovered. Our present work can be summarized as: document, predict, discover. We continue to document known microbial catabolism in the UM-BBD. Computational methods are being developed to use UM-BBD data to predict microbial metabolism that is not yet discovered. And a concentrated effort is being made to discover new microbial metabolism. In this way, we expect to greatly expand the range of known metabolism and document that on the UM-BBD to enhance global efforts on microbial functional genomics.


Symp HomeBInf Home Page Author(s): Jeff Lande, Lynda Ellis