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Zhong Gao

Bioinformatics & Computational Biology Student Seminar Series

Genome-wide Search for Novel Tumor Necrosis Factor (TNF)Proteins in Human and Arabidopsis genomes

Zhong Gao
Major professors: Dr. Vasant Honavar and Dr. Kai-Ming Ho
Iowa State University
Friday, March 8, 2002
1:10 p.m.
1420 Molecular Biology Building

Abstract
Tumor necrosis factors (TNF) and TNF receptors (TNFR) are directly involved in human signaling pathways for cell proliferation, survival, and differentiation. A TNFR-like protein (Crinkly4, CR4) has been identified to be involved in signal transduction and cell fate decisions in maize endosperm development(Becraft et al.,1996, Science 273:1406). However, so far no corresponding TNF-like ligand has been identified in plants. We have used genome-wide secondary structure prediction and protein structure threading to search novel TNF candidates in human genome and possible TNF-like signal proteins in Arabidopsis. Gapped protein structure threading, based on a residue interaction model and energy minimization, can recognize native-like protein structures. Several candidates have been screened out and 3D structure models of these candidates have been constructed. Surface properties of known TNFs and the candidates are being further studied. The research demonstrates the significance of protein structure threading in genome-wide functional analysis.


Fang Fang

Bioinformatics & Computational Biology Student Seminar Series

Test of a Bayesian recombination detection method

Fang Fang
B.S.: Harbin Medical University, P. R. China
Major Professor: Karin Dorman
Iowa State University
Friday, March 8, 2002
1:10 p.m.
1420 Molecular Biology Building

Abstract
Recombination explains a considerable amount of genetic diversity in natural populations. In general genes located in genomic regions with low levels of recombination have relatively lower levels of polymorphism. Recombination especially affects DNA/RNA virus diversity, pathogenesis, and ability to evade immune pressures and antiviral agents. Thus the accurate detection of recombinant from DNA/RNA virus sequences is very important. Two basic methods ñ distance method and phylogenetic method are available now to detect recombination and look for breakpoints in highly variable sequences, and different approaches have been developed. Most approaches fall into a sequential testing trap, by first using the data to determine recombinant structure and then using the same data to assess significance conditional on the optimal solution. For overcoming this shortfall a new model is developed by using extended Bayesian multiple change-point model to infer the existence and locations cross-over point and parental subtypes. Bayes factor was introduced to test significance of recombination events. This new model has been used to test recombination in any other viruses except HIV. Here we used HBV recombination to test the Bayesian multiple change-point model.


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