Department of Biomedical Engineering and Informatics

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Development of User-Centered Interfaces to Search the Knowledge Resources of the Virginia Henderson International Nursing Library
(2003) Jones, Josette; Harris, Marcelline; Thompson, Cheryl Bagley
The primary aim of this collaborative research project was to develop "tell and ask" functional interface where the nurse communicates with the knowledge base by making logical assertions based on his/her domain knowledge.
Searching for Patient Educational Information Using Electronic Resources: An Exploration of Nurses' Search Behavior
(2003) Jones, Josette F.; Brennan, Patricia F.
Nurses are willing to use browser-based electronic resources, such as the WWW to search for patient educational information. But there are problems: Successful searching requires skills unfamiliar to nurses, search results are presented in long undifferentiated lists of available information, and nurses lack the time to sort the search results. The primary aim of this research was to examine the process by which nurses in clinical settings search for patient educational information using browser-based electronic resources.
Conservation of adjacency as evidence of paralogous operons
(2004-09) Janga, Sarath Chandra; Moreno-Hagelsieb, Gabriel
Most of the analyses on the conservation of gene order are limited to orthologous genes. However, the organization of genes into operons might also result in the conservation of gene order of paralogous genes. Thus, we sought computational evidence that conservation of gene order of paralogous genes represents another level of conservation of genes in operons. We found that pairs of genes within experimentally characterized operons of Escherichia coli K12 and Bacillus subtilis tend to have more adjacently conserved paralogs than pairs of genes at transcription unit boundaries. The fraction of same strand gene pairs corresponding to conserved paralogs averages 0.07 with a maximum of 0.22 in Borrelia burgdorferi. The use of evidence from the conservation of adjacency of paralogous genes can improve the prediction of operons in E.coli K12 by ∼0.27 over predictions using conservation of adjacency of orthologous genes alone.
Nebulon: a system for the inference of functional relationships of gene products from the rearrangement of predicted operons
(2005-04) Janga, Sarath Chandra; Collado-Vides, Julio; Moreno-Hagelsieb, Gabriel
Since operons are unstable across Prokaryotes, it has been suggested that perhaps they re-combine in a conservative manner. Thus, genes belonging to a given operon in one genome might re-associate in other genomes revealing functional relationships among gene products. We developed a system to build networks of functional relationships of gene products based on their organization into operons in any available genome. The operon predictions are based on inter-genic distances. Our system can use different kinds of thresholds to accept a functional relationship, either related to the prediction of operons, or to the number of non-redundant genomes that support the associations. We also work by shells, meaning that we decide on the number of linking iterations to allow for the complementation of related gene sets. The method shows high reliability benchmarked against knowledge-bases of functional interactions. We also illustrate the use of Nebulon in finding new members of regulons, and of other functional groups of genes. Operon rearrangements produce thousands of high-quality new interactions per prokaryotic genome, and thousands of confirmations per genome to other predictions, making it another important tool for the inference of functional interactions from genomic context.
MutDB services: interactive structural analysis of mutation data
(Oxford University Press, 2005-07-01) Dantzer, Jessica; Moad, Charles; Heiland, Randy; Mooney, Sean; BioHealth Informatics, School of Informatics and Computing
Non-synonymous single nucleotide polymorphisms (SNPs) and mutations have been associated with human phenotypes and disease. As more and more SNPs are mapped to phenotypes, understanding how these variations affect the function and expression of genes and gene products becomes an important endeavor. We have developed a set of tools to aid in the understanding of how amino acid substitutions affect protein structures. To do this, we have annotated SNPs in dbSNP and amino acid substitutions in Swiss-Prot with protein structural information, if available. We then developed a novel web interface to this data that allows for visualization of the location of these substitutions. We have also developed a web service interface to the dataset and developed interactive plugins for UCSF's Chimera structural modeling tool and PyMOL that integrate our annotations with these sophisticated structural visualization and modeling tools. The web services portal and plugins can be downloaded from http://www.lifescienceweb.org/ and the web interface is at http://www.mutdb.org/ .
The Landscape of the AHRQ Health Information Technology Portfolio
(2006) Dixon, Brian E.
A major agenda item of the President and Congress is widespread adoption of health information technology (health IT) to improve the quality, safety, and efficiency of health care. This has allowed federal agencies to invest additional money into health IT research. The distribution and potential impact of research dollars spent by one agency supporting this agenda is examined here.
The partitioned Rhizobium etli genome: Genetic and metabolic redundancy in seven interacting replicons
(2006-03) González, Víctor; Santamaria, Rosa I.; Bustos, Patricia; Hernández-González, Ismael; Medrano-Soto, Arturo; Moreno-Hagelsieb, Gabriel; Janga, Sarath Chandra; Ramírez, Miguel A.; Jiménez-Jacinto, Verónica; Collado-Vides, Julio; Dávila, Guillermo
We report the complete 6,530,228-bp genome sequence of the symbiotic nitrogen fixing bacterium Rhizobium etli. Six large plasmids comprise one-third of the total genome size. The chromosome encodes most functions necessary for cell growth, whereas few essential genes or complete metabolic pathways are located in plasmids. Chromosomal synteny is disrupted by genes related to insertion sequences, phages, plasmids, and cell-surface components. Plasmids do not show synteny, and their orthologs are mostly shared by accessory replicons of species with multipartite genomes. Some nodulation genes are predicted to be functionally related with chromosomal loci encoding for the external envelope of the bacterium. Several pieces of evidence suggest an exogenous origin for the symbiotic plasmid (p42d) and p42a. Additional putative horizontal gene transfer events might have contributed to expand the adaptive repertoire of R. etli, because they include genes involved in small molecule metabolism, transport, and transcriptional regulation. Twenty-three putative sigma factors, numerous isozymes, and paralogous families attest to the metabolic redundancy and the genomic plasticity necessary to sustain the lifestyle of R. etli in symbiosis and in the soil.
Bacterial regulatory networks are extremely flexible in evolution
(2006-05) Lozada-Chávez, Irma; Janga, Sarath Chandra; Collado-Vides, Julio
Over millions of years the structure and complexity of the transcriptional regulatory network (TRN) in bacteria has changed, reorganized and enabled them to adapt to almost every environmental niche on earth. In order to understand the plasticity of TRNs in bacteria, we studied the conservation of currently known TRNs of the two model organisms Escherichia coli K12 and Bacillus subtilis across complete genomes including Bacteria, Archaea and Eukarya at three different levels: individual components of the TRN, pairs of interactions and regulons. We found that transcription factors (TFs) evolve much faster than the target genes (TGs) across phyla. We show that global regulators are poorly conserved across the phylogenetic spectrum and hence TFs could be the major players responsible for the plasticity and evolvability of the TRNs. We also found that there is only a small fraction of significantly conserved transcriptional regulatory interactions among different phyla of bacteria and that there is no constraint on the elements of the interaction to co-evolve. Finally our results suggest that majority of the regulons in bacteria are rapidly lost implying a high-order flexibility in the TRNs. We hypothesize that during the divergence of bacteria certain essential cellular processes like the synthesis of arginine, biotine and ribose, transport of amino acids and iron, availability of phosphate, replication process and the SOS response are well conserved in evolution. From our comparative analysis, it is possible to infer that transcriptional regulation is more flexible than the genetic component of the organisms and its complexity and structure plays an important role in the phenotypic adaptation.
Identification and analysis of DNA-binding transcription factors in Bacillus subtilis and other Firmicutes- a genomic approach
(2006-06) Moreno-Campuzano, Samadhi; Janga, Sarath Chandra; Pérez-Rueda, Ernesto
Background Bacillus subtilis is one of the best-characterized organisms in Gram-positive bacteria. It represents a paradigm of gene regulation in bacteria due its complex life style (which could involve a transition between stages as diverse as vegetative cell and spore formation). In order to gain insight into the organization and evolution of the B. subtilis regulatory network and to provide an alternative framework for further studies in bacteria, we identified and analyzed its repertoire of DNA-binding transcription factors in terms of their abundance, family distribution and regulated genes. Results A collection of 237 DNA-binding Transcription Factors (TFs) was identified in B. subtilis, half of them with experimental evidence. 59% of them were predicted to be repressors, 17% activators, 17% were putatively identified as dual regulatory proteins and the remaining 6.3% could not be associated with a regulatory role. From this collection 56 TFs were found to be autoregulated, most of them negatively, though a significant proportion of positive feedback circuits were also identified. TFs were clustered into 51 regulatory protein families and then traced on 58 genomes from Firmicutes to detect their presence. From this analysis three families were found conserved in all the Firmicutes; fifteen families were distributed in all Firmicutes except in the phyla Mollicutes; two were constrained to Bacillales and finally two families were found to be specific to B. subtilis, due to their specie specific distribution. Repression seems to be the most common regulatory mechanism in Firmicutes due to the high proportion of repressors in the detected collection in these genomes. In addition, six global regulators were defined in B. subtilis based on the number and function of their regulated genes. Conclusion In this work we identified and described the characteristics associated to the repertoire of DNA-binding TFs in B. subtilis. We also quantified their abundance, family distribution, and regulatory roles in the context of Firmicutes. This work should not only contribute to our understanding of the regulation of gene expression in bacteria from the perspective of B. subtilis but also provide us the basis for comprehensive modeling of transcriptional regulatory networks in Firmicutes.
The distinctive signatures of promoter regions and operon junctions across prokaryotes
(2006-08) Janga, Sarath Chandra; Lamboy, Warren F.; Huerta, Araceli M.; Moreno-Hagelsieb, Gabriel
Here we show that regions upstream of first transcribed genes have oligonucleotide signatures that distinguish them from regions upstream of genes in the middle of operons. Databases of experimentally confirmed transcription units do not exist for most genomes. Thus, to expand the analyses into genomes with no experimentally confirmed data, we used genes conserved adjacent in evolutionarily distant genomes as representatives of genes inside operons. Likewise, we used divergently transcribed genes as representative examples of first transcribed genes. In model organisms, the trinucleotide signatures of regions upstream of these representative genes allow for operon predictions with accuracies close to those obtained with known operon data (0.8). Signature-based operon predictions have more similar phylogenetic profiles and higher proportions of genes in the same pathways than predicted transcription unit boundaries (TUBs). These results confirm that we are separating genes with related functions, as expected for operons, from genes not necessarily related, as expected for genes in different transcription units. We also test the quality of the predictions using microarray data in six genomes and show that the signature-predicted operons tend to have high correlations of expression. Oligonucleotide signatures should expand the number of tools available to identify operons even in poorly characterized genomes.

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