André Fujita, J. Sato, Kaname Kojima, L. Gomes, Masao Nagasaki, M. Sogayar, S. Miyano
{"title":"Identification of Granger Causality between Gene Sets","authors":"André Fujita, J. Sato, Kaname Kojima, L. Gomes, Masao Nagasaki, M. Sogayar, S. Miyano","doi":"10.1142/S0219720010004860","DOIUrl":"https://doi.org/10.1142/S0219720010004860","url":null,"abstract":"Wiener and Granger have introduced an intuitive concept of causality (Granger causality) between two variables which is based on the idea that an effect never occurs before its cause. Later, Geweke generalized this concept to a multivariate Granger causality, i.e. n variables Granger-cause another variable. Although Granger causality is not \"effective causality\" in the Aristothelic sense, this concept is useful to infer directionality and information flow in observational data. Granger causality is usually identified by using VAR (Vector Autoregressive) models due to their simplicity. In the last few years, several VAR-based models were presented in order to model gene regulatory networks. Here, we generalize the multivariate Granger causality concept in order to identify Granger causalities between sets of gene expressions, i.e. whether a set of n genes Granger-causes another set of m genes, aiming at identifying the flow of information between gene networks (or pathways). The concept of Granger causality for sets of variables is presented. Moreover, a method for its identification with a bootstrap test is proposed. This method is applied in simulated and also in actual biological gene expression data in order to model regulatory networks. This concept may be useful for the understanding of the complete information flow from one network or pathway to the other, mainly in regulatory networks. Linking this concept to graph theory, sink and source can be generalized to node sets. Moreover, hub and centrality for sets of genes can be defined based on total information flow. Another application is in annotation, when the functionality of a set of genes is unknown, but this set is Granger-caused by another set of genes which is well studied. Therefore, this information may be useful to infer or construct some hypothesis about the unknown set of genes.","PeriodicalId":90783,"journal":{"name":"American journal of bioinformatics and computational biology","volume":"40 1","pages":"679-701"},"PeriodicalIF":0.0,"publicationDate":"2010-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84867955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Importance of inhibitors for the Simulation of metabolic Processes: in silico Zn2+ Inhibition of M-Aconitase from Analysis of glycolysis and Krebs Cycle Kinetic Models","authors":"M. Čuperlović-Culf","doi":"10.1142/S0219720010004872","DOIUrl":"https://doi.org/10.1142/S0219720010004872","url":null,"abstract":"Metal ions have a major effect on the metabolic processes in cells either as inhibitors or as integral components of enzymes. The inhibition of enzymes can take place either through the inhibition of gene expression or through inhibition of protein function. A particularly interesting example of the effect of a metal ion on metabolism is the observed inhibition of Krebs cycle and alteration of energy metabolism by zinc (II) cations. In this particular case metal ion inhibition of enzyme is linked to one of the major functions of prostate cells of accumulation and excretion of citrate. Experimental results have shown that increase in concentration of zinc (II) in prostate cells effectively blocks progression of a part of the Krebs cycle leading to change in the concentration of several metabolites with largest effect in the accumulation of citrate. Based on previously reported experimental results, several distinct mechanisms for zinc (II) inhibition of Krebs cycle were proposed. In order to determine the precise mechanism of inhibition in this system, a mathematical model of glycolysis and Krebs cycle was constructed. Three different types of inhibition were analyzed, including competitive and uncompetitive inhibition as well as inhibition through the alteration of the expression level of m-aconitase. The effects of different inhibition models on metabolite concentrations were investigated as a time course simulation of the system of reactions. Several kinetic parameters in the model were optimized in order to best resemble experimental measurements. The simulation shows that only competitive inhibition leads to an agreement with experimental data.","PeriodicalId":90783,"journal":{"name":"American journal of bioinformatics and computational biology","volume":"23 1","pages":"703-715"},"PeriodicalIF":0.0,"publicationDate":"2010-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81212709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Inference of Genetic Networks Using Lpms: Assessment of Confidence Values of Regulations","authors":"Shuhei Kimura, Yuichi Shiraishi, Mariko Okada","doi":"10.1142/S0219720010004859","DOIUrl":"https://doi.org/10.1142/S0219720010004859","url":null,"abstract":"When we apply inference methods based on a set of differential equations into actual genetic network inference problems, we often end up with a large number of false-positive regulations. However, as we must check the inferred regulations through biochemical experiments, fewer false-positive regulations are preferable. In order to reduce the number of regulations checked, this study proposes a new method that assigns confidence values to all of the regulations contained in the target network. For this purpose, we combine a residual bootstrap method with the existing method, i.e. the inference method using linear programming machines (LPMs). Through numerical experiments on an artificial genetic network inference problem, we confirmed that most of the regulations with high confidence values are actually present in the target networks. We then used the proposed method to analyze the bacterial SOS DNA repair system, and succeeded in assigning reasonable confidence values to its regulations. Although this study combined the bootstrap method with the inference method using the LPMs, the proposed bootstrap approach could be combined with any method that has an ability to infer a genetic network from time-series of gene expression levels.","PeriodicalId":90783,"journal":{"name":"American journal of bioinformatics and computational biology","volume":"29 1","pages":"661-677"},"PeriodicalIF":0.0,"publicationDate":"2010-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87481594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Overview of the Algorithmic Session of MCCMB'05","authors":"G. Kucherov, A. Mironov, M. Roytberg","doi":"10.1142/S0219720006002107","DOIUrl":"https://doi.org/10.1142/S0219720006002107","url":null,"abstract":"Genome analysis. This is a most classical bioinformatics topic that includes problems of local and global alignment of genomic sequences and related issues. Grigory Kucherov (LORIA, France) gave a talk on a general method for computing the sensitivity of seeds (small patterns used to spot potential local similarities), and more specifically “subset seeds”, a new concept of seeds. Inna Dubchak (Lawrence Berkeley National Lab, USA) described the VISTA system which is a software system that features several useful programs of genome alignment and analysis.","PeriodicalId":90783,"journal":{"name":"American journal of bioinformatics and computational biology","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2006-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82597392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Kaminuma, N. Heida, T. Yoshizumi, M. Nakazawa, M. Matsui, Tetsuro Toyoda
{"title":"Erratum: \"In Silico Phenotypic Screening Method of Mutants Based on Statistical Modeling of Genetically Mixed Samples\"","authors":"E. Kaminuma, N. Heida, T. Yoshizumi, M. Nakazawa, M. Matsui, Tetsuro Toyoda","doi":"10.1142/S0219720006001783","DOIUrl":"https://doi.org/10.1142/S0219720006001783","url":null,"abstract":"","PeriodicalId":90783,"journal":{"name":"American journal of bioinformatics and computational biology","volume":"85 1","pages":"169"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74039109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modeling and Characterization of Multi-charge Mass Spectra for Peptide Sequencing","authors":"K. F. Chong, K. Ning, H. Leong, P. Pevzner","doi":"10.1142/9781860947292_0014","DOIUrl":"https://doi.org/10.1142/9781860947292_0014","url":null,"abstract":"Sequencing of peptide sequences using tandem mass spectrometry data is an important and challenging problem in proteomics. In this paper, we address the problem of peptide sequencing for multi-charge spectra. Most peptide sequencing algorithms currently handle spectra of charge 1 or 2 and have not been designed to handle higher-charge spectra. We give a characterization of multicharge spectra by generalizing existing models. Using these new models, we have analyzed spectra with charges 1-5 from the GPM [8] datasets. Our analysis shows that higher charge peaks are present and they contribute significantly to prediction of the complete peptide. They also help to explain why existing algorithms do not perform well on multi-charge spectra. We also propose a new de novo algorithm for dealing with multi-charge spectra based on the new models. Experimental results show that it performs well on all spectra, especially so for multi-charge spectra.","PeriodicalId":90783,"journal":{"name":"American journal of bioinformatics and computational biology","volume":"26 1","pages":"1329-1352"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85075941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Erratum: Theoretically Modeling Microarray with the Chemical Equilibrium and Thermodynamics","authors":"Mei Xu","doi":"10.1142/S0219720005001284","DOIUrl":"https://doi.org/10.1142/S0219720005001284","url":null,"abstract":"","PeriodicalId":90783,"journal":{"name":"American journal of bioinformatics and computational biology","volume":"385 1","pages":"771"},"PeriodicalIF":0.0,"publicationDate":"2005-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79341221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}