A Time Series Analysis of Microarray Data

  • Authors:
  • Affiliations:
  • Venue:
  • BIBE '04 Proceedings of the 4th IEEE Symposium on Bioinformatics and Bioengineering
  • Year:
  • 2004

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Abstract

As the capture and analysis of single-time-point microarrayexpression data becomes routine, investigators are turningto time-series expression data to investigate complexgene regulation schemes and metabolic pathways. These investigationsare facilitated by algorithms that can extractand cluster related behaviors from the full population oftime-series behaviors observed. Although traditional clusteringtechniques have shown to be effective for certaintypes of expression analysis, they do not take the biologicalnature of the process into account, and therefore are clearlynot optimized for this purpose. Moreover, the current approachesprovide internal comparisons for the experimentsutilized for clustering, but cross-comparisons between clusteredresults are qualitative and subjective. We present acombination of current and novel methods for the analysisof time series gene expression data. We focus on an actualstudy we have performed for Haemophilus influenzaewhich is a major cause of otitis media in children. We firstperform a discretization of the gene expression data thattakes both positive and negative correlations into considerationand then develop a clustering algorithm optimizedfor such data that allows elucidation and searching of time-seriespatterns. The resulting approach allows time-seriesdata to be usefully compared across multiple experiments.We demonstrate the success of our algorithm by showingsome of the genes that it finds to be co-regulated are not detectedby current methods. As a result we are able to identifyseveral signal pathways that initiate competence development,and to characterize the transcriptomes of wild-typeand an adenylate cyclase mutant (cya) strains under bothnutrient-limiting and nutrient-complete growth conditions.