: Simon M. Lin, Kimberly F. Johnson (Eds.)
: Methods of Microarray Data Analysis II
: Kluwer Academic Publishers
: 9780306475986
: 1
: CHF 96.80
:
: Naturwissenschaft
: English
: 214
: DRM
: PC/MAC/eReader/Tablet
: PDF
Microarray technology is a major experimental tool for functional genomic explorations, and will continue to be a major tool throughout this decade and beyond. The recent explosion of this technology threatens to overwhelm the scientific community with massive quantities of data. Because microarray data analysis is an emerging field, very few analytical models currently exist. Methods of Microarray Data Analysis II is the second book in this pioneering series dedicated to this exciting new field. In a single reference, readers can learn about the most up-to-date methods, ranging from data normalization, feature selection, and discriminative analysis to machine learning techniques.

Currently, there are no standard procedures for the design and analysis of microarray experiments. Methods of Microarray Data Analysis II focuses on a single data set, using a different method of analysis in each chapter. Real examples expose the strengths and weaknesses of each method for a given situation, aimed at helping readers choose appropriate protocols and utilize them for their own data set. In addition, web links are provided to the programs and tools discussed in several chapters. This book is an excellent reference not only for academic and industrial researchers, but also for core bioinformatics/genomics courses in undergraduate and graduate programs.

Writ en for: Academic and industrial researchers
5 EXTRACTING GLOBAL STRUCTURE FROM GENE EXPRESSION PROFILES (p. 81-82)

Charless Fowlkes1, Qun Shan2, Serge Belongie3, and Jitendra Malik1
Departments of Computer Science1 and Molecular Cell Biology 2, University of California at
Berkeley, Department of Computer Science and Engineering, University of California at San Diego3


Abstract: We have developed a program, GENECUT, for analyzing datasets from gene expression profiling. GENECUT is based on a pairwise clustering method known as Normalized Cut (Shi and Malik, 1997). GENECUT extracts global structures by progressively partitioning datasets into well-balanced groups, performing an intuitive k-way partitioning at each stage in contrast to commonly used 2-way partitioning schemes. By making use of the Nyström approximation, it is possible to perform clustering on very large genomic datasets.

Key words: gene expression profiles, clustering analysis, spectral partitioning

1. INTRODUCTION

DNA microarray technology empowers biologists to analyze thousands of mRNA transcripts in parallel, providing insights about the cellular states of tumor cells, the effect of mutations and knockouts, progression of the cell cycle, and reaction to environmental stresses or drug treatments. Gene expression profiles also provide the necessary raw data to interrogate cellular transcription regulation networks. Efforts have been made in identifying cis acting elements based on the assumption that co-regulated genes have a higher probability of sharing transcription factor binding sites. There is a well-recognized need for tools that allow biologists to explore public domain microarray datasets and integrate insights gained into their own research. One important approach for structuring the exploration of gene expression data is to find coherent clusters of both genes and experimental conditions. The association of unknown genes with functionally well-characterized genes will guide the formation of hypotheses and suggest experiments to uncover the function of these unknown genes. Similarly, experimental conditions that cluster together may affect the same regulatory pathway.

Unsupervised clustering is a classical data analysis problem that is still an active area of intensive research in the computer science and statistics communities (Ripley, 1996). Broadly speaking, the goal of clustering is to partition a set of feature vectors into k groups such that the partition is"good" according to some cost function. In the case of genes, the feature vector is usually the degree of induction or suppression over some set of experimental conditions. As of yet, there is no clear consensus as to which algorithms are most suitable for gene expression data.

Clustering methods generally fall into one of two categories: central or pairwise (Buhmann, 1995). Central clustering is based on the idea of prototypes, wherein one finds a small number of prototypical feature vectors to serve as"cluster centers". Feature vectors are then assigned to the most similar cluster center. Pairwise methods are based directly on the distances between all pairs of feature vectors in the data set. Pairwise methods don’t require one to solve for prototypes, which provides certain advantages over central methods. For example, when the shape of the clusters are not simple, compact clouds in feature space, central methods are ill-suited while pairwise methods perform well since similarity is allowed to propagate in a transitive fashion from neighbor to neighbor. A family of genes related by a series of small mutations might well exhibit this sort of structure, particularly when features are based on sequence data. Clustering algorithms can also often be characterized as greedy or global in nature. The agglomerative clustering method used by Eisen et al. (1998) to order microarray data is an example of a greedy pairwise method: it starts with a full matrix of pairwise distances, locates the smallest value, merges the corresponding pair, and repeats until the whole dataset has been merged into a single cluster. Because this type of process only considers the closest pair of data points at each step, global structure present in the data may not be handled properly.
Contents5
Contributors7
Acknowledgements9
Preface10
INTRODUCTION11
CAMDA 2001 Data Sets12
Feature Selection and Extraction12
Clustering Strategies13
Modeling Complex Systems14
Ontologies, Semantic Understanding, and Functional Genomics15
A standard protocol?16
Web Companion17
1 AN INTRODUCTION TO DNA MICROARRAYS18
1. INTRODUCTION TO FUNCTIONAL GENOMICS18
2. MICROARRAY TECHNOLOGY19
3. MICROARRAY DATA22
4. MICROARRAY EXPERIMENT GOALS23
5. MICROARRAY EXPERIMENTAL DESIGN25
6. MICROARRAY DATA ANALYSIS26
7. RESULT VALIDATION27
7.1 Sample and Data Triage27
7.2 Statistical Validation27
7.3 Biological Validation28
8. CONCLUSION28
REFERENCES29
2 EXPERIMENTAL DESIGN FOR GENE MICROARRAY EXPERIMENTS AND DIFFERENTIAL EXPRESSION ANALYSIS31
1. INTRODUCTION31
2. DESIGN OF MICROARRAY EXPERIMENTS32
2.1 Biological variation33
2.2 Technological variations34
2.3 Microarray quality checklist36
3. EXPERIMENTAL DESIGNS THAT INCORPORATE BIOLOGICAL AND TECHNOLOGICAL VARIATION37
3.1 Block designs37
3.2 Randomization38
3.3 Loop designs38
3.4 Split plot designs39
3.5 Optimal designs40
4. DESIGN OF MICROARRAYS41
5. NORMALIZATION MODELS42
5.1 Data transformation and background removal42
5.2 Linear vs. non-linear effects43
5.3 Random vs. fixed effects43
5.4 Ordinary least squares vs. orthogonal regression43
5.5 Means vs. medians43
5.6 Self-consistency44
5.7 Flagging outliers44
6. DIFFERENTIAL EXPRESSION44
6.1 Error models45
6.2 Bayesian approach45
6.3 Adjustment for multiple comparisons and power considerations46
7. FINAL REMARKS46
ACKNOWLEDGEMENTS47
REFERENCES47
3 MICROARRAY DATA PROCESSING AND ANALYSIS50
1. INTRODUCTION50
2. DESIGN OF THE ARRAY51
3. DATA ACQUISITION AND IMAGE ANALYSIS53
4. NORMALISATION AND FILTERING54
5. DATA STORAGE55
6. ADDRESSING BIOLOGICAL QUESTIONS57
7. DATA ANALYSIS58
7.1 Two conditions comparison58
7.2 Multiple conditions comparison.58
7.3 Gene networks64
8. CONCLUSIONS AND FUTURE PROSPECTS65
REFERENCES66
4 BIOLOGY-DRIVEN CLUSTERING OF MICROARRAY DATA71
1. INTRODUCTION71
2. THE ANNOTATION PROBLEM72
2.1 Reannotating the Spots72
2.2 Finding Functional Categories73
3. PRELIMINARY ANALYSIS76
3.1 Data Preprocessing76
3.2 Updating Cell Line Classifications78
3.3 Choosing a Distance Metric79
4. CHROMOSOMAL CLUSTERING80
5. FUNCTIONAL CLUSTERING82
6. CONCLUSIONS83
ACKNOWLEDGEMENTS85
REFERENCES85
5 EXTRACTING GLOBAL STRUCTURE FROM GENE EXPRESSION PROFILES86
1. INTRODUCTION86
2. CLUSTERING WITH NORMALIZED CUT88
2.1 The NCut Criterion88
2.2 K-Way Partitioning89
2.3 Clustering Large Datasets90
3. RESULTS90
4. CONCLUSIONS94
REFERENCES94
6 SUPERVISED NEURAL NETWORKS FOR CLUSTERING CONDITIONS IN DNA ARRAY DATA AFTER REDUCING NOISE BY CLUSTERING GENE EXPRESSION PROFILES96
1. INTRODUCTION96
2. COMPARATIVE PERFORMANCES OF CLUSTERING METHODS98
2.1 Data set used98
2.2 Comparative runtimes98
2.3 Comparative accuracy100
2.4 Conclusions on comparative performances101
3. CLUSTERING OF CONDITIONS102
3.1 The problem of noisy patterns102
3.2 Clustering of conditions and noise reduction103
4. CONCLUSIONS107
ACKNOWLEDGEMENTS107
REFERENCES107
7 BAYESIAN DECOMPOSITION ANALYSIS OF GENE EXPRESSION IN YEAST DELETION MUTANTS109
1. INTRODUCTION110
1.1 The Development of Cancer110
1.2 Microarray Measurements and Analysis110
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